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Risk of Plasmodium vivax malaria reintroduction in Uzbekistan: Genetic characterization of parasites and status of potential malaria vectors in the Surkhandarya region
Abstract
Plasmodium vivax malaria was eradicated from Uzbekistan in 1961. Due to resurgence of the disease in neighbouring states and massive population
migration, there has been an increase of P. vivax malaria, imported from Tajikistan, resulting in a number of indigenous cases being identified in areas bordering that country.
A molecular study using the merozoite surface protein 1 (msp-1) gene as a marker was performed on 24 P. vivax genomic isolates from 12 indigenous and 10 imported malaria cases that occurred in the Surkhandarya region during the summer
of 2002. Results have shown a significant difference in the frequency of msp-1 types between indigenous and imported isolates, the latter showing greater genetic heterogeneity. An entomological investigation
in the area suggested that three Anopheles species, namely A. superpictus, A. pulcherrimus and A. hyrcanus may have a potential role in the endemic transmission of P. vivax.
... In P. vivax, two types of repeat elements are found, VK210 and VK247 (Rosenberg et al., 1989), and a given csp gene exclusively bears either the VK210 type (type I repeats based on GDRADGQPA) or the VK247 type (type II repeats based on ANGAGNQPG). Both csp gene types were detected in Uzbekistan (Severini et al., 2004), Afghanistan (Zakeri et al., 2010a), Iran and Pakistan (Zakeri et al., 2010b). ...
... In Central Asia, such a reduced variability is detected for the first time. Early on, the reduced diversity was detected in Uzbekistan among genomic isolates homologous to the Belem type from indigenous cases detected in the Surkhandarya region, including all the indigenous cases registered in Uzbekistan in 2002 (Severini et al., 2004). Unfortunately, a detailed comparison of P. vivax parasites from Kyrgyz Republic and Uzbekistan is not possible since GenBank does not contain data on the DNA structure of msp-1 and dbp II in Uzbek P. vivax. ...
... This greater genetic diversity may contribute to better adaptation to different environments and vectors. Differences in the genetic diversity, as well as in the genetic structure, of parasite populations have already been noted in other tertian malaria foci in the regions of Central and West Asia (Severini et al., 2004;Zakeri et al., 2006Zakeri et al., , 2010aZakeri et al., , 2010b. A high P. vivax genetic diversity is observed in endemic regions with intensive population migrations (Severini et al., 2004;Zakeri et al., 2006). ...
At the end of 2016, Kyrgyz Republic was certified by the World Health Organization as a malaria-free country, while only a decade ago this disease posed a serious health threat. The progress achieved by Kyrgyz Republic provides a unique example of tertian (Plasmodium vivax) malaria elimination. This success was based on an integrated approach, including measures for the treatment of infected people and disease prevention, vector control and the development of an effective national epidemiological surveillance system. Lower P. vivax msp-1, msp-3α csp and dbpII genes polymorphism was revealed in Kyrgyz Republic in compare with that in Tajikistan. Molecular characterization of the causative agent found that P. vivax populations in Kyrgyz Republic was comprised by several lineages, highly divergent in the south-western and genetically homogeneous in the northern regions of Kyrgyz Republic, d. Such profile in the northern regions was compatible with several recent introductions rather than a long-term endemic circulation of the parasite. A low level of genetic variability suggested that the parasitic systems of tertian malaria, were not adapted, which, along with other factors, largely determined the possibility of malaria elimination in northern Kyrgyz Republic. Other determinants included environmental, social, and epidemiological factors that limited the spread of malaria. South-western Kyrgyz Republic, a region with a high level of interstate migration, requires considerable attention to prevent the spread of malaria.
... Thus, knowing the evolutionary history of malarial parasite populations is essential for detecting genetic adaptive variation such as that expected in potential antigens and for understanding patterns of linkage disequilibrium that could enable the identification of genes associated with, for example, drug resistance. Understanding the geographic population structure is also important in epidemiological surveillance studies because the source of parasites could be established more easily in cases of imported malaria [14][15][16]. ...
... We suggest that an extensive and spatially defined sampling, together with additional independent markers [26], is needed to understand the history of this malarial parasite of humans better. Such investigations will improve the understanding of P. vivax genetic variation, enabling the identification of adaptive variation, the interpretation of linkage patterns, leading to the identification of genes potentially involved in drug resistance, and the development of molecular surveillance protocols to identify the source of parasites involved in outbreaks in areas in which malaria is imported [7,[14][15][16]. ...
The evolutionary history of Plasmodium vivax has recently been addressed in terms of its origin as a parasite of humans and the age of extant populations. The consensus is that P. vivax originated as a result of a host switch from a non-human primate to hominids and that the extant populations did not originate as recently as previously proposed. Here, we show that, in a comparison of parasite isolates from across the world, Asian populations of P. vivax are the oldest. We discuss how this result, together with the phylogenetic evidence that P. vivax derived from Plasmodium found in Southeast Asian macaques, is most simply explained by assuming an Asian origin of this parasite. Nevertheless, the available data show only the tip of the iceberg. We discuss how sampling might affect time estimates to the most recent common ancestor for P. vivax populations and suggest that spatially explicit estimates are needed to understand the demographic history of this parasite better.
... The discussion about climate change and large population movements has provoked interest in the question whether malaria could become re-established in Europe under changing environmental and demographic circumstances. This suggestion is fuelled by the recent spread of malaria in Central Asian Republics following the collapse of the USSR and by persistent malarial infections in South Korea along the boundary with North Korea (Feighner et al. 1998, Sabatinelli 2000, Severini et al. 2004, Yeom et al. 2005. Here, conditions of local transmission are not unlike those experienced in many parts of Europe, although the anopheline species responsible for the transmission are different. ...
... the infected RBCs, sequestration and removal of RBCs by Similarly, Uzbekistan was also faced the same situation the spleen. In addition, release of cytokines may also be where malaria was eliminated; however reappearance of considered as the contributing factor for lowering the the disease result due to the cross border migration of the number of RBCs which decreases the ability of marrow to public with Tajikistan [14]. ...
The present study was conducted to show plasmodium species burden and malaria related complications among local population of district Lower Dir, Pakistan (Timergara, Munda, Maidan, Samar Bagh and Talash). During this study a total of 3760 blood samples were taken during January to December 2011, from males (2200,58.5%) and females (1460,41.5%). To detect the plasmodium species, microscopy and rapid diagnostic tests (RDTs) were performed. For the collection of information about the health conditionsof malarial symptomatic patients, questionnaires were also designed.Overall result showed that 12.2% samples were infected, with Plasmodium vivax (94.3%), Plasmodium falciparum (3.9%)and mixed species (P. vivaxand P. falciparum) (1.7%). Seasonal wise prevalence was also checked. Highest infection rate was recorded in autumn (16.5%) followed by summer (13.8%), spring (9.5%) and winter (6.6%). Among people infected with symptoms like severe temperature (9.8%), lower RBCs count (3.7%) and Glucose 6-phosphate dehydrogenase (G-6PD) deficiency (0.6%) were observed. Shortly malaria can be effectively controlled by efforts with an emphasis on improving species diagnosis and treatment availability in district LowerDir, KyberPakhtunkhwa, Pakistan.
... P. falciparum is considered the deadliest parasite, causing the most severe clinical outcomes, whereas P. vivax is the most geographically spread within densely populated regions, thus accentuating the socio-economic burden caused by the disease WHO, 2015). Recently, vivax malaria has re-emerged in regions formerly considered malaria free (Severini et al., 2004;Kim et al., 2009;Bitoh et al., 2011). Worldwide, about 2.85 billion people have been estimated to be at risk of infection by P. vivax Guerra et al., 2010;Battle et al., 2012;Gething et al., 2012). ...
During the last decade, the vast omics field has revolutionized biological research, especially the genomics, transcriptomics and proteomics branches, as technological tools become available to the field researcher and allow difficult question-driven studies to be addressed. Parasitology has greatly benefited from next generation sequencing (NGS) projects, which have resulted in a broadened comprehension of basic parasite molecular biology, ecology and epidemiology. Malariology is one example where application of this technology has greatly contributed to a better understanding of Plasmodium spp. biology and host-parasite interactions. Among the several parasite species that cause human malaria, the neglected Plasmodium vivax presents great research challenges, as in vitro culturing is not yet feasible and functional assays are heavily limited. Therefore, there are gaps in our P. vivax biology knowledge that affect decisions for control policies aiming to eradicate vivax malaria in the near future. In this review, we provide a snapshot of key discoveries already achieved in P. vivax sequencing projects, focusing on developments, hurdles, and limitations currently faced by the research community, as well as perspectives on future vivax malaria research.
... hyrcanus and An. claviger complexes(Severini et al. 2004) (Figure 2). A multiplex polymerase chain reaction (PCR) for ITS-2 was conducted on 15 An. ...
This study reports the mosquito collections conducted in July-August 2013 in Castiglione del Lago (Umbria Region, Italy) during the entomological surveillance within the West Nile national control program. The mosquito collections showed the noteworthy occurrence of Anopheles hyrcanus s.l. (n = 156; 35.8% of the whole sample), a relatively rare mosquito species in Italy, with molecular analyses con rming that these mosquitoes belong to An. hyrcanus s.s. The same catching site was characterized by a relevant richness in mosquito species, in particular the following were found: Anopheles maculipennis s.l. (n = 146; 33.5% composed by 80% Anopheles melanoon, 13.3% Anopheles maculipennis s.s. and 6.7% Anopheles atroparvus), Culex pipiens s.l. (n = 116; 26.6% composed by 90% Cx. p. pipiens, 5% Cx. p. molestus and 5% Cx. p. pipiens/molestus), Culiseta annulata (n = 10; 2.3%), Aedes albopictus (n = 3; 0.7%), and Anopheles claviger (n = 5; 100%).
... (). All isolates were found belong to the VK210 type and alignment of their deduced amino acid sequences revealed 8 different genotypes (or sub-types) and, in particular, 67% of the isolates were found to have identical sequences (SEVERINI et al., 2004). Concerning Armenia, only size polymorphism of Pvmsp1 fragments, amplified from Armenian isolates, was evaluated and we have detected 6 different allelic sizes in 13 isolated analyzed (unpublished data). ...
Malaria due to Plasmodium vivax is globally widespread, with an estimated burden of 70-80 million cases annually. Outside of tropical Africa, P. vivax is the most prevalent parasite, accounting for about 50% of all malaria cases in endemic countries of Middle East, Asia, Western Pacific and Latin America. Furthermore, P. vivax infections represent about 1/4 of some 6,500 malaria cases imported annually in temperate countries of Western Europe from which the parasite was eradicated. A research project on P. vivax malaria resurgence in Newly Independent States of the former USSR was launched at the end of year 2000, with the aim of analysing different epidemiological patterns in the area, entitled: "Resurgence of P. vivax malaria in the Newly Independent States: development of innovative tools for monitoring parasite populations spreading, to potentiate surveillance and control of malaria outbreaks". The project's goal was to develop modern parasitology tools for malaria epidemiology studies, and to integrate them into the surveillance health systems of NIS. The project, coordinated by Istituto Superiore di Sanità, Rome, Italy, included six participants: three NIS countries with different malaria situations, namely Armenia, Azerbaijan and Uzbekistan, CNRS in Montpellier and University of Montpellier, France, and WHO-EURO, Copenhagen, Denmark. In the present issue, we reviewed the main results achieved so far within five years of project activities.
... the infected RBCs, sequestration and removal of RBCs by Similarly, Uzbekistan was also faced the same situation the spleen. In addition, release of cytokines may also be where malaria was eliminated; however reappearance of considered as the contributing factor for lowering the the disease result due to the cross border migration of the number of RBCs which decreases the ability of marrow to public with Tajikistan [14]. ...
The present study was conducted to show plasmodium species burden and malaria related complications among local population of district Lower Dir, Pakistan (Timergara, Munda, Maidan, Samar Bagh and Talash). During this study a total of 3760 blood samples were taken during January to December 2011, from males (2200,58.5%) and females (1460,41.5%). To detect the plasmodium species, microscopy and rapid diagnostic tests (RDTs) were performed. For the collection of information about the health conditionsof malarial symptomatic patients, questionnaires were also designed.Overall result showed that 12.2% samples were infected, with Plasmodium vivax (94.3%), Plasmodium falciparum (3.9%)and mixed species (P. vivaxand P. falciparum) (1.7%). Seasonal wise prevalence was also checked. Highest infection rate was recorded in autumn (16.5%) followed by summer (13.8%), spring (9.5%) and winter (6.6%). Among people infected with symptoms like severe temperature (9.8%), lower RBCs count (3.7%) and Glucose 6-phosphate dehydrogenase (G-6PD) deficiency (0.6%) were observed. Shortly malaria can be effectively controlled by efforts with an emphasis on improving species diagnosis and treatment availability in district LowerDir, KyberPakhtunkhwa, Pakistan.
... The high diversity observed at very low transmission may be the result of importation from diverse parasite populations. 6,79 The relationship between P. vivax transmission and genetic diversity is ill defined, especially at very low transmission and this needs further exploration. Multiple independent sources of reintroduction provide the potential for genetic recombination between genetically distinct clones and unless reintroductions are identified early, this may complicate the distinction between local and imported parasites. ...
Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes.
... More possibly, this zone is rushed by Afghanistan refugees and their migration across the border may help the disease transport resulting infection variations (Suleman, 1988). Similar conditions have been reported when malaria was wiped out from Uzbekistan; however the disease reappeared due to the public cross border movement with Tajikistan (Severini et al., 2004). ...
The purpose of this study was to show Plasmodium species burden and symptoms consistent with malaria related complications among preschool going children in North Western part of Pakistan (Timergara, Munda, Maidan, Samar Bagh and Talash). A total of 1312 blood samples were collected during winter, autumn and summer (2011), from males (808, 61.5%) and females (504, 38.4%). Microscopy and rapid diagnostic tests (RDT) were used for the detection of plasmodium species. Questionnaires were also designed to collect information about the health conditions of malarial symptomatic children. Overall data revealed that 6.9% samples were infected, with Plasmodium vivax (96.7%), Plasmodium falciparum (2.1%) and mixed species (P. vivax and P. falciparum) (1.0%). Highest infection rate was recorded in autumn (2.87%) followed by summer (2.45%) and winter (1.73%). Among malaria symptomatic children symptoms like severe temperature (9.85%) lower RBS count (3.7%), Glucose 6-phosphate dehydrogenase (G-6PD) deficiency (0.65%), respiratory distress (0.65%), neonatal sepsis (0.64%) and low birth weight (0.42%) were observed. Shortly malaria control efforts should be taken with an emphasis on improving species diagnosis and treatment availability in district Dir Lower.
... Although rarely lethal, Plasmodium vivax is the most prevalent human malarial parasite outside of Africa (Gething et al. 2012). This parasitic disease has reemerged in many regions of the world that previously were considered to be malariafree (Severini et al. 2004;Kim et al. 2009;Bitoh et al. 2011). There are several biological characteristics that make this parasite particularly resilient and a global health challenge (Mueller et al. 2009;Gething et al. 2012). ...
Plasmodium vivax is the most prevalent human malaria parasite outside of Africa. Yet, studies aimed to identify genes with signatures consistent with natural selection are rare. Here we present a comparative analysis of the pattern of genetic variation of five sequenced isolates of P. vivax and its divergence with two closely related species, Plasmodium cynomolgi and Plasmodium knowlesi, using a set of orthologous genes. In contrast to Plasmodium falciparum, the parasite that causes the most lethal form of human malaria, we did not find significant constraints on the evolution of synonymous sites genome-wide in P. vivax. The comparative analysis of polymorphism and divergence across loci allowed us to identify 87 genes with patterns consistent with positive selection, including genes involved in the "exportome" of P. vivax, which are potentially involved in evasion of the host immune system. Nevertheless, we have found a pattern of polymorphism genome-wide that is consistent with a significant amount of constraint on the replacement changes and prevalent negative selection. Our analyses also show that silent polymorphism tends to be larger towards the ends of the chromosomes, where many genes involved in antigenicity are located, suggesting that natural selection acts not only by shaping the patterns of variation within the genes but it also affects genome organization.
© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
... The bitter reality is that malaria has not been eradicated as Ross predicted (although he did not mention Africa in his prediction), but still kills millions of people every year. Indeed, malaria is reappearing in places that have been free from malaria [135][136][137]. ...
... Ce risque ne concerne donc pas les voyageurs à destination de la Corée du Sud et n'implique donc pas de prophylaxie. Au Proche-Orient, c'est en Turquie que le nombre de cas de paludisme à P. vivax est le plus inquiétant (probablement entre 50 et 100 000/an), mais l'incidence de la maladie est en forte augmentation en Iraq, en Ouzbekistan et persiste à un taux significatif en Iran [11] [12] [13]. En revanche, la transmission du paludisme autour du bassin méditerranéen est faible et limitée à quelques cas de P. vivax en Algérie, en Egypte et dans quelques foyers du sud marocain [14]. ...
P. vivax is supposed to be involved in benign tertian fever, responsible for a non-complicated disease that could be easily treated by standard antimalarial drug regimen. This could be considered as a long-standing paradigm of a non-virulent malaria parasite. When a patient exhibits severe malaria with the vivax parasite, the issue is often to find falciparum. However, with the implementation of molecular diagnosis, it has becoming more evident that vivax parasites could be involved in severe disease with probably a different pathogenesis. Mixed infections are frequent in various parts of Southeast Asian endemic areas and it was speculated that drugs used to treat falciparum could be involved in the development of vivax drug resistance. How should primaquine be used today for the treatment and prophylaxis of vivax malaria? Considering the re-emergence of vivax malaria in several areas, improving the treatment for this disease is certainly an important issue to avoid late episodes and transmission potential.
... In the latter, the project found that anopheline vector density, climate and demographic conditions are highly favourable for malaria transmission. 30 After five years of activities, this project provided scientific data on the distribution and genetics of the anopheline population and geographical dynamics of P. vivax populations. 31 Greece Greece was the last country in Europe to de declared free of autochthonous malaria in 1973. ...
Plasmodium vivax was endemic in temperate areas in historic times up to the middle of last century. Temperate climate P. vivax has a long incubation time of up to 8-10 months, which partly explain how it can be endemic in temperate areas with a could winter. P. vivax disappeared from Europe within the last 40-60 years, and this change was not related to climatic changes. The surge of P. vivax in Northern Europe after the second world war was related to displacement of refugees and large movement of military personnel exposed to malaria. Lately P. vivax has been seen along the demilitarized zone in South Korea replication a high endemicity in North Korea. The potential of transmission of P. vivax still exist in temperate zones, but reintroduction in a larger scale of P. vivax to areas without present transmission require large population movements of P. vivax infected people. The highest threat at present is refugees from P. vivax endemic North Korea entering China and South Korea in large numbers.
... DNA extraction (Purelink TM Genomic DNA Kit -Invitrogen) was done on one whole blood-spot on filter paper from each of the following compartments: maternal peripheral blood at delivery, placental and cord blood, and neonate's blood at the time of birth and during hospital admission. Plasmodium vivax infection was detected by conventional PCR for specific P. vivax merozoite surface protein 1 gene (Pvmsp1) in all samples except in the newborn's blood at the time of birth (Figure 1) [19]. Also, confirmation of the presence of P. vivax and absence of P. falciparum infection was carried out on all samples by Real-Time PCR with a LightCycler W 480 system (Roche). ...
This is a report of the first Plasmodium vivax congenital malaria case in Guatemala and the first case in Latin America with genotypical, histological and clinical characterization. The findings show that maternal P. vivax infection still occurs in areas that are in the pathway towards malaria elimination, and can be associated with detrimental health effects for the neonate. It also highlights the need in very low transmission areas of not only maintaining, but increasing awareness of the problem and developing surveillance strategies, based on population risk, to detect the infection especially in this vulnerable group of the population.
... Uzbekistan Severini et al. 2004 [48] ...
Traditionally, infection with Plasmodium vivax was thought to be benign and self-limiting, however, recent evidence has demonstrated that infection with P. vivax can also result in severe illness and death. Research into P. vivax has been relatively neglected and much remains unknown regarding the biology, pathogenesis and epidemiology of this parasite. One of the fundamental factors governing transmission and immunity is parasite diversity. An understanding of parasite population genetic structure is necessary to understand the epidemiology, diversity, distribution and dynamics of natural P. vivax populations. In addition, studying the population structure of genes under immune selection also enables investigation of the dynamic interplay between transmission and immunity, which is crucial for vaccine development. A lack of knowledge regarding the transmission and spread of P. vivax has been particularly highlighted in areas where malaria control and elimination programmes have made progress in reducing the burden of Plasmodium falciparum, yet P. vivax remains as a substantial obstacle. With malaria elimination back on the global agenda, mapping of global and local P. vivax population structure is essential prior to establishing goals for elimination and the roll-out of interventions. A detailed knowledge of the spatial distribution, transmission and clinical burden of P. vivax is required to act as a benchmark against which control targets can be set and measured. This paper presents an overview of what is known and what is yet to be fully understood regarding P. vivax population genetics, as well as the importance and application of P. vivax population genetics studies.
... In central Asia-A. superpictus, Anopheles pulcherrimus, Anopheles hyrcanus, and A. sacharovi (Severini et al. 2004;Temel 2004), in South Asia (India, Nepal, Bhutan, Bangladesh, Maldives, Sri Lanka, and Indonesia)-A. stephensi, A. culicifacies, Anopheles fluviatilis, Anopheles minimus, Anopheles dirus, Anopheles (Kiszewski et al. 2004) aconitus, and Anopheles maculatus (Al-Tikrity 1964;Utarini et al. 2003;Klinkenberg et al. 2004b;Sharma et al. 2006a, b) and in East and South-East Asia (Myanmar, Laos, Vietnam, Malaysia, Cambodia, Singapore, Brunei, and Philippines) the malaria vectors are A. minimus, A. dirus, Anopheles sundaicus, A. maculatus, Anopheles subpictus, and Anopheles flavirostris (Torres et al. 1997;Soe-Soe et al. 2001;Kobayashi et al. 2004;Chatterjee 2005;Vythilingam et al. 2005;Erhart et al. 2007;Dysoley et al. 2008;Ngo et al. 2008;Shirayama et al. 2008). ...
Malaria is one of the most common vector-borne diseases widespread in the tropical and subtropical regions. Despite considerable success of malaria control programs in the past, malaria still continues as a major public health problem in several countries. Vector control is an essential part for reducing malaria transmission and became less effective in recent years, due to many technical and administrative reasons, including poor or no adoption of alternative tools. Of the different strategies available for vector control, the most successful are indoor residual spraying and insecticide-treated nets (ITNs), including long-lasting ITNs and materials. Earlier DDT spray has shown spectacular success in decimating disease vectors but resulted in development of insecticide resistance, and to control the resistant mosquitoes, organophosphates, carbamates, and synthetic pyrethroids were introduced in indoor residual spraying with needed success but subsequently resulted in the development of widespread multiple insecticide resistance in vectors. Vector control in many countries still use insecticides in the absence of viable alternatives. Few developments for vector control, using ovitraps, space spray, biological control agents, etc., were encouraging when used in limited scale. Likewise, recent introduction of safer vector control agents, such as insect growth regulators, biocontrol agents, and natural plant products have yet to gain the needed scale of utility for vector control. Bacterial pesticides are promising and are effective in many countries. Environmental management has shown sufficient promise for vector control and disease management but still needs advocacy for inter-sectoral coordination and sometimes are very work-intensive. The more recent genetic manipulation and sterile insect techniques are under development and consideration for use in routine vector control and for these, standardized procedures and methods are available but need thorough understanding of biology, ethical considerations, and sufficiently trained manpower for implementation being technically intensive methods. All the methods mentioned in the review that are being implemented or proposed for implementation needs effective inter-sectoral coordination and community participation. The latest strategy is evolution-proof insecticides that include fungal biopesticides, Wolbachia, and Denso virus that essentially manipulate the life cycle of the mosquitoes were found effective but needs more research. However, for effective vector control, integrated vector management methods, involving use of combination of effective tools, is needed and is also suggested by Global Malaria Control Strategy. This review article raises issues associated with the present-day vector control strategies and state opportunities with a focus on ongoing research and recent advances to enable to sustain the gains achieved so far.
... Again, no primary data were found describing biting location. However, An. superpictus appears to be opportunistic in its feeding habits and will enter houses to feed [250], but is generally regarded as exophagic [318,319]. ...
This is the second in a series of three articles documenting the geographical distribution of 41 dominant vector species (DVS) of human malaria. The first paper addressed the DVS of the Americas and the third will consider those of the Asian Pacific Region. Here, the DVS of Africa, Europe and the Middle East are discussed. The continent of Africa experiences the bulk of the global malaria burden due in part to the presence of the An. gambiae complex. Anopheles gambiae is one of four DVS within the An. gambiae complex, the others being An. arabiensis and the coastal An. merus and An. melas. There are a further three, highly anthropophilic DVS in Africa, An. funestus, An. moucheti and An. nili. Conversely, across Europe and the Middle East, malaria transmission is low and frequently absent, despite the presence of six DVS. To help control malaria in Africa and the Middle East, or to identify the risk of its re-emergence in Europe, the contemporary distribution and bionomics of the relevant DVS are needed.
A contemporary database of occurrence data, compiled from the formal literature and other relevant resources, resulted in the collation of information for seven DVS from 44 countries in Africa containing 4234 geo-referenced, independent sites. In Europe and the Middle East, six DVS were identified from 2784 geo-referenced sites across 49 countries. These occurrence data were combined with expert opinion ranges and a suite of environmental and climatic variables of relevance to anopheline ecology to produce predictive distribution maps using the Boosted Regression Tree (BRT) method.
The predicted geographic extent for the following DVS (or species/suspected species complex*) is provided for Africa: Anopheles (Cellia) arabiensis, An. (Cel.) funestus*, An. (Cel.) gambiae, An. (Cel.) melas, An. (Cel.) merus, An. (Cel.) moucheti and An. (Cel.) nili*, and in the European and Middle Eastern Region: An. (Anopheles) atroparvus, An. (Ano.) labranchiae, An. (Ano.) messeae, An. (Ano.) sacharovi, An. (Cel.) sergentii and An. (Cel.) superpictus*. These maps are presented alongside a bionomics summary for each species relevant to its control.
... vivax in different populations. [16][17][18][19][20][21][22][23] However, investigations on polymorphism of the whole pvmsp1 have until now been limited. 13 In this study, we report polymorphism of pvmsp1 from isolates in Sanliurfa, southeastern Turkey, where malaria has long been one of the most common infectious diseases and P. vivax has continuously been identified as the only Plasmodium species. ...
The 200-kD merozoite surface protein of Plasmodium vivax (PvMSP-1) is one of the leading vaccine candidates against P. vivax malaria. However, the gene encoding PvMSP-1 (pvmsp1) is highly polymorphic and is a major obstacle to effective vaccine development. To further understand polymorphism in pvmsp1, we obtained 30 full-length pvmsp1 sequences from southeastern Turkey. Comparative analysis of sequences from Turkey and other areas showed substantially limited polymorphism. Substitutions were found at 280 and 162 amino acid sites in samples from other regions and those from Turkey, respectively. Eight substitutions were unique to Turkey. In one of them, D/E at position 1706 in the C-terminal 19-kD region, the K/E change at 1709 was the only polymorphism previously known. Limited diversity was also observed in microsatellites. Data suggest a recent population bottleneck in Turkey that may have obscured a signature for balancing selection in the C-terminal 42-kD region, which was otherwise detectable in other areas.
... Plasmodium vivax is widely distributed and characterized by relapses that generate a significant socio-economic burden (Mendis et al., 2001) in countries such as Brazil, Sri Lanka and Colombia where this species is most prevalent. This parasite re-appeared in Asian countries such as Uzbekistan (Severini et al., 2004 ), Azerbaijan (Leclerc et al., 2004), Turkey (Zeyrek et al., 2008), north of Iran (Zakeri et al., 2004), and the Republic of Korea (Lim et al., 2000) where eradication efforts had been successful in 1960s. Growing chloroquine and primaquine resistance strains of P. vivax in malaria endemic regions (Barat and Bloland, 1997; Nomura et al., 2001) could call for new tools and strategies to combat P. vivax. ...
The C-terminal region of Plasmodium vivax merozoite surface protein 1 (PvMSP-1(19)) is a leading vaccine candidate for inclusion in a polyvalent malaria vaccine. In the present study, the IgG subclasses profile and the avidity of IgG to PvMSP-1(19) were evaluated in individuals (n=94) naturally exposed to P. vivax parasite in malaria endemic areas in Chabahar districts, Iran. In individuals with patent P. vivax malaria, 86.1% was sero-positive to PvMSP-1(19) and IgG1 (81.9%) was the predominant subclass. In addition, to determine the persistence of specific IgG, IgG1 and IgG3 antibodies to PvMSP-1(19), the frequency of antibodies was determined in the infected subjects (n=74) after treatment with standard chloroquine and it was detected that the frequency of responders was significantly reduced to 51.3%, 51% and 16.2%, respectively. The antigen-binding avidity of IgG antibodies to PvMSP-1(19) was measured in sero-positive sera and the high-avidity of IgG, IgG1 and IgG3 was found in 66.6%, 61% and 47% of the infected subjects with P. vivax, respectively. The present result shows that individuals who exposed to vivax malaria in the endemic region in Iran develop antibodies with high-avidity to PvMSP-1(19). These results could help to understand the interactions between the host and P. vivax parasite in development of MSP-1(19)-based vaccine.
... In fact, some resident sources suggested that health services are under pressure from communities to keep the case number statistics low, since rice growing was prohibited by the regional government within a buffer zone of several km around inhabited areas in 2002. [21,40,41]. An. superpictus and An. ...
Reported malaria cases in rice growing areas in western Tajikistan were at the root of a rapid appraisal of the local malaria situation in a selected agro-ecological setting where only scarce information was available. The rapid appraisal was complemented by a review of the epidemiology and control of malaria in Tajikistan and Central Asia from 1920 until today. Following a resurgence in the 1990s, malaria transmission has been reduced considerably in Tajikistan as a result of concerted efforts by the government and international agencies. The goal for 2015 is transmission interruption, with control interventions and surveillance currently concentrated in the South, where foci of Plasmodium vivax and Plasmodium falciparum persist.
The rapid malaria appraisal was carried out in six communities of irrigated rice cultivation during the peak of malaria transmission (August/September 2007) in western Tajikistan. In a cross-sectional survey, blood samples were taken from 363 schoolchildren and examined for Plasmodium under a light microscope. A total of 56 farmers were interviewed about agricultural activities and malaria. Potential Anopheles breeding sites were characterized using standardized procedures. A literature review on the epidemiology and control of malaria in Tajikistan was conducted.
One case of P. vivax was detected among the 363 schoolchildren examined (0.28%). The interviewees reported to protect themselves against mosquito bites and used their own concepts on fever conditions, which do not distinguish between malaria and other diseases. Three potential malaria vectors were identified, i.e. Anopheles superpictus, Anopheles pulcherrimus and Anopheles hyrcanus in 58 of the 73 breeding sites examined (79.5%). Rice paddies, natural creeks and man-made ponds were the most important Anopheles habitats.
The presence of malaria vectors and parasite reservoirs, low awareness of, and protection against malaria in the face of population movements and inadequate surveillance may render local communities vulnerable to potential epidemics. To attain malaria transmission interruption in Tajikistan by 2015, there is a need for rigorous surveillance along with strengthening of primary health care facilities for effective case management, and possibly a more differentiated vector control strategy based on additional local evidence.
... The phylogenetic trees based on the ITS2 and D3 sequences indicated that these four species are indeed closely related, having a high degree of sequence similarity (Figure 1). Moreover, the evidence of genetic distance and sequence similarity obtained between the A. annularis group of mosquitoes and two unidentified Anopheles species, RGS-2 and RGS-3, predict that these species, along with the A. pulcherrimus and A. maculatus group of mosquitoes, are also closely linked (Severini et al., 2004;Sharpe et al., 1999). ...
The Anopheles annularis group of mosquitoes is widely distributed in Southeast Asia and may be locally important as malaria vectors. Members of this group are morphologically very similar and often difficult to distinguish, particularly A. nivipes and A. philippinensis. We report the sequence analysis of the rDNA internal transcribed spacer 2 (ITS2) and Domain-3 (D3) regions of the four members of the A. annularis group -A. nivipes, A. philippinensis, A. annularis and A. pallidus - and a method for their molecular identification. No intraspecies sequence variation was detected among the specimens, while interspecific sequence differences were greater for ITS2 than the D3 regions. Comparison of the D3 sequences of the four species revealed two SmaI restriction sites in A. nivipes, but only one site in A. philippinensis, A. annularis and A. pallidus. The ApaI site was present in both A. philippinensis and A. pallidus, while an NcoI site was present in A. pallidus only. Restriction digestion of the PCR products of D3 fragment individually with SmaI, ApaI and NcoI produced a distinctive pattern for all the four species. We present, for the first time, a PCR-RFLP method to distinguish the four members of the A. annularis group of mosquitoes.
... Au Proche-Orient, c'est en Turquie que le nombre de cas de paludisme à P. vivax est le plus inquiétant (probablement entre 50 et 100 000/an), mais l'incidence de la maladie est en forte augmentation en Iraq, en Ouzbekistan et persiste à un taux significatif en Iran [11][12][13]. En revanche, la transmission du paludisme autour du bassin méditerranéen est faible et limitée à quelques cas de P. vivax en Algérie, en Egypte et dans quelques foyers du sud marocain [14]. ...
P. vivax is supposed to be involved in benign tertian fever, responsible for a non-complicated disease that could be easily treated by standard antimalarial drug regimen. This could be considered as a long-standing paradigm of a non-virulent malaria parasite. When a patient exhibits severe malaria with the vivax parasite, the issue is often to find falciparum. However, with the implementation of molecular diagnosis, it has becoming more evident that vivax parasites could be involved in severe disease with probably a different pathogenesis. Mixed infections are frequent in various parts of Southeast Asian endemic areas and it was speculated that drugs used to treat falciparum could be involved in the development of vivax drug resistance. How should primaquine be used today for the treatment and prophylaxis of vivax malaria? Considering the re-emergence of vivax malaria in several areas, improving the treatment for this disease is certainly an important issue to avoid late episodes and transmission potential.
... (gt): genotypes correspond to the RFLP genotypes seen in Fig. 3. Numbers on the left: 1 and 2, Ardebil (adult form with spot on palpi); 5, 10, and 12, Ardebil (adult form without spot on palpi); 3, Fars; 4, Lorestan (atypical larval form); 6, Khorasan Razavi; 7 and 8, Lorestan (typical larval form); 9 and 11, Zanjan; 13, Qum; 14, Kerman; 15-18, Sistan-Baluchistan. The numbers above sequences refer to the position of substitution in the COI portion and dash (-) means identical to the first line. of transmission of malaria throughout the region Severini et al., 2004). For instance, the border areas of Iran with Azerbaijan, Armenia, and Turkey were considered malaria free, in 1991. ...
Anopheles superpictus has been implicated as the most widespread malaria vector in Iran. We collected adult specimens from eight provinces across the country and subjected them to a morphological investigation as well as molecular analysis of mitochondrial DNA COI-COII region, using PCR-RFLP and analysis of DNA sequence alignment for 708bp of the COI locus. Two distinct morphological forms (A and B) of the species were found sympatric in all areas of study. PCR-RFLP using AluI separated the specimens into at least three genotypes (X, Y, and Z), and alignment of DNA sequences revealed a 12.3% variation in the COI region between the genotypes. However, the sequence variation does not correspond to the morphological forms. Our observations suggest that A. superpictus in Iran is likely a group species. However, further ecological, molecular, cytological, and epidemiological studies are necessary to clear the status of the taxon and the potential role of each putative species in the transmission of malaria.
... Plasmodium vivax is a major public health challenge in Central and South America; the Middle East; Central, South, and Southeast Asia; Oceania; and East Africa, where 2.6 billion people are currently at risk of infection (11), and 70 to 80 million clinical cases are reported each year (22). This human pathogen reappeared in Asian countries where eradication efforts had been successful in the 1960s, such as Uzbekistan (30), Azerbaijan (16), and the Republic of Korea (18). In Brazil, P. vivax surpassed Plasmodium falciparum two decades ago as the main cause of malaria morbidity across the Amazon Basin (19) and caused 80% of the 600,000 malaria cases reported in that country in 2005 (Ministry of Health of Brazil, unpublished data). ...
Merozoite surface protein 1 of Plasmodium vivax (PvMSP-1), a major target for malaria vaccine development, contains six highly polymorphic domains interspersed with conserved sequences. Although there is evidence that the sequence divergence in PvMSP-1 has been maintained over 5 million years by balanced selection exerted by the host's acquired immunity, the variant specificity of naturally acquired antibodies to PvMSP-1 remains poorly investigated. Here, we show that 15 recombinant proteins corresponding to PvMSP-1 variants commonly found in local parasites were poorly recognized by 376 noninfected subjects aged 5 to 90 years exposed to malaria in rural Amazonia; less than one-third of them had detectable immunoglobulin G (IgG) antibodies to at least one variant of blocks 2, 6, and 10 that were expressed, although 54.3% recognized the invariant 19-kDa C-terminal domain PvMSP-1(19). Although the proportion of responders to PvMSP-1 variants increased substantially during subsequent acute P. vivax infections, the specificity of IgG antibodies did not necessarily match the PvMSP-1 variant(s) found in infecting parasites. We discuss the relative contribution of antigenic polymorphism, poor immunogenicity, and original antigenic sin (the skew in the specificity of antibodies elicited by exposure to new antigenic variants due to preexisting variant-specific responses) to the observed patterns of antibody recognition of PvMSP-1. We suggest that antibody responses to the repertoire of variable domains of PvMSP-1 to which subjects are continuously exposed are elicited only after several repeated infections and may require frequent boosting, with clear implications for the development of PvMSP-1-based subunit vaccines.
... the 1960s, such as Uzbekistan (Severini et al., 2004), Azerbaijan (Leclerc et al., 2004b) and the Republic of Korea (Lim et al., 2000). In addition, P. vivax has recently surpassed P. falciparum as the main cause of malaria morbidity across the Amazon Basin of Brazil (Loiola et al., 2002). ...
The population structure of Plasmodium vivax remains elusive. The markers of choice for large-scale population genetic studies of eukaryotes, short tandem repeats known as microsatellites, have been recently reported to be less polymorphic in P. vivax. Here we investigate the microsatellite diversity and geographic structure in P. vivax, at both local and global levels, using 14 new markers consisting of tri- or tetranucleotide repeats. The local-level analysis, which involved 50 field isolates from Sri Lanka, revealed unexpectedly high diversity (average virtual heterozygosity [H(E)], 0.807) and significant multilocus linkage disequilibrium in this region of low malaria endemicity. Multiple-clone infections occurred in 60% of isolates sampled in 2005. The global-level analysis of field isolates or monkey-adapted strains identified 150 unique haplotypes among 164 parasites from four continents. Individual P. vivax isolates could not be unambiguously assigned to geographic populations. For example, we found relatively low divergence among parasites from Central America, Africa, Southeast Asia and Oceania, but substantial differentiation between parasites from the same continent (South Asia and Southeast Asia) or even from the same country (Brazil). Parasite relapses, which may extend the duration of P. vivax carriage in humans, are suggested to facilitate the spread of strains across continents, breaking down any pre-existing geographic structure.
There are close to 4000 mosquito species in the world, of which over 400 are Anopheles (Tyagi et al. 2015). Different deserts of the world are essentially characterized by, more or less, but not exclusive, a group of specific, yet preponderant, malaria vectors which are highly adapted to xeric environments, such as Anopheles stephensi in Asia and the Middle East deserts, and An. arabiensis in the Arabian Peninsula and the Sahara deserts. Both these vector mosquitoes tolerate drier environments and are, therefore, absent from the sylvatic environments. Ironically, very little is known about the desert malaria vectors’ biology and distribution. Both these vector species present a higher inclination for human blood and susceptibility toward Plasmodium falciparum and P. vivax. Anopheles stephensi mysorensis strain has been demonstrated to possess high competency for Plasmodium vivax. Additionally, presence of inhibitory carbohydrates in An. stephensi mysorensis and their role in blocking sporogonic cycle in Plasmodium vivax has been also recorded (Basseri et al. 2008).
The Asia-Pacific region faces formidable challenges in achieving malaria elimination by the proposed target in 2030. Molecular surveillance of Plasmodium parasites can provide important information on malaria transmission and adaptation, which can inform national malaria control programmes (NMCPs) in decision-making processes. In November 2019 a parasite genotyping workshop was held in Jakarta, Indonesia, to review molecular approaches for parasite surveillance and explore ways in which these tools can be integrated into public health systems and inform policy. The meeting was attended by 70 participants from 8 malaria-endemic countries and partners of the Asia Pacific Malaria Elimination Network. The participants acknowledged the utility of multiple use cases for parasite genotyping including: quantifying the prevalence of drug resistant parasites, predicting risks of treatment failure, identifying major routes and reservoirs of infection, monitoring imported malaria and its contribution to local transmission, characterizing the origins and dynamics of malaria outbreaks, and estimating the frequency of Plasmodium vivax relapses. However, the priority of each use case varies with different endemic settings. Although a one-size-fits-all approach to molecular surveillance is unlikely to be applicable across the Asia-Pacific region, consensus on the spectrum of added-value activities will help support data sharing across national boundaries. Knowledge exchange is needed to establish local expertise in different laboratory-based methodologies and bioinformatics processes. Collaborative research involving local and international teams will help maximize the impact of analytical outputs on the operational needs of NMCPs. Research is also needed to explore the cost-effectiveness of genetic epidemiology for different use cases to help to leverage funding for wide-scale implementation. Engagement between NMCPs and local researchers will be critical throughout this process.
The global occurrences of malaria make it the major killer among all diseases. Many initiatives are being taken worldwide to control the disease. But, despite all these initiatives, its incidences are increasing constantly. Antimalarial drug resistance and lack of method to assess efficacy of any control initiatives have also worsen the situation. In this scenario phylogenetic study of malaria pathogen, can be effective in helping to develop new drugs and vaccines for the disease as well as to understand host parasite interactions and evolution of drug resistance in the pathogen. Malaria is likely originated in tropical Africa and later spread to other parts of the world due to human movement. Presence of plastid in Plasmodium sp. indicates its affinity with cynobacteria and green algae. Recent phylogenetic studies have indicated that all the four human malaria sp. are remotely related to each other. Close relation between P. falciparum and chimpanzee malaria parasite (P. reichenowi) and P. vivax and malaria parasite species of Asian monkeys has been observed. P. vivax shows higher genomic diversity than P. falciparum which indicates that it is older than the latter. Evolutionary studies suggest origin of P. falciparum and P. vivax in Africa and Asia respectively, and support ancient population expansions for both Plasmodium sp. Resistance in Plasmodium sp. for widely used antimalarial drugs was also developed along with spread of the disease It is Darwin’s fundamental contribution that fired the imagination of scientist’s interest in evolutionary studies, and these studies have already proved of much value in understanding the origin, spread and control measures in malaria.
Protocol S1. Sources and Descriptions of Medical Intelligence Used to Describe the PfAPI
doi:10.1371/journal.pmed.0050038.sd001
Protocol S2. Developing Global Biological Limits for P. falciparum Transmission
doi:10.1371/journal.pmed.0050038.sd002
Table S1. National Estimates of Population at Risk of P. falciparum Malaria in 2007
doi:10.1371/journal.pmed.0050038.st001
Plasmodium vivax is still the more prevalent human Plasmodium outside Africa and despite this fact, there is still a deep lack of knowledge on its biology. Metacaspases are cysteine proteases related to metazoan caspases, involved in programmed cell death. Here, we have characterized the P. vivax metacaspase 1 gene in a total of 63 vivax isolates, 32 isolates collected in southern Iran and 31 Italian imported isolates originating from 12 different endemic countries. We have firstly identified DNA size polymorphism in P. vivax metacaspase 1 gene. A total of four different allelic sizes were found, resulting from the insertion of 1 to 4 tandem repeat units located within the intronic region of the P. vivax metacaspase 1. Similarly, we also have identified four distinct allelic types by using vivax merozoite surface protein-1 size polymorphism analysis.
Malaria is still one of the most important health-problems in the world and is endemic in Iran. Since 1994, after collapse of former Soviet Union, a new threat of malaria importation emerged from those countries into the northern Iran. This work was carried out to provide further evidence on the status of anopheline species composition, the malaria parasite species, and natural infectivity of mosquitoes distributed in Pars-Abad district, on the borderline of Azerbaijan in northwestern Iran. Mosquitoes were collected from May to December 2008 in anopheline seasonal activity and were identified at the species level. The genus- and species-specific primers against Plasmodium ssrDNA gene were used for specific amplification on female mosquito head+thorax. Members of the Anoheles maculipennis complex were identified by sequence analysis of the ribosomal internal transcribed spacer II (ITS2-rDNA). Morphological character-based identification showed that out of 1455 anopheline female specimens, 1121 (77%) were of A. maculipennis s.l. and 334 (23%) were of Anoheles hyrcanus. Molecular analysis of the species complex indicated the presence of Anoheles sacharovi 984 (67.6%) and A. maculipennis 137 (9.4%) in the region. None of themosquito's head-thorax was found to be naturally infected by malaria parasite. Results of this study, particularly high dominance of A. sacharovi, suggest a potential risk of malaria epidemic in the region, and the need for a continuous epidemiological surveillance.
Genetic diversity and population structure of Plasmodium vivax parasites can predict the origin and spread of novel variants within a population enabling population specific malaria control measures. We analyzed the genetic diversity and population structure of 425 P. vivax isolates from Sri Lanka, Myanmar, and Ethiopia using 12 trinucleotide and tetranucleotide microsatellite markers. All three parasite populations were highly polymorphic with 3-44 alleles per locus. Approximately 65% were multiple-clone infections. Mean genetic diversity (H(E)) was 0.7517 in Ethiopia, 0.8450 in Myanmar, and 0.8610 in Sri Lanka. Significant linkage disequilibrium was maintained. Population structure showed two clusters (Asian and African) according to geography and ancestry. Strong clustering of outbreak isolates from Sri Lanka and Ethiopia was observed. Predictive power of ancestry using two-thirds of the isolates as a model identified 78.2% of isolates accurately as being African or Asian. Microsatellite analysis is a useful tool for mapping short-term outbreaks of malaria and for predicting ancestry.
Malaria in South America is a major public health problem. In Brazil, most of the cases occur in the Amazon Region, particularly in the State of Amazonas. In Manaus, the capital of Amazonas, atypical cases of Plasmodium vivax infections, including patients presenting with severe thrombocytopenia and bleeding, led to the hypothesis that severe disease could be related to a particular, emergent, and more pathogenic genotype of P. vivax. The authors describe the epidemiology of malaria for the Amazonas State and city of Manaus by comparing patients admitted in the hospital to those treated as outpatients in the Fundacao de Medicina Tropical do Amazonas. Admissions due to vivax malaria increased significantly from 1997 through 2003, suggesting a change in clinical presentation. The admitted group presented higher mean parasite counts, lower platelet counts, and higher levels of liver enzymes, higher total and indirect bilirubin, and higher blood urea nitrogen when compared to the outpatient group. Clinical symptoms of severe disease, including hematuria, hemolytic anemia, and thrombocytopenia were only noted in the admitted group. Furthermore, the presence of a palpable liver was more frequent in admitted patients. Nucleic acid sequences of three genes from P. vivax, the 18S SSUrRNA Type A gene, CSP gene, and MSP-1 gene were determined. Strains from test samples were compared to each other, to the reference strains Salvador I and Belem, and to sequences retrieved from the Gene Bank. It was not possible to demonstrate the evolutionary relationship among our test samples by tests of phylogeny that incorporated sequence data for all three genes tested. The factors that may have limited the power of a combined analysis include small sample size and differences in the mechanisms and extent of variation among the genes. The retrospective study was unable to demonstrate that a particular strain of P. vivax was responsible for severe disease requiring hospitalization.
Vector-borne diseases such as malaria, dengue, and leishmaniasis are a threat to military forces deployed outside of the United States. The availability of specific information on the vector-borne disease threat (e.g., presence or absence of a specific disease agent, temporal and geographic distribution of competent vectors, and vector infection rates) allows for effective implementation of appropriate measures to protect our deployed military forces. Vector diagnostics can provide critical, real-time information crucial to establishing effective vector prevention/control programs. In this article we provide an overview of current vector diagnostic capabilities, evaluate the use of vector diagnostics in Operation Enduring Freedom and Operation Iraqi Freedom, and discuss the concept of operations under which vector diagnostics are employed.
The prospect of malaria eradication has been raised recently by the Bill and Melinda Gates Foundation with support from the international community. There are significant lessons to be learned from the major successes and failures of the eradication campaign of the 1960s, but cessation of transmission in the malaria heartlands of Africa will depend on a vaccine and better drugs and insecticides. Insect control is an essential part of reducing transmission. To date, two operational scale interventions, indoor residual spraying and deployment of long-lasting insecticide-treated nets (LLINs), are effective at reducing transmission. Our ability to monitor and evaluate these interventions needs to be improved so that scarce resources can be sensibly deployed, and new interventions that reduce transmission in a cost-effective and efficient manner need to be developed. New interventions could include using transgenic mosquitoes, larviciding in urban areas, or utilizing cost-effective consumer products. Alongside this innovative development agenda, the potential negative impact of insecticide resistance, particularly on LLINs, for which only pyrethroids are available, needs to be monitored.
In this study, the nature and extent of genetic diversity of Plasmodium vivax populations circulating in Afghanistan have been investigated by analyzing three genetic markers: csp, msp-1, and msp-3 alpha. Blood samples (n=202) were collected from patients presenting with vivax malaria from south-western (Herat) and south-eastern (Nangarhar) parts of Afghanistan, and analysed using nested-PCR/RFLP and sequencing methods. Genotyping pvmsp-1 revealed type 1, type 2 and recombinant type 3 allelic variants, with type 1 predominant in parasites in both study areas. The sequence analysis of 57 P. vivax isolates identified a total of 26 distinct alleles. Genotyping pvcsp gene showed that VK210 type (86.6%) is predominant in Afghanistan. Moreover, three major types of the pvmsp-3 alpha locus: type A, type B and type C were distinguished among Afghani isolates. The predominant fragments among Nangarhar and Herat parasites were type A (70.8% and 67.9%, respectively). PCR/RFLP products with Hha I and Alu I were detected 52 and 38 distinct variants among Nangarhar and Herat isolates, respectively. These results strongly indicate that the P. vivax populations in Afghanistan are highly diverse.
The merozoite surface protein-1 (MSP-1) of Plasmodium vivaxexhibits great antigenic diversity among different isolates of this parasite. This antigen is a useful genetic marker for studying the polymorphism of natural P. vivax parasite populations. One or more of these populations has been responsible for resurgent malaria now occurring in Korea. This paper reports the analysis of a highly polymorphic region between interspecies conserved blocks 5 and 6 of the MSP-1 gene, using the polymerase chain reaction to amplify the DNA fragment encompassing these regions from 25 Korean isolates, followed by sequencing. Almost all amino acid sequences of Korean isolates were nearly identical to that of Thai isolates TD525A (96.6-99.7%) and TD424 (96.3-99.5%), and very similar to that of the France-Belem strain when compared with other isolates (Sal-1, Sri Lanka, and Colombia). Interallelic recombination was found in the poly-Q repeat and a Sal-1 type amino acid structure was observed in all isolates. This study shows that the MSP gene nucleotide sequence of resurgent P. vivax in Korea is most similar to that of Thai isolates; however, the Korean strains are phylogenetically unique.
Plasmodium vivax has hepatocytic dormant stages, hypnozoites, that cause relapses. This work compared paired isolates fromprimary attacks
and relapses obtained from 10 individuals in Brazil using the merozoite surface protein 1 gene, PvMSP1, as a genetic marker.
Four samples from primary attacks contained genetically mixed parasites harboring the 2 major PvMSP1 allelic forms. PCR revealed
the presence of these 2 forms in the relapse parasites of 2 patients, demonstrating that the activation of hypnozoites is
not clonal. DNA sequences from paired primary/relapse samples demonstrated that the parasites from the primary attack are
identical to those in relapse samples in which the same allele forms were detected in both infections. Studies on the naturally
acquired humoral immune responses of these patients against a recombinant protein expressing the C-terminus PvMSP1 demonstrated
an increase in the titers, affinity maturation, and predominance of the IgG1 subclass during the relapse.
Plasmodium vivax has hepatocytic dormant stages, hypnozoites, that cause relapses. This work compared paired isolates from primary attacks and relapses obtained from 10 individuals in Brazil using the merozoite surface protein 1 gene, PvMSP1, as a genetic marker. Four samples from primary attacks contained genetically mixed parasites harboring the 2 major PvMSP1 allelic forms. PCR revealed the presence of these 2 forms in the relapse parasites of 2 patients, demonstrating that the activation of hypnozoites is not clonal. DNA sequences from paired primary/relapse samples demonstrated that the parasites from the primary attack are identical to those in relapse samples in which the same allele forms were detected in both infections. Studies on the naturally acquired humoral immune responses of these patients against a recombinant protein expressing the C-terminus PvMSP1 demonstrated an increase in the titers, affinity maturation, and predominance of the IgG1 subclass during the relapse.
This study presents an analysis of imported malaria cases for the period 1971-1997 in the 51 countries belonging to the WHO European Region. The number of cases has been steadily increasing, reaching 12,860 in 1997. France, United Kingdom and Germany account for nearly 70% of the imported cases. The proportion of Plasmodium falciparum cases has dramatically increased in the last 10 years and this species is presently responsible for approximately 70% of all imported cases. Relatively high fatality rates for P. falciparum are present in some EU countries: Germany reported 25 fatal cases in 1995, France; 21 in 1996, United Kingdom; 13 in 1997 and Italy reported 12 fatal cases in 1997.
Although most of the Papua New Guinea highlands are too high for stable malaria transmission, local epidemics are a regular feature of the region. Few detailed descriptions of such epidemics are available, however. We describe the investigation of a malaria epidemic in the Obura Valley, Eastern Highlands Province, Papua New Guinea. Of the 244 samples examined by microscopy, 6.6% were positive for Plasmodium falciparum only, 9.4% were positive for Plasmodium vivax only, and 1.2% were mixed infections. MSP2 and MSP3alpha genotyping and AMA1 sequencing were used to determine the genetic variation present in a sample of P. falciparum and P. vivax infections. The P. vivax infections were found to be genetically highly diverse. In contrast, all P. falciparum samples were of a single genotype. This striking difference in genetic diversity suggests endemic, low-level local transmission for P. vivax but an outside introduction of P. falciparum as the most likely source of the epidemic.
Molecular cloning and structure analysis of the gene encoding the Pv200 protein of the Sal-1 strain of Plasmodium vivax revealed an overall identity of 34-37% when the deduced amino acid sequence was compared with the sequences of various major merozoite surface antigens of Plasmodium falciparum, Plasmodium yoelii and Plasmodium chabaudi. When the Sal-1 Pv200 sequence was compared with the corresponding sequence from the Belèm strain of P. vivax, it was found that the two merozoite surface antigens were relatively well conserved with an overall amino acid sequence identity of 81%. A region of 23 repeated glutamine residues, found in the sequence of the Belèm isolate was not found, however, in the Sal-1 sequence. Amino- and carboxy-terminal domains of the Pv200 protein were expressed in the yeast Saccharomyces cerevisiae. Each recombinant protein was shown to react with antibodies in sera from splenectomized Bolivian Saimiri monkeys that had been infected previously with P. vivax, and in human sera from individuals with a history of exposure to vivax malaria. The availability of recombinant DNA-derived Pv200 proteins will now allow a full assessment of their utility in the diagnosis and immunoprophylaxis of the benign tertian malaria associated with P. vivax infection.
Approximately 460 base pairs (bp) of DNA sequence that included the second internal transcribed spacer (ITS2) and some flanking 5.8S and 28S ribosomal RNA coding regions were compared between the two closely related and morphologically indistinguishable mosquito species Anopheles freeborni and A. hermsi and a third related species, A. occidentalis. Sequences were determined from 14 clones of polymerase chain reaction (PCR)-amplified DNA obtained from four colonies of A. freeborni, two colonies of A. hermsi, and one individual A. occidentalis. Four clones showed independent single bp differences from the consensus for the relevant species. Eleven sites differed between the consensus sequences of A. hermsi and A. freeborni; 28 sites differed between A. hermsi and A. occidentalis. With the exception of a single bp mismatch in the 5.8S and two single bp mismatches near the undetermined junction of the ITS2 and 28S regions, all differences were confined to the ITS2 region. A PCR-based species-diagnostic assay for the cryptic species A. hermsi and A. freeborni was developed; it uses four synthetic oligonucleotides, two derived from areas of interspecies sequence difference in the ITS2, and two derived from highly conserved regions in the flanking coding sequences. Small amounts of mosquito DNA amplified in the presence of these four primers produce fragments of diagnostic size for each species: 900 bp for A. freeborni, 350 bp for A. hermsi, and approximately 1.2-1.4 kb for various other Anopheles species tested. We believe that this general approach to the development of species-diagnostic assays can be extended easily to other complexes of closely related, morphologically indistinguishable species.
Chelex treatment of Plasmodium falciparum and P. berghei infected tissues, in lieu of organic extraction, was followed directly by polymerase chain reaction amplification of primed circumsporozoite gene sequences. The amplified DNA products were detected in stained gels and hybridization blots of extracts from individual infected mosquitoes and dissected mosquito tissues as well as small volumes of infected blood. Parasite development, within the mosquito midgut and salivary gland, was also monitored as a function of time post infectious blood meal. The temporal presence of amplifiable circumsporozoite gene sequences in the infected mosquito midgut lumen, midgut endothelium, and salivary glands corresponded directly to the visual identification of ookinetes, oocysts, and salivary gland sporozoites, respectively.
Merozoite surface antigen 1 (MSA1) of several species of plasmodia has been shown to be a promising candidate for a vaccine directed against the asexual blood stages of malaria. We report the cloning and characterization of the MSA1 gene of the human malaria parasite Plasmodium vivax. This gene, which we call Pv200, encodes a polypeptide of 1726 amino acids and displays features described for MSA1 genes of other species, such as signal peptide and anchoring sequences, conserved cysteine residues, number of potential N-glycosylation sites, and repeats consisting here of 23 glutamine residues in a row. When the nucleotide and deduced amino acid sequences of the MSA1 of P. vivax are compared to those of another human malaria parasite, Plasmodium falciparum, and to those of the rodent parasite Plasmodium yoelii, 10 regions of high amino acid similarity are observed despite the very different dG + dC contents of the corresponding genes. All of the interspecies conserved regions reside within the conserved or semiconserved blocks delimited by the sequences of different alleles of the MSA1 gene of P. falciparum.
Phenotypic heterogeneity in the repetitive portion of a human malaria circumsporozoite (CS) protein, a major target of candidate vaccines, has been found. Over 14% of clinical cases of uncomplicated Plasmodium vivax malaria at two sites in western Thailand produced sporozoites immunologically distinct from previously characterized examples of the species. Monoclonal antibodies to the CS protein of other P. vivax isolates and to other species of human and simian malarias did not bind to these nonreactive sporozoites, nor did antibodies from monkeys immunized with a candidate vaccine made from the repeat portion of a New World CS protein. The section of the CS protein gene between the conserved regions I and II of a nonreactive isolate contained a nonapeptide repeat, Ala-Asn-Gly-Ala-Gly-Asn-Gln-Pro-Gly, identical at only three amino acid positions with published nonapeptide sequences. This heterogeneity implies that a P. vivax vaccine based on the CS protein repeat of one isolate will not be universally protective.
A high degree of polymorphism for the length and copy number of rDNA spacers, in both the X and Y chromosome clusters, has been found in a wild population of Drosophila melanogaster. The genetic behaviour of rDNA structural variants in separate and mixed populations derived from isofemale lines suggest that they are not subject to strong selection and are stable for over 1,000 generations. The high structural variability suggests an evolutionary rapid process of turnover in the family which could partly explain widespread sequence homogeneity (concerted evolution) of rDNA within a species.
Stable RNAs have regions of primary sequence that are nearly identical in every member of the Plasmodium genus and not found in the host or in other common pathogens. Several "genus-conserved" sequences, which flank hypervariable regions, were identified within the small subunit ribosomal RNA of Plasmodium species. Primers based on these conserved sequences permit amplification of species- or possibly even strain-specific sequences from samples of unknown composition. As an example of this approach, sequences from the four human malaria species were successfully recovered from Giemsa-stained blood smears, including two different sequences for Plasmodium ovale (of 91.5% similarity). This type of information is useful for epidemiological and phylogenetic analysis of any malaria species. We show that amplification of rRNA-derived sequences behaves in a competitive fashion during the cycles of polymerase amplification and therefore target sequences from Plasmodium species are amplified in proportion to their abundance in the sample. There are several implications of this finding. (1) The proportion of different products resulting from amplification from samples with mixed infections is closely related to the proportion of infecting species. (2) Direct quantitation of parasite nucleic acids within a sample can be derived when known amounts of competitor RNA are added to the RT/PCR reaction. (3) Amplification of rRNA sequences, using genus-specific primers, allows one to monitor the development of the parasite in the mosquito.
The merozoite surface protein MSP1, which is one of the most promising candidates for a malaria vaccine directed against erythrocytic stages, has been shown to be polymorphic in different malarial species. Characterization of the Plasmodium vivax MSP1 gene (Pv200) in two strains (Belem and Salvador-1) revealed the existence of several polymorphic regions. One of these regions has been examined here in primary parasite isolates obtained from patients in Sri Lanka. Oligonucleotide primers hybridizing to conserved parts of the gene on either side of a polymorphic region were used to amplify DNA from 22 isolates. Sequence analysis of the amplified portion of the MSP1 gene in five patients showed the existence of three types of polymorphic regions. Two were almost identical either to that of the Belem or to that of the Salvador-1 strain. The third polymorphic type appeared to have resulted from recombination between the two others. This recombination event took place inside a repeated part of the sequence.
The merozoite of Plasmodium vivax possesses a high molecular mass surface protein called Pv-merozoite surface protein 1, PvMSP-1, which exhibits antigenic diversity among isolates. In this study, the extent of sequence variation in the polymorphic region and the flanking interspecies conserved blocks (ICBs) 5 and 6 of the PvMSP-1 gene was analyzed using the polymerase chain reaction to amplify the DNA fragment encompassing these regions, followed by sequencing. Twenty different alleles were obtained from 15 Thai isolates. Results revealed five distinct sequence types of the polymorphic region, two of which were newly identified in this study: one probably generated by intragenic recombination at a site different from that previously reported and the other by duplication of a 30 nucleotide (nt) sequence at the 3' end of the region. On the other hand, almost all nucleotide substitutions in the flanking regions, ICB5 and ICB6, were dimorphic, creating microheterogeneity in the region. Furthermore, stretches of nucleotide substitutions were found to be linked in ICB6, suggesting the potential recombination sites between these stretches. It is also noted that extensive sequence variation in the PvMSP-1 gene and coinfection with different PvMSP-1 alleles occurred among the P. vivax population in the endemic areas of Thailand.
The sequences of the second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) were determined from seven palearctic mosquitoes species belonging to the Anopheles maculipennis species complex, namely An. atroparvus, An. labranchiae, An. maculipennis, An. messeae, An. melanoon, An. sacharovi and An. martinius. The length of the ITS2 ranged from 280 to 300 bp, with a GC content of 49.4-54.1%. With the exception of An. messeae, negligible levels of intraspecific polymorphism and no intrapopulation variation were observed. The phylogenetic relationships among the members of the maculipennis complex were inferred by maximum-parsimony analysis of the PAUP program and the neighbour-joining and maximum-likelihood analysis of the PHYLIP program. All of the trees obtained were almost identical in topology, although the relationships among three species, i.e. An. maculipennis, An. messeae and An. melanoon, remained unresolved. The phylogenies were in good agreement with the previous gene-enzyme and polytene chromosome banding pattern studies.
Malaria was once one of the most common diseases in Uzbekistan. There were massive epidemics with high mortality rates, wherein 140,000 to 700,000 cases of malaria were recorded. Following large-scale malaria control measures, the disease was eradicated in Uzbekistan in 1961 and the epidemiological situation is still favorable. The natural and climatic conditions that prevail in the Republic of Uzbekistan mean that the country is very susceptible to malaria. There are large water areas varying in type and origin, which provide a habitat for a number of epidemiologically dangerous species of malaria-transmitting mosquitoes in a single area. These are Anopheles maculipennis, An. pulcherrimus and An. superpictus. The prevailing temperatures promote rapid growth of vector mosquitoes and parasites and the malaria transmission season is over 5 months long. Seven malaria-transmitting mosquito species have been recently recorded in the Republic. DDT resistance has been so far noted in Anopheles maculipennis, An. hyrcanus and An. bifurcatus. An. superpictus is sensitive to all insecticides used in clinical practice (organophosphorus and organochlorine compounds, HOS, carbamates, pyrethroids). The most dangerous areas for transmitting malaria by importation are the flood plains of the country's main rivers, such as Syrdarya, Amudarya, Chirchik, Surkhana, etc., and rice-growing areas (an area of about 150,000 ha was under rice cultivation in 1999). The Republic is still very subjected to large-scale importations of malaria particularly in the towns and areas along the border with Tajikistan. There has been recently an increase in the incidence of infections imported into the Republic: 27 cases in 1995, 51 in 1996, 52 in 1997, 74 in 1998, and 78 in 1999. Eight regions of Uzbekistan border Tajikistan, their population is over 5.6 million people. In addition, close family ties between the populations of the frontier towns and regions further increase the risk for malaria to be imported and passed on. Noteworthy is the Surkhandaryin region that accounted for 60% of the cases recorded in 1999. The number of towns and villages where malaria occurs for the first time increased (49 and 46 cases in 1999 and 1998, respectively). The number of cases imported into rural areas also increased (70 (83%) cases in 1999 versus 48 (65%) cases in 1998); due to the large populations of malaria mosquitoes, there is a real danger that the disease may spread. In 1999, most cases of malaria were imported from Tajikistan (65 cases or 76% of all cases). There was a case from each of the following countries: Afghanistan, Pakistan, and Kazakhstan and 5 cases from Azerbaijan and Kyrgyzstan. The recorded cases included slighly more men than women (54% vs 46%). There were 10 infected children under 14 years, which was 23.5% of all notified cases. Analyzing various populations showed that 67.1% of the patients visited their relatives in malaria-endemic countries (mostly Tajikistan) and 25.8% migrated from Tajikistan. All the detected cases were confirmed by laboratory tests. As in the past, most cases were tertian (P. vivax) malaria (n = 82 or 96.4% of all cases). Tropical (P. falciparum) malaria was confirmed in 3 (3.5%) cases. These cases had been imported from Tajikistan into the Surkhandaryin region. Seventy seven (91%) cases were detected in the epidemical season. Of them 58 (68.2%) cases were detected during a malaria transmission season. Seven cases who contacted the patients with imported malaria and were infected were recorded in 1999. They included 4 and 3 cases in the Surkhandaryin and Kashkadaryin Regions, respectively. In 1999, there was a decline in the number of malaria patients who needed health care and in the diagnosed malaria cases in therapeutical and prophylactic institutions. Throughout the country, 34 (40%) of the 85 detected cases presented within 3 days of malaria outbreak (68.9% in 1998). Malaria was immediate diagnosed in 43.5% of cases (64.9% in 1998). The remaining cases were diagnosed as having acute respiratory viral infections, tropical and parasitic diseases, viral hepatitis, or influenza. Early diagnosis of malaria was made in 60% of cases (77% in 1998). Three cases of imported tertian malaria were recorded in the Tashkent Region in the first quarter of 2000. They were imported from Tajikistan into rural areas and the patients had been infected during the 1999 season. Epidemiological surveillance of malaria in Uzbekistan is regularly carried out by the general network of health facilities and by the departments of parasitology of state epidemiological surveillance centers in collaboration with medical administrative departments, the Ministry of Agriculture and Fisheries, the L.M. Isayev Research Institute of Medical Parasitology, and other agencies. Active links are maintained with WHO under the Roll Back Malaria programme. Great emphasis is laid on medical staff training at all levels. During the 1999 epidemiological survey, 672,536 laboratory tests were performed on blood samples from suspected malaria patients and individuals who had visited malaria-endemic countries, 55% of them suffering from fever. A total area of 17 million m2 of dwelling and nondwelling buildings 20 ha of water areas were treated against mosquitoes and the larvivorous fish Gambusia was put into the water areas occupying 6,500 ha. In all cases of malaria, the focus of infection was epidemiologically surveyed and required epidemic preventive measures were implemented. All malaria patients received a full course of radical therapy and recovered completely. The epidemiological surveillance system for malaria is affected by staff shortages at the parasitology departments of state epidemiological surveillance centers and by shortages of microscopes, reagents, sterilizing equipment, insecticides, etc. There are still difficulties in obtaining supplies of primaquine although a small stock is locally available as due to WHO humanitarian assistance. The Epidemiological Malaria Surveillance Programme for the Republic of Uzbekistan for 2000-2004, intended to strengthen the epidemic control capacity of health care facilities, Ministry of Health, is under adoption. The following activities are scheduled for 2000: to plan malaria control activities, including the zoning of the country by the risk of malaria transmission in accordance with republic-leveled directives, instructions, and methodology and WHO recommendations: adjustments to these plans to be made as necessary; to fill vacant posts in the parasitology departments of state epidemiological surveillance centers; to procure stocks of antimalarial drugs, reagents, insecticides, sterilizing equipment, etc., to be paid for from epidemiological service resources; to include malaria issues into certifying tests for physicians, as appropriate for the posts to be occupied and their level of qualifications; to publish posters, brochures, and leaflets about malaria prevention before the malaria transmission season for health education; to hold seminars and meetings for health workers on the etiology of malaria, its clinical features, diagnosis, treatment, and prevention.
Malaria due to Plasmodium vivax is globally widespread and is associated with substantial morbidity. The parasite was previously prevalent in temperate areas from which it has been eradicated, however there is a risk of re-introduction because of increased international travel and migration. Following the occurrence of an autochthonous case of P. vivax malaria in Italy after decades of malaria eradication, we applied a molecular approach to compare parasites involved in the introduced case and to determine whether a highly polymorphic gene marker could be useful to tag a P. vivax isolate geographically. To this end, the sequence encompassing the interspecies conserved blocks 5 and 6 of the gene encoding for merozoite surface protein 1 (msp-1) was determined in 16 P. vivax isolates from different regions, and analysed along with 24 pvmsp-1 sequences downloaded from published data. Results have shown that: (i). parasites from the introduced case and the putative source of infection identified following epidemiological investigation, although very similar, differed in three nucleotide substitutions, of which one non synonymous; ii). some geographical isolates looked tightly clustered (e.g. Korean and Punjab isolates), but others were less so.
Little is known of the genetic diversity and population structure of Plasmodium vivax, a debilitating and highly prevalent malaria parasite of humans. This article reviews the known polymorphic genetic markers, summarizes current data on the population structure of this parasite and discusses future prospects for using knowledge of the genetic diversity to improve control measures.
Vector bionomics in the epidemiology and control of malaria–—Part II. World Health Organization
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Molecular analysis of Plasmodium vivax relapses using the MSP1 molecule as a genetic marker Plasmodium: genus-conserved primers for species identification and quan-titation Analysis of Plasmodium vivax merozoite surface protein-1 gene sequences from resurgent Korean isolates
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The rate of turnover of structural variants in the ribosomal gene family of Drosophila melanogaster The genetic diversity of Plasmodium vivax populations Primary structure of the merozoite surface antigen 1 of Plasmodium vivax reveals sequences conserved between dif-ferent Plasmodium species
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Vector bionomics in the epidemiology and control of malaria-Part II. World Health Organization, Geneva, mimeographed document
- A R Zahar