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Lassa fever (LF) is a viral haemorrhagic fever endemic in West Africa and spread primarily by the multimammate rat, Mastomys natalensis . As there is no vaccine, reduction of rodent-human transmission is essential for disease control. As the household is thought to be a key site of transmission, understanding domestic risk factors for M. natalensis...
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... the 585 rooms, there were a total of 376 rodent captures over the 3,600 trapping nights, with at least one capture occurring in 234 (40.0%) rooms. A histogram showing the distribution of the number of rodent captures is shown in Fig. 1. Overall, the mean number of captures was 0.64 per room (95% CI 0.56-0.72, SD: 0.97), with a minimum of zero and a maximum of five. The variance of rodent abundance was 0.94, which was higher than the mean, indicating the data may be over dispersed. Village was also associated with rodent abundance, with Dalafilani having a lower rate ...
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Abstract: Benna is a new monospecific genus in the Melastomataceae, from the Benna Plateau in Forécariah Prefecture in Guinea, West Africa. Molecular sequence data show the genus Benna is nested within the tribe Sonerileae but clearly unrelated to the other African Sonerileae genera. The genus is weakly supported as sister to the South American Son...
Citations
... In an analysis focusing on environmental correlates, Clark et al. [14] applied negative binomial and poisson regression models to identify domestic factors associated with increased rodent abundance in regions of rural upper Guinea endemic for Lassa fever. Complementing this environmental perspective, Redding et al. [15] leveraged poisson regression to elucidate geographical and climatic determinants linked to the spatial distribution of confirmed Lassa fever cases in Nigeria. ...
... Clade 2gδ, on the other hand, is distributed into both Edo and Ondo states. In countries like Guinea, Lassa fever has long been regarded as a disease of the rural areas [24,38]. Our findings show that, at least within Nigeria, larger, relatively urban localities play an important part in the propagation of the virus. ...
We phylogenetically compared sequences of the zoonotic Lassa virus (LASV) obtained from Mastomys rodents in seven localities across the highly endemic Edo and Ondo States within Nigeria. Sequencing 1641 nt from the S segment of the virus genome, we resolved clades within lineage II that were either limited to Ebudin and Okhuesan in Edo state (2g-beta) or along Owo-Okeluse-Ifon in Ondo state (2g-gamma). We also found clades within Ekpoma, a relatively large cosmopolitan town in Edo state, that extended into other localities within Edo (2g-alpha) and Ondo (2g-delta). LASV variants from M. natalensis within Ebudin and Ekpoma in Edo State (dated approximately 1961) were more ancient compared to those from Ondo state (approximately 1977), suggesting a broadly east-west virus migration across south-western Nigeria; a pattern not always consistent with LASV sequences derived from humans in the same localities. Additionally, in Ebudin and Ekpoma, LASV sequences between M. natalensis and M. erythroleucus were interspersed on the phylogenetic tree, but those from M. erythroleucus were estimated to emerge more recently (approximately 2005). Overall, our results show that LASV amplification in certain localities (reaching a prevalence as high as 76% in Okeluse), anthropogenically-aided spread of rodent-borne variants amidst the larger towns (involving communal accommodation such as student hostels), and virus-exchange between syntopic M. natalensis and M. erythroleucus rodents (as the latter, a savanna species, encroaches southward into the degraded forest) pose perpetual zoonotic hazard across the Edo-Ondo Lassa fever belt, threatening to accelerate the dissemination of the virus into non endemic areas.
... [17,61] are needed to provide a better understanding of the avenues of human-rodent interaction in pregnancy to support development of effective control strategies. [17,[62][63][64] In the interim, advocating public health measures for rodent control such as proper sanitation and hygiene, improved housing and health education could support Lassa fever control efforts. [64,65]. ...
... [17,[62][63][64] In the interim, advocating public health measures for rodent control such as proper sanitation and hygiene, improved housing and health education could support Lassa fever control efforts. [64,65]. ...
Background:
There is limited epidemiological evidence on Lassa fever in pregnant women with acute gaps on prevalence, infection incidence, and risk factors. Such evidence would facilitate the design of therapeutic and vaccine trials and the design of control programs. Our study sought to address some of these gaps by estimating the seroprevalence and seroconversion risk of Lassa fever in pregnant women.
Methodology/principal findings:
We conducted a prospective hospital-based cohort between February and December 2019 in Edo State, Southern Nigeria, enrolling pregnant women at antenatal clinic and following them up at delivery. Samples were evaluated for IgG antibodies against Lassa virus. The study demonstrates a seroprevalence of Lassa IgG antibodies of 49.6% and a seroconversion risk of 20.8%. Seropositivity was strongly correlated with rodent exposure around homes with an attributable risk proportion of 35%. Seroreversion was also seen with a seroreversion risk of 13.4%.
Conclusions/significance:
Our study suggests that 50% of pregnant women were at risk of Lassa infection and that 35.0% of infections might be preventable by avoiding rodent exposure and conditions which facilitate infestation and the risk of human-rodent contact. While the evidence on rodent exposure is subjective and further studies are needed to provide a better understanding of the avenues of human-rodent interaction; public health measures to decrease the risk of rodent infestation and the risk of spill over events may be beneficial. With an estimated seroconversion risk of 20.8%, our study suggests an appreciable risk of contracting Lassa fever during pregnancy and while most of these seroconversions may not be new infections, given the high risk of adverse outcomes in pregnancy, it supports the need for preventative and therapeutic options against Lassa fever in pregnancy. The occurrence of seroreversion in our study suggests that the prevalence obtained in this, and other cohorts may be an underestimate of the actual proportion of women of childbearing age who present at pregnancy with prior LASV exposure. Additionally, the occurrence of both seroconversion and seroreversion in this cohort suggests that these parameters would need to be considered for the development of Lassa vaccine efficacy, effectiveness, and utility models.
... Most importantly, respondents mentioned high numbers of rodents within houses and granaries during dry seasons as resources outside become scarce. This was confirmed in Guinea by Fichet-Calvet et al. (2007) who reported Lassa fever cases all year round, and by Clark et al. (2021) who cite household contact with rodents in households during the dry season as the main factors that sustain Lassa virus transmission between rodents and humans. ...
This socio-anthropological study investigates the relations between humans and rodents in an area adjacent to the Limpopo National Park in Mozambique. Designed as part of the larger researcher on mammarenaviruses, it explores the social dimensions of the rodent-human interface, considering its spatial and temporal variability. Its results contribute to our understanding of the socio-ecological context in which new pathogens or new routes of pathogen transmission could arise and potentially spread diseases. A vulnerability-based approach was used to assess human exposure, sensibility and capacity to adapt to rodents. This study revealed: (i) Local knowledge of the dynamic of rodent populations over the last few decades, with new invasive rodents displacing native species; (ii) the social-ecological factors thought to be behind this invasion: climate change, new infrastructure (e.g., construction of a dam), new agricultural practices (e.g., cultivation of sunflowers) and policies (human resettlement); (iii) the significant impact associated with new invasive rodents (e.g., crop losses, damage to belongings), the limited capacity for individual and collective interventions to mitigate damage, and the little concern shown for rodent-related diseases; (iv) women and girls’ high vulnerability to potential rodent-borne diseases due to frequent direct and indirect contact with rodents in the domestic space; and (v) the added-value of using a vulnerability-based methodology, over the more commonly used Knowledge-Attitudes-Practices (KAP) methodology, to map the structural factors shaping the human-rodent interface and its dynamic. Our findings suggest that the vulnerability-based approach could offer an opportunity to better respond to the One Health ambition by integrating social dimensions of health and grasping the complexity of the social and material context in which new pathogens could emerge and spread.
One Health Statement
The present socio-anthropological study of the human-rodent interface comes in complement to a previous eco-epidemiological survey focusing on the rodent-virus interface. It explores the cultural and social dimensions of the interactions between rodent-human, considering spatial and temporal variability. In doing so, it contributes to the understanding of the socio-ecological dynamic, in which new viral transmission can occur and disease spread. It exemplifies, based on local knowledge, how socio-ecological changes can create new routes for the emerging virus and highlights the vulnerability of the exposed human population to address the potential related health risks. This multidisciplinary and dynamic approach of how humans and rodents interact, and how these interactions are shaped by their changing environment is a contribution to a systemic approach to health, in line with the One health paradigm.
... Globally, West Africa is the Epicenter of Lassa fever [26] (Figure 2). In West Africa, about 100,000 to 300,000 new cases of Lassa fever have been reported with a mortality rate of 5,000 persons per annum [24,29,53,54]. In Nigeria, Lassa fever has occurred in several states across the six geopolitical zones and the Annual epidemics of Lassa fever recur throughout Nigeria's many states, causing different degrees and rates of illness and death respectively [56]. ...
With the advent of COVID-19, infectious diseases are increasingly a cause of concern to both national and international governments as well as non-governmental organizations. This review focuses on Lassa fever incidence, prevalence, and socioecological factors
influencing the spread and management of the disease in Nigeria using data mined from the Nigeria Centre for Disease Control and other public databases. Lassa fever and the
causative agent Lassa virus (LASV) and vector, Mastomys natalensis is becoming a topical issue despite the neglected tropical disease status. The primary transmission mode of LASV has not been fully comprehended but several social and environmental factors have been implicated to either play a major role in determining the rate of transmission or exacerbating transmission risks. Nonetheless, some transmission route includes faeco-oral, rodent bites, and the consumption of rodent meat. From epidemiolocal studies and surveillance, it is glaring that LASV is a West African
phenomenon. In West Africa, about 100,000 to 300,000 new cases of Lassa fever have been reported with a mortality rate of 5,000 persons per year. In Nigeria, Lassa fever
has occurred in several states across the six geopolitical zones and the federal capital territory. However, Edo State in the Southsouth geopolitical zone and Ondo State in the
Southwest geopolitical zone is the core epicentre of the virus since December 2016 in Nigeria. Some environmental conditions that contribute to exacerbating the incidence of
Lassa fever include weak environmental hygiene laws, poor housing, and regional planning, indiscriminate disposal of wastes, poor food handling, and storage, absence of a law against eating Mastomys natalensis, deforestation, and poor agricultural practices as well as climate change.
