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The egg morphology of minute intestinal flukes (MIF) that can occur as human infections in the Republic of Korea, i.e., Metagonimus yokogawai, M. miyatai, M. takahashii, Heterophyes nocens, Heterophyopsis continua, Stellantchasmus falcatus, Stictodora fuscata, Pygidiopsis summa, and Gymnophalloides seoi, was studied in comparison with Clonorchis si...
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Citations
... The distinguishing features of OV eggs include their tiny size, oval shape, and presence of an operculum and opercular knob. However, despite being smaller and oval in shape, MIF eggs lack an opercular knob [3]. Therefore, prevention control include, regular screening, and treatment programs are Katz method, feces and egg shells are cleared by glycerol. ...
Background:
The Kato-Katz method is a commonly used diagnostic tool for helminth infections, particularly in field studies. This method can yield inaccurate results when samples contain eggs that are similar in appearance, such as Minute Intestinal Fluke (MIF) and Opisthorchis viverrini (OV) eggs. The close resemblance of eggs can be problematic and raises the possibility of false diagnoses. The objectives were to compare the diagnostic performance of the Kato-Katz method for accurately identifying MIF and OV and to provide evidence of possible misclassification. Methods: Based on questionnaire responses from 15 (young parasitologists and public health staff), the test comprised 50 MIF egg images and 50 OV egg images, for a total of 100 Google Form questionnaires.
Results:
The morphology of MIF and OV eggs found size and shape similarity and found that the shoulder rims were small, while the OV egg found the knobs had disappeared. The opercular conjunction was apparent, the shoulder rims and miricidium were prominent. The average percentage of correctly classified infections was 61.6 ± 12.1%. The accuracy percentages for both public health staff and young parasitologists in identifying were found to be 59.0 ± 14.8 and 66.8 ± 2.8, respectively. There was no significant difference observed in both groups.
Conclusion:
These findings highlight the need for improving the accuracy of parasite identification. Preserving stool samples before the Kato-Katz method can help mitigate the potential degradation or distortion of parasite eggs. The incorrect classification of both eggs had an impact on treatment plans and the policy of parasite control programs.
... However, an abopercular knob is not seen in E. pancreaticum eggs. In comparison to other minute intestinal fluke eggs, there are thread-like ridges on the eggshell surface of Pygiodiopsis summa, multiple minute ridges on Metagonimus yokogawai eggshells, rough eggshells on Heterophyopsis continua, and a muskmelon-like surface on C. sinensis (Lee et al. 2012). A distinct melon pattern is also exhibited on eggshell surface of O. viverrini that is thought to play a vital role in attachment of the eggs to aquatic plants to reach their first intermediate host (Apinhasmit et al. 1994). ...
... philippinensis and T. trichiura) (Fischer et al., 2018) and asymmetric-shaped (E. vermicularis) eggs (Camacho and Reinhard, 2019), were similar to a cluster of fluke eggs (Fasciola spp., Paragonimus spp., and Opisthorchis spp.), which are ovoid and pyriform in shape (Lee et al., 2012). While a cluster of cestode and S. mekongi eggs was separated from the other two clusters. ...
Copro-microscopic diagnostic methods are the most common approach for screening patients with parasitic infections. However, expertise is required to identify helminthic eggs from fecal specimens. Consequently, new methods are required. Novel technologies have recently been developed for the classification of organisms, including geometric morphometric (GM) approaches. In this study, the outline-based GM approach was used to distinguish the eggs of 12 common human parasite species, including Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, hookworm, Capillaria philippinensis, Opisthorchis spp., Fasciola spp., Paragonimus spp., Schistosoma mekongi, Taenia spp., Hymenolepis diminuta and Hymenolepis nana. The GM analysis revealed that the size cannot be used as the main variable in the identification of parasite species at the egg stage, producing only 30.18% overall accuracy. However, comparisons of shape based on the Mahalanobis distances between pairs of parasite species showed significant differences in all pairs (p < 0.05). The shape analysis produced 84.29% overall accuracy. This is the first time that outline-based GM has been preliminarily confirmed as a valuable approach to support copro-microscopic analysis, in order to effectively screen helminth eggs. However, further studies with a larger set of helminth eggs and artefacts should be carried out to increase confidence in the identification of parasite species in the absence of local experts.
... Measurements on the SEM image revealed shorter lengths, but this is most likely the case because the bases of the spines are deeply embedded in the tegument covering parts of the entire surface. The SEM image of Prosthogonimus eggs showed a net-like structure on the shell similar to other small trematode eggs (Shin et al., 2009;Lee et al., 2012). Eggs in the distal uterus in our material measured only 23 × 14 μm, closest to the eggs from P. cuneatus (26 × 14 μm), and they were considerably smaller than those of other species. ...
At a routine health check of a female peregrine falcon, 23 trematodes preliminary identified as Prosthogonimus sp. were removed from the bursa of Fabricius. Based on morphological and molecular examination, a new species, Prosthogonimus falconis , was described. The pear-shaped flukes were 4.3–6.9 mm long, with greatest width posterior to testes. Tegumental spines measuring between 17 and 21 μm long covered the whole body. Length and width ratio of oral to ventral suckers were 1:1.3. Extracaecal, multifollicular vitelline glands commenced prior to acetabulum and terminated posterior to testes. Eggs in the distal uterus measured 21 × 12 μm. Molecular analysis of internal transcribed spacer 2, cytochrome c oxidase subunit 1 and NADH dehydrogenase subunit 1 gene regions revealed that the new species described here is phylogenetically closest to Prosthogonimus cuneatus and Prosthogonimus pellucidus clusters.
... Another difficulty entailed with the diagnosis of the gymnophalloidiasis is the identification of the eggs. They are very small (approximately 23 × 13 μm) and thin and transparent shelled (Fig. 7.6c) (Lee et al. 2012). Due to their small size, the eggs can be overlooked by an inexpert analyst or misdiagnosed as a bubble or other artifacts. ...
... Due to their small size, the eggs can be overlooked by an inexpert analyst or misdiagnosed as a bubble or other artifacts. Moreover, differential diagnosis with other digeneans may be difficult (Lee et al. 2012). ...
... The specific diagnosis may require the recovery of adult worms after treatment and purgation ). Because of this fact, close examination of the egg sizes may be of help (Lee et al. 2012). Moreover, light infections can be easily missed since the egg laying capacity of the heterophyids is low (Sripa et al. 2010). ...
Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse with regard to their morphology, geographical distribution, and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host–parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment, and control.
... Nevertheless, the "shoulders" of eggs have been used for differentiation, as they are usually not as prominent in O. viverrini, and heterophyid eggs usually have an inconspicuous operculum flush with its shell surface. The surface ultrastructure of eggs by scanning electron microscopy in Korea revealed that C. sinensis eggs are covered with prominent and elevated ridges called "muskmelon-like structures," which were not observed in some heterophyid (i.e., Metagonimus, Heterophyes, Stellantchasmus, Stictodora, Pygidiopsis) and gymnophallid (Gymnophalloides) eggs (Lee et al. 2012a). ...
... From an exclusively diagnostic point of view, species presenting large eggs (>50 μm) and others, the vast majority, presenting small eggs (<50 μm) are included in this group. Although accurate species identification is often difficult as the eggs of most of these flukes are similar in size and morphology, the most problematic distinction occurs within the group producing small eggs, called "minor intestinal flukes" (MIF) by some authors (Lee et al. 1984(Lee et al. , 2012aKaewkes et al. 1991;Chai 2007Chai , 2009); an abbreviation apparently rather inadequate as it coincides with a fecal preservative (merthiolate iodine formaldehyde-MIF) used in stool examinations. The term "tiny intestinal flukes" (TIF) is occasionally used as well (Ash and Orihel 2007). ...
... yokogawai 26-28 × 15-17 μm, H. heterophyes 28-30 × 15-17 μm, and H. taichui 20-30 × 14-17 μm) (Ditrich et al. 1992;Sukontason et al. 1999;Ash and Orihel 2007). However, establishing a specific differentiation is very complicated, even at genus level, within this helminth group due to their similar morphology, and their reduced egg size (Lee et al. 1984(Lee et al. , 2012aTesana et al. 1991;Ditrich et al. 1992;Sukontason et al. 1999;Chai et al. 2015). Therefore, the term "heterophyid fluke infection" is recommended in their diagnosis (Chai and Lee 2002). ...
Digenetic trematodes form a major group of human parasites, affecting a large number of humans, especially in endemic foci. Over 100 species have been reported infecting humans, including blood, lung, liver, and intestinal parasites. Traditionally, trematode infections have been diagnosed by parasitological methods based on the detection and the identification of eggs in different clinical samples. However, this is complicated due to the morphological similarity between eggs of different trematode species and other factors such as lack of sensitivity or ectopic locations of the parasites. Moreover, the problem is currently aggravated by migratory flows, international travel, international trade of foods, and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In this chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.
... Demonstration of liver-fluke eggs and/or specific DNA fragments in stool or bile samples are definitive diagnostic signs. However, differential diagnosis of liver-fluke eggs from those of other minute intestinal flukes is difficult even for experts [10]. Patients may refuse to submit faecal samples. ...
... However, to date, endemicity of opisthorchiasis and clonorchiasis do not geographically overlap with each other [1,2,4]. Differential diagnosis of small liver-fluke infections from other intestinal trematodiases might be more important because some of these parasites expel eggs that are morphologically indistinguishable from those of liver-flukes [10,28]. Clinically, such intestinal trematodiases are usually transient but are not associated with serious illness. ...
Objectives:
To determine the potential for immunodiagnostic application of two recombinant forms of Clonorchis sinensis omega-class glutathione transferases (rCsGSTo1 and rCsGSTo2) against human small liver-fluke C. sinensis and Opisthorchis viverrini infections.
Methods:
Specific antibody levels against rCsGSTo1 and rCsGSTo2 in patients' sera of egg-positive opisthorchiasis (n = 87) and clonorchiasis (n = 120), as well as those in sera from patients with other helminthic infections (n = 252) and healthy controls (n = 40) were retrospectively analyzed by enzyme-linked immunosorbent assay (ELISA).
Results:
We observed highly positive correlation coefficients between specific antibody levels against rCsGSTo1 and rCsGSTo2 and egg counts per gram of feces (EPG) of patients with opisthorchiasis (n = 87; r = 0.88 for rCsGSTo1 and r = 0.90 for rCsGSTo2). Sera from opisthorchiasis patients whose EPG counts >100 (n = 43) revealed high antibody titers against both antigens. Patients' sera with low EPG counts (<100, n = 44) also exhibited reliable sensitivities of 93.2% and 97.7% for rCsGSTo1 and rCsGSTo2, respectively. Sera from clonorchiasis patients showed sensitivities of 90% (108/120 samples) and 89.2% (107/120 sera) for rCsGSTo1 and rCsGSTo2. Overall diagnostic sensitivities for liver-fluke infections were 92.3% for rCsGSTo1 (191/207 samples) and 93.2% for rCsGSTo2 (193/207 samples). Specificities were 89.7% (rCsGSTo1) and 97.6% (rCsGSTo2).
Conclusions:
Detection of specific antibody levels against rCsGSTo1 or rCsGSTo2 might be promising for the serodiagnosis of patients infected with these two phylogenetically-close carcinogenic liver-flukes.
... An important drawback in the diagnosis of Metagonimus spp., Heterophyes spp., and Haplorchis spp. and other heterophyid infection is close similarity of their eggs to other heterophyid species as well as small liver flukes (Clonorchis sinensis, Opisthorchis viverrini, and Opisthorchis felineus) and lecithodendriid flukes (Prosthodendrium molenkampi and Phaneropsolus bonnei) Lee et al., 2012;Chai, 2015). Therefore, in areas of mixed infections, specific diagnosis is usually difficult unless the adult flukes are recovered (Chai, 2007). ...
... The specific diagnosis of human P. summa or S. falcatus infection is problematic because it is difficult to discriminate these eggs from other heterophyid or opisthorchiid eggs in fecal examinations Lee JJ et al., 2012). However, a favorable point is that P. summa eggs are very small in size and S. falcatus eggs are slightly elongated Chai et al., 2004;Lee JJ et al., 2012). ...
... The specific diagnosis of human P. summa or S. falcatus infection is problematic because it is difficult to discriminate these eggs from other heterophyid or opisthorchiid eggs in fecal examinations Lee JJ et al., 2012). However, a favorable point is that P. summa eggs are very small in size and S. falcatus eggs are slightly elongated Chai et al., 2004;Lee JJ et al., 2012). The small egg size is also applicable to P. genata infection in Egypt (Youssef et al., 1987a). ...
Fishborne heterophyid trematodes infecting humans are at least 29 species worldwide and belong to 13 genera. Its global burden is much more than 7 million infected people. They include Metagonimus (M. yokogawai, M. takahashii, M. miyatai, M. minutus, and M. katsuradai), Heterophyes (H. heterophyes, H. nocens, H. dispar, and H. aequalis), Haplorchis (H. taichui, H. pumilio, H. yokogawai, and H. vanissimus), Pygidiopsis (P. summa and P. genata), Heterophyopsis (H. continua), Stellantchasmus (S. falcatus), Centrocestus (C. formosanus, C. armatus, C. cuspidatus, and C. kurokawai), Stictodora (S. fuscata and S. lari), Procerovum (P. varium and P. calderoni), Acanthotrema (A. felis), Apophallus (A. donicus), Ascocotyle (A. longa), and Cryptocotyle (C. lingua). Human infections are scattered around the world but the major endemic areas are located in Southeast Asia. The source of human infection is ingestion of raw or improperly cooked fish. The pathogenicity, host-parasite relationships, and clinical manifestations in each species infection are poorly understood; these should be elucidated particularly in immunocompromised hosts. Problems exist in the differential diagnosis of these parasitic infections because of close morphological similarity of eggs in feces and unavailability of alternative methods such as serology. Molecular diagnostic techniques are promising but they are still at an infant stage. Praziquantel has been proved to be highly effective against most of the patients infected with heterophyid flukes. Epidemiological surveys and detection of human infections are required for better understanding of the geographical distribution and global burden of each heterophyid species. In this review, the most updated knowledge on the morphology, biology, epidemiology, pathogenesis and pathology, immunology, clinical manifestations, diagnosis and treatment, and prevention and control of fishborne zoonotic heterophyid infections is provided.
... 21 In addition, liver fluke and other intestinal flukes infections can be superimposed and their eggs (Opisthorchis-like eggs) could be difficult to be microscopically differentiated. [22][23][24] The polymerase chain reaction (PCR)-based method for detection of liver fluke's genetic materials in stool could diagnose opisthorchiasis in 28.6% to 76.6% of cases in which stool microscopic examinations were negative. [25][26][27] Moreover, PCR-based method could be used to differentiate O. viverrini from other Opisthorchis-like eggs. ...
Cholangiocarcinoma (CCA) is an aggressive cancer arising from epithelial cells of the bile duct. Most patients with CCA have an unresectable tumor at the time of diagnosis. In Western countries, the risk of CCA increases in patients with primary sclerosing cholangitis, whereas liver fluke infection appears to be the major risk factor for CCA in Asian countries. A diagnosis of liver fluke infection often relies on stool samples, including microscopic examination, polymerase chain reaction-based assays, and fluke antigen detection. Tests of serum, saliva and urine samples are also potentially diagnostic. The presence of liver fluke along with exogenous carcinogens magnifies the risk of CCA in people living in endemic areas. The "liver fluke-cholangiocarcinoma" carcinogenesis pathways consist of mechanical damage to the bile duct epithelium, immunopathologic and cellular reactions to the liver fluke's antigens and excretory/secretory products, liver fluke-induced changes in the biliary tract microbiome and the effects of repeated treatment for liver fluke. A vaccine and novel biomarkers are needed for the primary and secondary prevention of CCA in endemic areas. Importantly, climate change exerts an effect on vector-borne parasitic diseases, and awareness of liver fluke should be enhanced in potentially migrated habitat areas.
... Digenetic trematodes, particularly intestinal and liver flukes, are widely distributed in many Asian countries including Korea, Vietnam, Myanmar, Cambodia, Laos and Thailand, and remain a public health problem throughout the region [1][2][3][4][5][6][7]. The heterophyid trematode and some liver flukes can infect mammals and humans who eat raw or uncooked infected-fish species such as Haplorchis taichui (H. ...
... Freshwater snails and fish typically serve as the intermediate host in most instances [1,6,14,15]. These trematodes are endemic throughout the Southeast Asian region, including Thailand, Lao PDR, Vietnam, Korea and the Philippines [1,2,5,7,10,15], with a high incidence of mixed infections involving small liver trematodes and other minute intestinal trematodes [16,17]. The distribution of trematodes requires specific suitable ecological conditions, typically involving certain water resources such as those located in agricultural areas as well as rivers and irrigation canals. ...
... Two species of heterophyid trematodes have been identified in this study, namely, H. taichui and H. pumilio, which are known to infect humans and other mammals, and are widely distributed in many provinces of Thailand such as Chiang Mai, Phitsanulok, Mae Hong Son, Kamphaeng Phet, and Tak [10,23,30], as well as in other close countries, like Lao PDR, Korea and Vietnam [2,5,7,16]. A recent study conducted in Lao PDR revealed that many patients were infected with H. taichui, with a 99.8% of the trematode specimens identified in patients [2]. ...
Objective: To analyze the prevalence of trematode infections in the snails intermediate host
Tarebia granifera and Melanoides tuberculata collected from Ratchaburi Province by a
molecular approach in order to construct a dendrogram to identify species at the cercarial stage.
Methods: Specimens were collected from nine districts located in Ratchaburi Province using
the stratified sampling method. The samples were examined for cercarial infection using the
crushing method. All specimens were amplified by region of internal transcribed spacer 2 (ITS2)
based on the PCR technique, and the sequence data were aligned in order to construct the
dendrogram by maximum likelihood with 10 000 bootstrap replicates.
Results: Five cercarial types were observed comprising parapleurolophocercous cercaria,
xiphidiocercaria, megarulous cercaria, furcocercous cercaria and transversotrema cercaria.
The overall prevalence of cercarial infection was found to be 7.92% (63 / 795). The
parapleurolophocercous cercaria was found in the highest level of prevalence followed by
xiphidiocercaria, megarulous cercaria, furcocercous cercaria and transversotrema cercaria,
respectively. The parapleurolophocercous cercaria samples were identified and separated
into Haplorchis taichui and Haplorchis pumilio, while xiphidiocercaria were identified as
Lecithodendriidae and megarulous cercaria were identified as Philophthalmus. The dendrogram
separated the cercariae into five groups, which were comprised of parapleurolophocercous
cercaria, xiphidiocercaria, megarulous cercaria, furcocercous cercaria and transversotrema
cercaria using the sequence of Angiostrongylus cantonensis as an out-group.
Conclusions: This is the first study to report on the prevalence of cercarial infection in
Ratchaburi Province, Thailand. The high prevalence of cercariae was revealed by the infection
in Tarebia granifera and Melanoides tuberculata. Thus, the sequence data of ITS2 can be used
to investigate the dendrogram of trematodes and can help to separate the collected samples at
the species level. This information can be used to create the prevention program for parasite
infection from intermediate hosts in the future.
