Helminth Eggs Detected in Soil Samples of a Possible Toilet Structure Found at the Capital Area of Ancient Baekje Kingdom of Korea

Although research conducted in East Asia has uncovered parasite eggs from ancient toilets or cesspits, data accumulated to date needs to be supplemented by more archaeoparasitological studies. We examined a total of 21 soil samples from a toilet-like structure at the Hwajisan site, a Baekje-period royal villa, in present-day Korea. At least 4 species of helminth eggs, i.e., Trichuris trichiura, Ascaris lumbricoides, Clonorchis sinensis, and Trichuris sp. (or Trichuris vulpis) were detected in 3 sediment samples of the structure that was likely a toilet used by Baekje nobles. The eggs of T. trichiura were found in all 3 samples (no. 1, 4, and 5); and A. lumbricoides eggs were detected in 2 samples (no. 4 and 5). C. sinensis and T. vulpis-like eggs were found in no. 5 sample. From the findings of this study, we can suppose that the soil-transmitted helminths were prevalent in ancient Korean people, including the nobles of Baekje Kingdom during the 5th to 7th century.     

V-shaped Pits in Regions of Ancient Baekje Kingdom Paleoparasitologically Confirmed as Likely Human-Waste Reservoirs

In a paleo-parasitological analysis of soil samples obtained from V-shaped pits dating to the ancient Baekje period in Korean history, we discovered Ascaris lumbricoides, Trichuris trichiura, and Clonorchis sinensis eggs. In light of the samples'' seriously contaminated state, the V-shaped pits might have served as toilets, cesspits, or dung heaps. For a long period of time, researchers scouring archaeological sites in Korea have had difficulties locating such structures. In this context then, the present report is unique because similar kind of the ancient ruins must become an ideal resource for successful sampling in our forthcoming paleoparasitological studies.     

Prevalence of Zoonotic Trematode Metacercariae in Freshwater Fish from Gangwon-do,Korea

The infection status of zoonotic trematode metacercariae was investigated in a total of 2,293 freshwater fish collected from 11 rivers or streams in 9 administrative regions of Gangwon-do, Korea for 5 years (2009-2013). All fish were collected by netting methods and examined using the artificial digestion methods. Clonorchis sinensis metacercariae were detected in 4 fish species, i.e., Pungtungia herzi, Squalidus japonicus coreanus, Acheilognathus rhombeus, and Ladislabia taczanowskii, from only Hantangang in Cheorwon-gun. Metagonimus spp. metacercariae were found in 1,154 (50.3%) fish and their average number per infected fish was 55.8. Among the positive fish species, especially Tribolodon hakonensis from Namdaecheon in Yangyang-gun and Plecoglossus altivelis from Osipcheon in Samcheok-si were most heavily infected. Centrocestus armatus metacercariae were detected in 611 (26.7%) fish and the average metacercarial burden per infected fish was 1,032. Two chub species, Zacco platypus and Zacco temminckii were highly and heavily infected with C. armatus metacercariae in almost all regions surveyed. Echinostoma spp. metacercariae were also found in 24 fish from a few localities, but their numbers per fish infected were very low. From the above results, it is confirmed that the metacercariae of intestinal flukes, especially Metagonimus spp. and C. armatus, were heavily infected, while C. sinensis metacercariae were rarely found in fish from Gangwon-do, Korea.     

Trichuris trichiura Infection Diagnosed by Colonoscopy: Case Reports and Review of Literature

Trichuris trichiura, commonly referred to as a whipworm, has a worldwide distribution, particularly among countries with warm, humid climates. In Korea, trichuriasis was a highly prevalent soil-transmitted helminthiasis until the 1970s. However, the nationwide prevalence decreased to 0.02% in 2004 as a result of national control activities and improvement in the socioeconomic status of Koreans. Most infected individuals have no distinct symptoms, if lightly infected. The diagnosis is typically confirmed by detection of T. trichiura eggs on examination of a stool sample; few reports have described detection of the parasite during colonoscopy. Recently, we managed 4 patients with trichuriasis who were diagnosed by detection of the parasite on colonoscopy, and we reviewed the literature on the colonoscopic diagnosis of T. trichiura in Korea. We suggest that colonoscopy might be a useful diagnostic tool, especially when infected by only a few male worms with no eggs in the stool.     

Cluster of Parasite Infections by the Spatial Scan Analysis in Korea

This study was performed to find out the clusters with high parasite infection risk to discuss the geographical pattern. Clusters were detected using SatScan software, which is a statistical spatial scan program using Kulldorff’s scan statistic. Information on the parasitic infection cases in Korea 2011–2019 were collected from the Korea Centers for Disease Control and Prevention. Clusters of Ascaris lumbricoides infection were detected in Jeollabuk-do, and T. trichiura in Ulsan, Busan, and Gyeongsangnam-do. C. sinensis clusters were detected in Ulsan, Daegu, Busan, Gyeongsangnam-do, and Gyeongsangbuk-do. Clusters of intestinal trematodes were detected in Ulsan, Busan, and Gyeongsangnam-do. P. westermani cluster was found in Jeollabuk-do. E. vermicularis clusters were distributed in Gangwon-do, Jeju-do, Daegu, Daejeon, and Gwangju. This clustering information can be referred for surveillance and control on the parasitic infection outbreak in the infection-prone areas.     

Estimating the sensitivity and specificity of Kato-Katz stool examination technique for detection of hookworms, Ascaris lumbricoides and Trichuris trichiura infections in humans in the absence of a ‘gold standard’

The accuracy of the Kato-Katz technique in identifying individuals with soil-transmitted helminth (STH) infections is limited by day-to-day variation in helminth egg excretion, confusion with other parasites and the laboratory technicians’ experience. We aimed to estimate the sensitivity and specificity of the Kato-Katz technique to detect infection with Ascaris lumbricoides, hookworm and Trichuris trichiura using a Bayesian approach in the absence of a ‘gold standard’. Data were obtained from a longitudinal study conducted between January 2004 and December 2005 in Samar Province, the Philippines. Each participant provided between one and three stool samples over consecutive days. Stool samples were examined using the Kato-Katz technique and reported as positive or negative for STHs. In the presence of measurement error, the true status of each individual is considered as latent data. Using a Bayesian method, we calculated marginal posterior densities of sensitivity and specificity parameters from the product of the likelihood function of observed and latent data. A uniform prior distribution was used (beta distribution: α = 1, β = 1). A total of 5624 individuals provided at least one stool sample. One, two and three stool samples were provided by 1582, 1893 and 2149 individuals, respectively. All STHs showed variation in test results from day to day. Sensitivity estimates of the Kato-Katz technique for one stool sample were 96.9% (95% Bayesian Credible Interval [BCI]: 96.1%, 97.6%), 65.2% (60.0%, 69.8%) and 91.4% (90.5%, 92.3%), for A. lumbricoides, hookworm and T. trichiura, respectively. Specificity estimates for one stool sample were 96.1% (95.5%, 96.7%), 93.8% (92.4%, 95.4%) and 94.4% (93.2%, 95.5%), for A. lumbricoides, hookworm and T. trichiura, respectively. Our results show that the Kato-Katz technique can perform with reasonable accuracy with one day’s stool collection for A. lumbricoides and T. trichiura. Low sensitivity of the Kato-Katz for detection of hookworm infection may be related to rapid degeneration of delicate hookworm eggs with time.     

Intestinal Helminthic Infections Diagnosed by Colonoscopy in a Regional Hospital during 2001-2008

The present study investigated characteristics of 24 parasite infection cases detected during colonoscopy in a regional hospital from January 2001 to December 2008. Sixteen patients were confirmed with Trichuris trichiura infection, 6 patients were with Ascaris lumbricoides infection, 1 patient with Enterobius vermicularis infection, and 1 patient with Anisakis infection. Among them, 7 patients (43.8%) were asymptomatic. Colonoscopy findings were normal in 18 patients (75.0%). Among the patients with T. trichiura infection, colonoscopy showed several erosions in 2 patients (8.3%) and non-specific inflammation of the affected segment of the colon in 3 patients (12.5%). In 1 patient with anisakiasis, colonoscopy revealed a markedly swollen colonic wall. Stool examinations were performed before treatment in 7 patients (29.2%) and were all negative for parasite eggs or worms. These results suggest that colonoscopy is a useful diagnostic approach for parasitic infections even for asymptomatic patients and for patients with negative stool examinations.     

High Endemicity with Clonorchis sinensis Metacercariae in Fish from Yongjeon-cheon (Stream) in Cheongsong-gun,Gyeongsangbuk-do,Korea

The infection status with Clonorchis sinensis metacercariae (CsMc) was examined in freshwater fishes from Yongjeon-cheon (a branch of Nakdong-gang) located in Cheongsong-gun, Gyeongsangbuk-do, the Republic of Korea (Korea). A total of 750 fishes in 19 species were examined by the artificial digestion method for 2 years (2019 and 2020). CsMc were detected in 378 (51.4%) out of 735 fishes in 14 species (73.7%), and the infection intensity was 666 per fish infected. In 2019, CsMc were found in 172 (68.0%) out of 253 fishes in 10 species, and the infection intensity was 565 per fish infected. In 2020, CsMc were detected in 206 (62.2%) out of 331 fishes in 10 species, and the infection intensity was 751 per fish infected. The other zoonotic trematode, ie. Metagonimus spp., Centrocestus armatus, Echinostoma spp. and Clinostomum complanatum, metacercariae were also detected in fishes from the survey streams, but their endemicities were relatively low. Conclusively, it was first confirmed that CsMc are highly endemic in fishes from Yongjeon-cheon in Cheongsong-gun, Gyeongsangbuk-do, Korea.     

Efficacy and side effects of albendazole currently in use against Ascaris,Trichuris and hookworm among school children in Wondo Genet,southern Ethiopia

Monitoring the efficacy of anthelminthic drugs is essential. The objective of this study was to assess the efficacy of a single oral dose of 400 mg albendazole (ABZ) against the major soil-transmitted helminth (STH) infection in school children, Wondo Genet, southern Ethiopia. A single fresh stool sample was collected from 298 school children and examined using a duplicate smear of the Kato–Katz method. Children positive for STH infections were treated with single oral dose of 400 mg ABZ and re-examined for intestinal helminth infections 21 days post-treatment. The participants were interviewed for symptoms related with the drug uptake 24 h after ABZ treatment. Children positive for Schistosoma mansoni infections were treated with Praziquantel (40 mg/kg of body weight) after an ABZ treatment follow up survey. 51.3%, 49.7%, 44.6% and 88.3% had hookworm, Ascaris lumbricoides, Trichuris trichiura and any intestinal helminth infection, respectively. Cure rates were 97.4% for hookworm, 96.6% for A. lumbricoides and 30.8% for T. trichiura infections. Egg reduction rates (ERRs) were 99.8% for hookworm, 99.9% for A. lumbricoides and 83.1% for T. trichiura infections. Mild and transient symptoms were observed among the participants which were quite frequent. In conclusion, a 400 mg single oral dose of ABZ was effective against hookworm and A. lumbricoides but less efficacious against T. trichiura infection. The drug resulted in high ERRs for hookworm, A. lumbricoides and T. trichiura. Administration of the drug in repeated doses or in combination with other drugs might be necessary.     

Molecular Differentiation of Opisthorchis viverrini and Clonorchis sinensis Eggs by Multiplex Real-Time PCR with High Resolution Melting Analysis

Opisthorchis viverrini and Clonorchis sinensis are parasites known to be carcinogenic and causative agents of cholangiocarcinoma in Asia. The standard method for diagnosis for those parasite infections is stool examination to detect parasite eggs. However, the method has low sensitivity, and eggs of O. viverrini and C. sinensis are difficult to distinguish from each other and from those of some other trematodes. Here, we report a multiplex real-time PCR coupled with high resolution melting (HRM) analysis for the differentiation of O. viverrini and C. sinensis eggs in fecal samples. Using 2 pairs of species-specific primers, DNA sequences from a portion of the mitochondrial NADH dehydrogenase subunit 2 (nad 2) gene, were amplified to generate 209 and 165 bp products for O. viverrini and C. sinensis, respectively. The distinct characteristics of HRM patterns were analyzed, and the melting temperatures peaked at 82.4±0.09℃ and 85.9±0.08℃ for O. viverrini and C. sinensis, respectively. This technique was able to detect as few as 1 egg of O. viverrini and 2 eggs of C. sinensis in a 150 mg fecal sample, which is equivalent to 7 and 14 eggs per gram of feces, respectively. The method is species-specific, rapid, simple, and does not require fluorescent probes or post-PCR processing for discrimination of eggs of the 2 species. It offers a new tool for differentiation and detection of Asian liver fluke infections in stool specimens.     

Families Opisthorchiidae and Heterophyidae: are they distinct?

Superfamily Opisthorchioidea Looss, 1899 consists of three well-known families, Opisthorchiidae, Heterophyidae, and Cryptogonimidae, with basic similarities in morphology and life-cycles. Many species in the first two of these families are human pathogens, such as Opisthorchis viverrini, O. felineus, Clonorchis sinensis, Haplorchis spp. and Metagonimus spp. Recently, a molecular phylogenetic study on the classification of Digenea revealed a paraphyletic relationship between Opisthorchiidae and Heterophyidae. For our study, we gathered and analyzed all available data in GenBank, together with new data of nuclear 18S ribosomal DNA and ribosomal internal transcribed spacer 2 (ITS2) sequences of the families within the Opisthorchioidea. Maximum likelihood and Bayesian inference analyses suggested that families Opisthorchiidae and Heterophyidae are inseparable from each other, with the former nested within the latter. Groupings in molecular trees are generally consistent with morphological features used in taxonomy.     

Prevalence of Helminthic Infections among Inhabitants of Lao PDR

The prevalence of helminthic infections was surveyed on a total of 6,178 residents (males 2,549 and females 3,629) in 102 villages of 9 provinces in Lao PDR between 2007 and 2011 under the project of Korea-Laos Collaborative Project for Control of Foodborne Trematode Infections in Lao PDR. Fecal specimens were collected and examined by the Kato-Katz thick smear and Stoll''s egg counting techniques. The overall liver/intestinal helminth egg positive rate was 71.9% with a single or mixed infections with Opisthorchis viverrini and minute intestinal flukes (Ov/MIF), Ascaris lumbricoides, hookworms, Trichuris trichiura, Trichostrongylus sp., echinostomes, Taenia spp., and others. Ov/MIF revealed the highest prevalence (55.6%) followed by hookworms (27.8%) and T. trichiura (6.5%). The endemic regions with the highest prevalence of Ov/MIF were Savannakhet, Khammouane, Vientiane (Nam Ngum), Champasak (Khong Island), and Saravane Province. High prevalences of A. lumbricoides (33.8%), hookworms (47.8%), and T. trichiura (32.6%) were observed in Phongsaly, Luang Prabang, and Vientiane (Nam Ngum) areas, respectively. The results of this study highlight helminth parasites of current public health significance in different areas of Lao PDR.     

How Long Can Stool Samples Be Fixed for an Accurate Diagnosis of Soil-Transmitted Helminth Infection Using Mini-FLOTAC?

Background

Kato-Katz is a widely used method for the diagnosis of soil-transmitted helminth infection. Fecal samples cannot be preserved, and hence, should be processed on the day of collection and examined under a microscope within 60 min of slide preparation. Mini-FLOTAC is a technique that allows examining fixed fecal samples. We assessed the performance of Mini-FLOTAC using formalin-fixed stool samples compared to Kato-Katz and determined the dynamics of prevalence and intensity estimates of soil-transmitted helminth infection over a 31-day time period.

Methodology

The study was carried out in late 2013 on Pemba Island, Tanzania. Forty-one children were enrolled and stool samples were subjected on the day of collection to a single Kato-Katz thick smear and Mini-FLOTAC examination; 12 aliquots of stool were fixed in 5% formalin and subsequently examined by Mini-FLOTAC up to 31 days after collection.

Principal Findings

The combined results from Kato-Katz and Mini-FLOTAC revealed that 100% of children were positive for Trichuris trichiura, 85% for Ascaris lumbricoides, and 54% for hookworm. Kato-Katz and Mini-FLOTAC techniques found similar prevalence estimates for A. lumbricoides (85% versus 76%), T. trichiura (98% versus 100%), and hookworm (42% versus 51%). The mean eggs per gram of stool (EPG) according to Kato-Katz and Mini-FLOTAC was 12,075 and 11,679 for A. lumbricoides, 1,074 and 1,592 for T. trichiura, and 255 and 220 for hookworm, respectively. The mean EPG from day 1 to 31 of fixation was stable for A. lumbricoides and T. trichiura, but gradually declined for hookworm, starting at day 15.

Conclusions/Significance

The findings of our study suggest that for a qualitative diagnosis of soil-transmitted helminth infection, stool samples can be fixed in 5% formalin for at least 30 days. However, for an accurate quantitative diagnosis of hookworm, we suggest a limit of 15 days of preservation. Our results have direct implication for integrating soil-transmitted helminthiasis into transmission assessment surveys for lymphatic filariasis.     

Prevalence of Intestinal Helminths among Inhabitants of Cambodia (2006-2011)

In order to investigate the status of intestinal helminthic infections in Cambodia, epidemiological surveys were carried out on a national scale, including 19 provinces. A total of 32,201 fecal samples were collected from schoolchildren and adults between 2006 and 2011 and examined once by the Kato-Katz thick smear technique. The overall egg positive rate of intestinal helminths was 26.2%. The prevalence of hookworms was the highest (9.6%), followed by that of Opisthorchis viverrini/minute intestinal flukes (Ov/MIF) (5.7%), Ascaris lumbricoides (4.6%), and Trichuris trichiura (4.1%). Other types of parasites detected were Enterobius vermicularis (1.1%), Taenia spp. (0.4%), and Hymenolepis spp. (0.2%). The northwestern regions such as the Siem Reap, Oddar Meanchey, and Banteay Meanchey Provinces showed higher prevalences (17.4-22.3%) of hookworms than the other localities. The southwestern areas, including Koh Kong and Preah Sihanouk Provinces showed higher prevalences of A. lumbricoides (17.5-19.2%) and T. trichiura (6.1-21.0%). Meanwhile, the central and southern areas, in particular, Takeo and Kampong Cham Provinces, showed high prevalences of Ov/MIF (23.8-24.0%). The results indicate that a considerably high prevalence of intestinal helminths has been revealed in Cambodia, and thus sustained national parasite control projects are necessary to reduce morbidity due to parasitic infections in Cambodia.     

Risk Factors of Clonorchis sinensis Human Infections in Endemic Areas,Haman-Gun,Republic of Korea: A Case-Control Study

Clonorchis sinensis is the most common fish-borne intestinal parasite in Korea. The aim of the present investigation was to survey the status of C. sinensis infection and analyze associated risk factors in residents of Haman-gun, Gyeongsangnam-do. A total of 5,114 residents from 10 administrative towns/villages voluntarily agreed to participate in the study, which comprised fecal examination, a questionnaire survey for risk factors, ultrasonography, and enzyme-linked immunosorbent assay for cancer biomarker detection in the blood. We detected C. sinensis eggs in 5.3% of the subjects. By region, Gunbuk-myeon had the highest number of residents with C. sinensis eggs. The infection rate and intensity were higher in male than in female residents. Based on the risk factor questionnaire, infection was highly associated with drinking, a history of C. sinensis infection, and the practice of eating of raw freshwater fish. Extension of the bile duct, infection intensity, and cancer biomarker detection significantly correlated with the presence of eggs in the study population. In conclusion, the development of feasible, long-term control policies and strategies for the elimination of C. sinensis in Korea is still required.     

Patent Human Infections with the Whipworm,Trichuris trichiura,Are Not Associated with Alterations in the Faecal Microbiota

Background

The soil-transmitted helminth (STH), Trichuris trichiura colonises the human large intestine where it may modify inflammatory responses, an effect possibly mediated through alterations in the intestinal microbiota. We hypothesised that patent T. trichiura infections would be associated with altered faecal microbiota and that anthelmintic treatment would induce a microbiota resembling more closely that observed in uninfected individuals.

Materials and Methods

School children in Ecuador were screened for STH infections and allocated to 3 groups: uninfected, T. trichiura only, and mixed infections with T. trichiura and Ascaris lumbricoides. A sample of uninfected children and those with T. trichiura infections only were given anthelmintic treatment. Bacterial community profiles in faecal samples were studied by 454 pyrosequencing of 16 S rRNA genes.

Results

Microbiota analyses of faeces were done for 97 children: 30 were uninfected, 17 were infected with T. trichiura, and 50 with T. trichiura and A. lumbricoides. Post-treatment samples were analyzed for 14 children initially infected with T. trichiura alone and for 21 uninfected children. Treatment resulted in 100% cure of STH infections. Comparisons of the microbiota at different taxonomic levels showed no statistically significant differences in composition between uninfected children and those with T. trichiura infections. We observed a decreased proportional abundance of a few bacterial genera from the Clostridia class of Firmicutes and a reduced bacterial diversity among children with mixed infections compared to the other two groups, indicating a possible specific effect of A. lumbricoides infection. Anthelmintic treatment of children with T. trichiura did not alter faecal microbiota composition.

Discussion

Our data indicate that patent human infections with T. trichiura may have no effect on faecal microbiota but that A. lumbricoides colonisation might be associated with a disturbed microbiota. Our results also catalogue the microbiota of rural Ecuadorians and indicate differences with individuals from more urban industrialised societies.     

Prevalence of Clonorchis sinensis Infection among Residents along 5 Major Rivers in the Republic of Korea

Clonorchis sinensis is currently the most important parasite affecting public health problems in the Republic of Korea. We investigated the prevalence of C. sinensis infection among residents living along 5 major rivers in Korea. A total of 42,562 individual stool samples were collected from 37 localities and examined using the formalin-ether sedimentation technique. Helminth eggs were detected in 4,052 (9.5%) residents and 3,586 (8.4%) were infected with C. sinensis. The egg positive rate of C. sinensis in Nakdong, Seomjin, Geum, Yeongsan, and Han River was 11.7%, 9.9%, 6.5%, 3.1%, and 1.0%, respectively. The overall prevalence of clonorchiasis by sex was 11.2% in males and 6.2% in females. The age-prevalence was the highest in the 50-59 years band. It has been reconfirmed that the endemicity of clonorchiasis is higher in southern areas of Korea, especially along Nakdong and Seomjin Rivers. A combination of continuous control programs with health education initiatives is urgently required in these highly endemic areas of clonorchiasis in Korea.     

Field evaluation of the gut microbiome composition of pre-school and school-aged children in Tha Song Yang,Thailand, following oral MDA for STH infections

Soil-transmitted helminths, such as roundworms (Ascaris lumbricoides), whipworms (Trichuris trichiura) and hookworms (Necator americanus and Ancylostoma spp.), are gastrointestinal parasites that occur predominantly in low- to middle-income countries worldwide and disproportionally impact children. Depending on the STH species, health status of the host and infection intensity, direct impacts of these parasites include malnutrition, anaemia, diarrhoea and physical and cognitive stunting. The indirect consequences of these infections are less well understood. Specifically, gastrointestinal infections may exert acute or chronic impacts on the natural gut microfauna, leading to increased risk of post-infectious gastrointestinal disorders, and reduced gut and overall health through immunomodulating mechanisms. To date a small number of preliminary studies have assessed the impact of helminths on the gut microbiome, but these studies are conflicting. Here, we assessed STH burden in 273 pre-school and school-aged children in Tha Song Yang district, Tak province, Thailand receiving annual oral mebendazole treatment. Ascaris lumbricoides (107/273) and Trichuris trichiura (100/273) were the most prevalent species and often occurred as co-infections (66/273). Ancylostoma ceylanicum was detected in a small number of children as well (n = 3). All of these infections were of low intensity (<4,999 or 999 eggs per gram for Ascaris and Trichuris respectively). Using this information, we characterised the baseline gut microbiome profile and investigated acute STH-induced alterations, comparing infected with uninfected children at the time of sampling. We found no difference between these groups in bacterial alpha-diversity, but did observe differences in beta-diversity and specific differentially abundant OTUs, including increased Akkermansia muciniphila and Bacteroides coprophilus, and reduced Bifidobacterium adolescentis, each of which have been previously implicated in STH-associated changes in the gut microfauna.     

Tribendimidine and albendazole for treating soil-transmitted helminths, Strongyloides stercoralis and Taenia spp.: open-label randomized trial

Background

Tribendimidine is an anthelminthic drug with a broad spectrum of activity. In 2004 the drug was approved by Chinese authorities for human use. The efficacy of tribendimidine against soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura) has been established, and new laboratory investigations point to activity against cestodes and Strongyloides ratti.

Methodology/Principal Findings

In an open-label randomized trial, the safety and efficacy of a single oral dose of albendazole or tribendimidine (both drugs administered at 200 mg for 5- to 14-year-old children, and 400 mg for individuals ≥15 years) against soil-transmitted helminths, Strongyloides stercoralis, and Taenia spp. were assessed in a village in Yunnan province, People''s Republic of China. The analysis was on a per-protocol basis and the trial is registered with controlled-trials.com (number ISRCTN01779485). Both albendazole and tribendimidine were highly efficacious against A. lumbricoides and, moderately, against hookworm. The efficacy against T. trichiura was low. Among 57 individuals who received tribendimidine, the prevalence of S. stercoralis was reduced from 19.3% to 8.8% (observed cure rate 54.5%, p = 0.107), and that of Taenia spp. from 26.3% to 8.8% (observed cure rate 66.7%, p = 0.014). Similar prevalence reductions were noted among the 66 albendazole recipients. Taking into account “new” infections discovered at treatment evaluation, which were most likely missed pre-treatment due to the lack of sensitivity of available diagnostic approaches, the difference between the drug-specific net Taenia spp. cure rates was highly significant in favor of tribendimidine (p = 0.001). No significant adverse events of either drug were observed.

Conclusions/Significance

Our results suggest that single-dose oral tribendimidine can be employed in settings with extensive intestinal polyparasitism, and its efficacy against A. lumbricoides and hookworm was confirmed. The promising results obtained with tribendimidine against S. stercoralis and Taenia spp. warrant further investigations. In a next step, multiple-dose schedules should be evaluated.     

Survey of Zoonotic Trematode Metacercariae in Fish from Irrigation Canal of Togyo-jeosuji (Reservoir) in Cheorwon-gun,Gangwon-do,Republic of Korea

The infection status of zoonotic trematode metacercariae (ZTM) was investigated in total 568 freshwater fishes (19 species) from the irrigation canal of Togyo-jeosuji (Reservoir) in Cheorwon-gun, Gangwon-do, the Republic of Korea for 3 years (2018–2020). All fishes were examined using the artificial digestion method. The metacercariae of Clonorchis sinensis (CsMc) were detected in 180 (43.8%) out of 411 fish of positive species, and their infection intensity was 38 per fish infected (PFI). Especially, in 2 fish species, i.e., Pseudorasbora parva and Puntungia herzi, the prevalence was 82.1% and 31.3%, and the infection intensity with CsMc was 88 and 290 PFI, respectively. Metagonimus spp. metacercariae (MsMc) were found in 403 (74.1%) out of 544 fish of positive species, and their infection intensity was 62 PFI. In the pale chub, Zacco platypus, the prevalence of MsMc was 98.6%, and their infection intensity was 144 PFI. Centrocestus armatus metacercariae were detected in 171 (38.9%) out of 440 fish of positive species, and their infection intensity was 1,844 PFI. Echinostoma spp. metacercariae were found in 94 (19.6%) out of 479 fish of positive species, and their infection intensity was 3 PFI. Metorchis orientalis metacercariae were detected in 43 (29.3%) out of 147 fish of positive species, and their infection intensity was 4 PFI. By the present study, it has been confirmed that some species of ZTM, including CsMc and MsMc, are prevalent in fishes from the irrigation canal of Togyo-jeosuji in Cheorwon-gun, Gangwon-do, Korea.