RESUMEN
We performed a review of published and gray literature of human Hymenolepis diminuta cases across Europe up to July 2022. Of all detectable publications and records, we further analyzed only those that contained demographic, clinical or epidemiological data regarding the infected subjects. Additionally, one case of hymenolepiasis in a 16-mo-old boy living in the urban part of Belgrade was included in the analysis. Published studies were based in 13/50 European countries and identified 104 laboratory-confirmed cases in total. Almost one-half (49%) of all cases originated from Mediterranean countries. Among symptomatic children, the infection most often manifested with diarrhea, abdominal pain, allergic reaction and behavioral changes. The diagnosis was made by the detection and identification of H. diminuta eggs or parts of strobila in stool samples, although cases of misdiagnosis were also reported. The parasite clearance was established with praziquantel or niclosamide, while the administration of albendazole or mebendazole led to unfavorable results. Future multicentric prospective studies focused on infection screening and the gathering of detailed sociodemographic and clinical data could provide an updated insight into the true distribution and characteristics of H. diminuta infection across Europe.
Asunto(s)
Antihelmínticos , Himenolepiasis , Hymenolepis diminuta , Praziquantel , Humanos , Himenolepiasis/epidemiología , Himenolepiasis/tratamiento farmacológico , Himenolepiasis/diagnóstico , Masculino , Europa (Continente)/epidemiología , Animales , Praziquantel/uso terapéutico , Antihelmínticos/uso terapéutico , Lactante , Femenino , Niño , Albendazol/uso terapéutico , Preescolar , Heces/parasitología , Niclosamida/uso terapéutico , Mebendazol/uso terapéutico , Diarrea/parasitología , Diarrea/epidemiologíaRESUMEN
The leaves of Phlogacanthus thyrsiflorus are used as an anthelmintic remedy by the tribal communities of upper Assam in India. The present study was carried out to validate the anthelmintic credentials of this plant. Mature and larval Hymenolepis diminuta worms were exposed to varying concentration of methanolic leaf extract of plant and parasites were observed for paralysis and mortality. At the end of the experiment, worms were collected and processed for scanning electron microscopy (SEM) study to observe the effect of extract on tegument of parasite. The in vivo study was carried out in H. diminuta-rat model with 200, 400 and 800 mg/kg concentrations of extract. The in vivo anthelmintic efficacy was assessed by reductions in egg per gram (EPG) and worm counts after necropsy of animals. In vitro studies revealed the earliest mortality of larval worms in 1.05 ± 0.04 h by 30 mg/ml concentration and of adult worms in 2.05 ± 0.08 h. SEM study revealed extensive damage to the suckers, body tegument and microtriches of worms treated with 30 mg/ml concentration of extract. In in-vivo studies, 800 mg/kg dose of extract showed highest efficacy, with 59% and 54.25% reduction in EPG counts and worm count against juvenile worms, and 63.16% and 66.75% reduction in EPG counts and worm counts, respectively against adult worms. Although the effects were comparatively less than the reference drug, nevertheless this study reveals that P. thyrsiflorus possess anthelmintic efficacy and justify its use in traditional medicine against intestinal-worm infections.
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The rat tapeworm Hymenolepis diminuta is a parasite that usually uses rats as a definitive host. It also infects humans and non-human primates. Human infections have been reported in 80 countries worldwide, including China. Nevertheless, nearly all the literature on human infections in China by the rat tapeworm is in Chinese journals, which are very difficult to access by readers outside China. The main aim of the current manuscript was to systematically review human infections by the rat tapeworm in China for readers inside and outside the country. Chinese characters for H. diminuta were used to search several databases, including Google Scholar. In total, 511 infections were reported in 24 Chinese provinces/autonomous regions, which surpassed 320 in Costa Rica as the country with the highest number of infections. Furthermore, three nationwide surveys on parasitic infections in the past 3 decades revealed detailed prevalence of this parasite along with that of roundworm, whipworm, hookworm and pinworm in Chinese populations. These data contribute to better understanding of this greatly neglected zoonosis in the world's most populated country.
Asunto(s)
Himenolepiasis , Hymenolepis diminuta , Humanos , Ratas , Animales , Himenolepiasis/epidemiología , Himenolepiasis/veterinaria , Himenolepiasis/parasitología , Zoonosis/epidemiología , China/epidemiología , PrevalenciaRESUMEN
Hymenolepis diminuta is a tapeworm commonly found worldwide in small rodents such as rats with occasional reports in other definitive hosts such as primates including chimpanzees and humans. It has not been reported in African green monkey (AGM, Chlorocebus sabaeus), and the parasite's molecular phenotype and phylogeny remain primitively sketchy. The aims of the current study were to determine if H. diminuta infected AGMs, to molecularly characterize H. diminuta and to review its infection in non-human primates. Feces of AGMs were examined visually for adult helminths and microscopically for eggs using centrifugation flotation. Total DNA extracted from eggs was amplified by PCR followed by DNA sequencing of targeted sequences of nuclear rRNA + internal transcribed spacers (ITS) and mitochondrial cox1. Phylogenetic analyses were performed. The DNA sequences of both nuclear rRNA + ITS and mitochondrial cox1 showed more than 98% and 99% identity to the known sequences respectively. Hymenolepis diminuta has been reported in various non-human primates with the highest prevalence of 38.5% in the white-headed capuchin monkey. The study presented here confirms that this tapeworm is capable of infecting various species of non-human primates with the first report of infections in AGM. Phylogenetic analyses of rRNA + ITS and mitochondrial cox1 demonstrated three separated clades I, II and III with the newly described AGM1 isolate belonging to the clade I. Whether these differences are at species level remains to be confirmed.
Asunto(s)
Himenolepiasis , Hymenolepis diminuta , Hymenolepis , Ratas , Animales , Humanos , Chlorocebus aethiops , Filogenia , ARN Ribosómico/genética , Himenolepiasis/epidemiología , Primates , Roedores/genética , Hymenolepis/genéticaRESUMEN
We report a case of Hymenolepis diminuta infection in a two years old boy living in Guilan Province, northern Iran diagnosed in 2019. The patient was complained of anorexia, weight loss, weakness and disturbed sleep. Stool examination revealed numerous eggs of H. diminuta. After treatment with a single dose of oral praziquantel, the patient recovered without evidence of the egg shedding in follow-up stool samples. Moreover, we performed detailed phylogenetic analysis of the H. diminuta comparing with other isolates deposited in GenBank database based on Cox1 gene. Based on BLAST analysis of Cox1 gene our sequence showed 97.4-99.2% similarity with those of H. diminuta available in GenBank. The present study recommends the importance of reporting the infection cases, in order to improve knowledge on epidemiology and control of the neglected disease.
RESUMEN
The tapeworm Hymenolepis diminuta is a common parasite of the small intestine in rodents but it can also infect humans. Due to its characteristics and ease of maintenance in the laboratory, H. diminuta is also an important model species in studies of cestodiasis, including the search for new drugs, treatments, diagnostics and biochemical processes, as well as its host-parasite interrelationships. A great deal of attention has been devoted to the immune response caused by H. diminuta in the host, and several studies indicate that infection with H. diminuta can reduce the severity of concomitant disease. Here, we present a critical review of the experimental research conducted with the use of H. diminuta as a model organism for over more than two decades (in the 21st century). The present review evaluates the tapeworm H. diminuta as a model organism for studying the molecular biology, biochemistry and immunology aspects of parasitology, as well as certain clinical applications. It also systematizes the latest research on this species. Its findings may contribute to a better understanding of the biology of tapeworms and their adaptation to parasitism, including complex correlations between H. diminuta and invertebrate and vertebrate hosts. It places particular emphasis on its value for the further development of modern experimental parasitology.
RESUMEN
Hymenolepis diminuta is primarily a rodent parasite that is ubiquitously distributed worldwide, but with only a few cases described as human infections. We report a case of Hymenolepis diminuta infection in a 15-month-old child, living in an urban setting, with no previous medical history. The patient presented with two episodes of seizures, and complaints of abdominal pain, vomiting, and diarrhea, with no apparent history of rodent contact. Furthermore, the patient's gastrointestinal symptoms were linked to the emission of suspected tapeworm proglottids in the feces. After excluding other possible etiologies, a diagnosis of Hymenolepis diminuta infection was made, based on the examination of characteristic eggs in a concentrated stool specimen. The infant was successfully treated with praziquantel and fully recovered. After two weeks, the stool sample was free of Hymenolepis diminuta eggs. The clinical follow-up over the next 3 years was normal. Hymenolepis diminuta is rarely found in humans, and, when present, the infection is frequently asymptomatic. Abdominal pain, irritability, itching, eosinophilia, and seizures have also been reported. In this paper, we report, for the first time in the literature, an infection with Hymenolepis diminuta in a Romanian infant who had atypical neurological presentation, with full recovery, without subsequent neurological sequelae.
RESUMEN
The study reveals the prevalence of a potential rodent-borne zoonotic helminth species, Hymenolepis diminuta in commensal rodents caught from irrigated and rain-fed areas of Swat, Pakistan. Three hundred and fifty rodents (269 rats and 81 mice) trapped during vegetative, flowering/fruiting and mature/harvesting stages of crops were studied from 2011-2013. Hymenolepisdiminuta eggs were identified on the basis of their shape, size, colour and markings on the surface of the egg shell and three pairs of embryonic hook-lets. Overall prevalence of H. diminuta was 3.14% (n=11/350). The highest prevalence 3.49% (n=5/143) of H. diminuta was noted at harvesting stages of the crops whereas the lowest 2.59% (n=2/77) during vegetative stage. Infection was higher in males 3.25% (n=7/215) than females 2.96% (n=4/135). Adult rodents were highly infected while no sub-adult was found infected. Infection was higher in mice 3.70% (3/81) than rats 2.69% (8/269) while no significance (p=1.0000:0.1250 to 32.00 CI). Rats and mice appears to show the most suitable reservoirs by hosting H. diminuta a zoonotic helminth. The presence of these rodents in all possible habitats can act as a main channel of transferring parasites through various habitats and can pose a hazard to humans in the area.
O estudo revela a prevalência de uma espécie potencial de helmintos zoonóticos transmitidos por roedores, Hymenolepis diminuta, em roedores comensais capturados em áreas irrigadas e alimentadas pela chuva de Swat, Paquistão. Trezentos e cinquenta roedores (269 ratos e 81 camundongos) presos durante os estágios vegetativo, floração/frutificação e maturidade/colheita das safras foram estudados de 2011-2013. Ovos de Hymenolepisdiminuta foram identificados com base em sua forma, tamanho, cor e marcações na superfície da casca do ovo e três pares de anzóis embrionários. A prevalência geral de H. diminuta foi de 3,14% (n = 11/350). A maior prevalência 3,49% (n = 5/143) de H. diminuta foi observada na fase de colheita das lavouras, enquanto a menor 2,59% (n = 2/77) durante a fase vegetativa. A infecção foi maior nos homens 3,25% (n = 7/215) do que nas mulheres 2,96% (n = 4/135). Roedores adultos foram altamente infectados, enquanto nenhum subadulto foi encontrado infectado. A infecção foi maior em camundongos 3,70% (3/81) do que em ratos 2,69% (8/269), embora sem significância (p = 1,0000: 0,1250 a 32,00 CI). Ratos e camundongos parecem mostrar os reservatórios mais adequados hospedando H. diminuta um helmintos zoonótico. A presença desses roedores em todos os habitats possíveis pode atuar como um canal principal de transferência de parasitas através de vários habitats e pode representar um perigo para os humanos na área.
Asunto(s)
Masculino , Femenino , Animales , Himenolepiasis/diagnóstico , Himenolepiasis/veterinaria , Muridae/parasitologíaRESUMEN
Abstract The study reveals the prevalence of a potential rodent-borne zoonotic helminth species, Hymenolepis diminuta in commensal rodents caught from irrigated and rain-fed areas of Swat, Pakistan. Three hundred and fifty rodents (269 rats and 81 mice) trapped during vegetative, flowering/fruiting and mature/harvesting stages of crops were studied from 2011-2013. Hymenolepisdiminuta eggs were identified on the basis of their shape, size, colour and markings on the surface of the egg shell and three pairs of embryonic hook-lets. Overall prevalence of H. diminuta was 3.14% (n=11/350). The highest prevalence 3.49% (n=5/143) of H. diminuta was noted at harvesting stages of the crops whereas the lowest 2.59% (n=2/77) during vegetative stage. Infection was higher in males 3.25% (n=7/215) than females 2.96% (n=4/135). Adult rodents were highly infected while no sub-adult was found infected. Infection was higher in mice 3.70% (3/81) than rats 2.69% (8/269) while no significance (p=1.0000:0.1250 to 32.00 CI). Rats and mice appears to show the most suitable reservoirs by hosting H. diminuta a zoonotic helminth. The presence of these rodents in all possible habitats can act as a main channel of transferring parasites through various habitats and can pose a hazard to humans in the area.
Resumo O estudo revela a prevalência de uma espécie potencial de helmintos zoonóticos transmitidos por roedores, Hymenolepis diminuta, em roedores comensais capturados em áreas irrigadas e alimentadas pela chuva de Swat, Paquistão. Trezentos e cinquenta roedores (269 ratos e 81 camundongos) presos durante os estágios vegetativo, floração/frutificação e maturidade/colheita das safras foram estudados de 2011-2013. Ovos de Hymenolepisdiminuta foram identificados com base em sua forma, tamanho, cor e marcações na superfície da casca do ovo e três pares de anzóis embrionários. A prevalência geral de H. diminuta foi de 3,14% (n = 11/350). A maior prevalência 3,49% (n = 5/143) de H. diminuta foi observada na fase de colheita das lavouras, enquanto a menor 2,59% (n = 2/77) durante a fase vegetativa. A infecção foi maior nos homens 3,25% (n = 7/215) do que nas mulheres 2,96% (n = 4/135). Roedores adultos foram altamente infectados, enquanto nenhum subadulto foi encontrado infectado. A infecção foi maior em camundongos 3,70% (3/81) do que em ratos 2,69% (8/269), embora sem significância (p = 1,0000: 0,1250 a 32,00 CI). Ratos e camundongos parecem mostrar os reservatórios mais adequados hospedando H. diminuta um helmintos zoonótico. A presença desses roedores em todos os habitats possíveis pode atuar como um canal principal de transferência de parasitas através de vários habitats e pode representar um perigo para os humanos na área.
RESUMEN
The study reveals the prevalence of a potential rodent-borne zoonotic helminth species, Hymenolepis diminuta in commensal rodents caught from irrigated and rain-fed areas of Swat, Pakistan. Three hundred and fifty rodents (269 rats and 81 mice) trapped during vegetative, flowering/fruiting and mature/harvesting stages of crops were studied from 2011-2013. Hymenolepisdiminuta eggs were identified on the basis of their shape, size, colour and markings on the surface of the egg shell and three pairs of embryonic hook-lets. Overall prevalence of H. diminuta was 3.14% (n=11/350). The highest prevalence 3.49% (n=5/143) of H. diminuta was noted at harvesting stages of the crops whereas the lowest 2.59% (n=2/77) during vegetative stage. Infection was higher in males 3.25% (n=7/215) than females 2.96% (n=4/135). Adult rodents were highly infected while no sub-adult was found infected. Infection was higher in mice 3.70% (3/81) than rats 2.69% (8/269) while no significance (p=1.0000:0.1250 to 32.00 CI). Rats and mice appears to show the most suitable reservoirs by hosting H. diminuta a zoonotic helminth. The presence of these rodents in all possible habitats can act as a main channel of transferring parasites through various habitats and can pose a hazard to humans in the area.
O estudo revela a prevalência de uma espécie potencial de helmintos zoonóticos transmitidos por roedores, Hymenolepis diminuta, em roedores comensais capturados em áreas irrigadas e alimentadas pela chuva de Swat, Paquistão. Trezentos e cinquenta roedores (269 ratos e 81 camundongos) presos durante os estágios vegetativo, floração/frutificação e maturidade/colheita das safras foram estudados de 2011-2013. Ovos de Hymenolepis diminuta foram identificados com base em sua forma, tamanho, cor e marcações na superfície da casca do ovo e três pares de anzóis embrionários. A prevalência geral de H. diminuta foi de 3,14% (n = 11/350). A maior prevalência 3,49% (n = 5/143) de H. diminuta foi observada na fase de colheita das lavouras, enquanto a menor 2,59% (n = 2/77) durante a fase vegetativa. A infecção foi maior nos homens 3,25% (n = 7/215) do que nas mulheres 2,96% (n = 4/135). Roedores adultos foram altamente infectados, enquanto nenhum subadulto foi encontrado infectado. A infecção foi maior em camundongos 3,70% (3/81) do que em ratos 2,69% (8/269), embora sem significância (p = 1,0000: 0,1250 a 32,00 CI). Ratos e camundongos parecem mostrar os reservatórios mais adequados hospedando H. diminuta um helmintos zoonótico. A presença desses roedores em todos os habitats possíveis pode atuar como um canal principal de transferência de parasitas através de vários habitats e pode representar um perigo para os humanos na área.
Asunto(s)
Animales , Femenino , Conejos , Ratas , Enfermedades de los Roedores/epidemiología , Hymenolepis diminuta , Helmintiasis Animal , Helmintos , MuridaeRESUMEN
BACKGROUND AND AIM: Trichuris trichiura and Hymenolepis diminuta are helminthic intestinal parasites that infect humans and other animals, including non-human primates. However, molecular detection of these parasites remains scarce in long-tailed macaques (Macaca fascicularis), which coexist with human communities in Thailand. Thus, this study aimed to molecularly confirm the occurrence of Trichuris spp. and Hymenolepis spp. infection and determine the species of both parasites that were found in long-tailed macaques. MATERIALS AND METHODS: A total of 200 fecal samples were randomly collected from long-tailed macaques living in Lopburi, Thailand, and tested based on polymerase chain reaction (PCR) assays for Trichuris spp. and Hymenolepis spp. infections. The PCR products were submitted for DNA purification and sequencing. Phylogenetic analysis was performed using the maximum likelihood method. RESULTS: Of 200 tested samples, three (1.5%) were positive for Trichuris spp. Sequence analysis of all positive samples revealed the presence of T. trichiura, while eight samples (8/200, 4%) positive for Hymenolepis spp. were classified as H. diminuta. No significant associations were found between parasite infection and sex of macaques. CONCLUSION: This study revealed that long-tailed macaques harbor T. trichiura and H. diminuta. These results suggested that local residents and tourists must pay attention to limiting contact with long-tailed macaques and take hygienic precautions to reduce the risk of zoonotic and anthroponotic transmission of these parasites between humans and long-tailed macaques.
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Poor socio-economic and unsanitary conditions are conducive to commensal rodent infestations, and these conditions are widespread in South Africa. Cestode species of zoonotic interest are highly prevalent in commensal rodents, such as invasive Rattus norvegicus, Rattus rattus, Rattus tanezumi, and indigenous Mastomys coucha, and have been frequently recovered from human stool samples. These cestode species have similar transmission dynamics to traditional soil-transmitted helminths (STHs), which ties them to infections associated with poverty and poor sanitation. Univariate analysis was used in the present study to determine the association between rodent-related factors and cestode prevalence, while ecological niche modelling was used to infer the potential distribution of the cestode species in South Africa. Cestode prevalence was found to be associated with older rodents, but it was not significantly associated with sex, and ectoparasite presence. The predicted occurrence for rodent-borne cestodes predominantly coincided with large human settlements, typically associated with significant anthropogenic changes. In addition, cestode parasite occurrence was predicted to include areas both inland and along the coast. This is possibly related to the commensal behaviour of the rodent hosts. The study highlights the rodent-related factors associated with the prevalence of parasites in the host community, as well as the environmental variables associated with parasite infective stages that influence host exposure. The application of geospatial modelling together with univariate analysis to predict and explain rodent-borne parasite prevalence may be useful to inform management strategies for targeted interventions.
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The leaf decoction of Sesbania sesban var. bicolor is used traditionally by Santhal tribe of Assam, India, for the treatment of intestinal helminthic infections. This study was conducted to evaluate the in vitro and in vivo anthelmintic efficacy of methanolic extract of S. sesban var. bicolor leaves using Hymenolepis diminuta-rat (cestode) and Syphacia obvelata-mice (nematode) as test parasites and models. Praziquantel (PZQ) and albendazole (ABZ) were used as reference drugs. At the highest concentration of 30 mg/ml of the plant extract, H. diminuta and S. obvelata showed mortality at 0.81 ± 0.01 h and 15.17 ± 0.05 h, respectively. The in vivo results substantiated the in vitro findings, and the extract showed a better cestocidal efficacy in a dose-dependent manner, whereby treatment of rats with 400 mg/kg of the plant extract caused 65.10% reduction in eggs per gram (EPG) of faeces and 56% reduction in worm counts. S. obvelata-infected mice treated at the same dose showed 34.32% and 47.08% reduction in EPG and worm counts at necropsy, respectively. The methanolic extract was subjected to bioassay-guided fractionation using different solvents and the ethyl acetate fraction proved to be the most active. This active fraction was subjected to column chromatography using varying concentrations of hexane:ethyl acetate. Maximum efficacy was observed in 7:3 hexane:ethyl acetate, where H. diminuta and S. obvelata showed mortality at 3.56 ± 0.12 h and 9.21 ± 0.02 h, respectively. This indicates that the isolated fraction contained the active component responsible for its anthelmintic activity, which substantiates the medicinal usage in traditional practice.
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Colonization by the benign tapeworm, Hymenolepis diminuta, has been associated with a reduction in intestinal inflammation and changes in bacterial microbiota. However, the role of microbiota in the tapeworm anti-inflammatory effect is not yet clear, and the aim of this study was to determine whether disruption of the microflora during worm colonization can affect the course of intestinal inflammation. We added a phase for disrupting the intestinal microbiota using antibiotics to the experimental design for which we previously demonstrated the protective effect of H. diminuta. We monitored the immunological markers, clinical parameters, bacterial microbiota, and histological changes in the colon of rats. After a combination of colonization, antibiotics, and colitis induction, we had four differently affected experimental groups. We observed a different course of the immune response in each group, but no protective effect was found. Rats treated with colonization and antibiotics showed a strong induction of the Th2 response as well as a significant change in microbial diversity. The microbial results also revealed differences in the richness and abundance of some bacterial taxa, influenced by various factors. Our data suggest that interactions between the tapeworm and bacteria may have a major impact on its protective effect.
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Like mammalian cells, helminth parasites are equipped with an array of enzymatic anti-oxidant system which has an adaptive strategy to cope up with several conditions of stress that arise from host immune response or drug treatment. Earlier, we had reported that three species of Senna, viz. S. alata, S. alexandrina and S. occidentalis leaf extracts caused severe morphological and biochemical alterations in the zoonotic parasite Hymenolepis diminuta. To understand whether the leaf extracts of the three species of Senna have any effect on the enzymatic anti-oxidant system in H.diminuta or not, the present study was investigated on the mechanism of action of these leaf extracts on the anti-oxidant system of the parasite. The viability of the parasite was assessed by MTT reduction assay, chromatin condensation through Hoechst staining of tissue and DNA fragmentation assay, and the oxidative enzymes of the parasite were estimated biochemically. Activity of superoxide dismutase, catalase, glutathione S- transferase and glutathione peroxidase were found to be increased in all the treated parasites from that of the control, with S. alata showed the highest increased amongst the three plant species in all the enzymes, at 331.0 %, 215.4 %, 85.4 % and 65.5 % respectively. Upliftment of apoptotic protein CED-3, CED-4 and EGL-1 and down regulation of anti-apototic protein CED-9 was visualised in all treated paraites. The redox imbalance triggered by these leaf extracts resulted in the activation of apoptotic pathway that led to death of the parasite. Our results demonstrated that the leaf extracts of the three Senna plant species could open new insight for an affordable natural anthelmintic with high efficacy and less toxicity.
Asunto(s)
Antihelmínticos/farmacología , Apoptosis/efectos de los fármacos , ADN de Helmintos/genética , Hymenolepis diminuta/efectos de los fármacos , Especies Reactivas de Oxígeno/agonistas , Senna/química , Animales , Antihelmínticos/aislamiento & purificación , Apoptosis/genética , Caspasas/genética , Caspasas/metabolismo , Catalasa/genética , Catalasa/metabolismo , Fragmentación del ADN/efectos de los fármacos , ADN de Helmintos/antagonistas & inhibidores , ADN de Helmintos/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Glutatión Peroxidasa/genética , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Hymenolepis diminuta/genética , Hymenolepis diminuta/crecimiento & desarrollo , Hymenolepis diminuta/metabolismo , Extractos Vegetales/química , Hojas de la Planta/química , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismoRESUMEN
Rodents are reservoirs and hosts of several pathogens around the world, including zoonotic parasite species. This study aimed to determine the occurrence of zoonotic gastrointestinal helminths in rodents captured inside households in a rural community from southern Guatemala. Sixty-nine rodents were captured in 33% (49/148) of the surveyed households, including Rattus rattus, Rattus norvegicus, Mus musculus, and Sigmodon hispidus. Thirty-six percent (25/69) of these rodents (3 Rattus and 22 Mus musculus), from 45% (22/49) of the households, were parasitized with at least 1 gastrointestinal helminth species. Helminths from 6 species were identified: Hymenolepis diminuta, Moniliformis moniliformis, Heterakis spumosa, Nippostrongylus sp., Strongyloides sp., and Syphacia sp. Two zoonotic species were found in Rattus, H. diminuta in R. rattus (1/6), and M. moniliformis in R. norvegicus (1/1). Coinfection with other non-zoonotic helminth parasites, such as He. spumosa and Strongyloides sp., also was observed in the Rattus genus. Mus musculus had only non-zoonotic helminths: He. spumosa, Nippostrongylus sp., and Syphacia sp. being the most common, and He. spumosa (96%) followed by Nippostrongylus sp. (48%), with a higher presence in males than females, with a similar proportion in adult and young individuals. This is the first report of zoonotic and non-zoonotic helminths parasites in rodents from Guatemala.
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Helmintiasis Animal/parasitología , Ratones/parasitología , Ratas/parasitología , Enfermedades de los Roedores/parasitología , Zoonosis/parasitología , Animales , Reservorios de Enfermedades/parasitología , Composición Familiar , Femenino , Guatemala/epidemiología , Helmintiasis Animal/epidemiología , Humanos , Masculino , Enfermedades de los Roedores/epidemiología , Población RuralRESUMEN
The interaction of the rat tapeworm, Hymenolepis diminuta, with its intermediate beetle host, Tribolium confusum, is a well-studied model system. However, there is so much variation in the methods and designs of the studies that it is difficult to draw comparisons. This study simultaneously compared several aspects of the infection protocol including beetle age, sex, density and mating status; parasite egg condition, infection environment humidity and the times for the three steps of infection: starvation, feeding and post-feeding development. Although statistically limited by low prevalence and intensity levels, we were able to detect the relative effects of the variables. The effects of these variables on prevalence (percent infection) and intensity (mean number of cysticercoids) do not necessarily correlate with each other. Egg condition, reduced starvation times, higher beetle density and longer development times reduced prevalence. However, differences in intensity were only detected with older beetles. When coupled with survivorship data, our study found that our current infection protocol is optimal for infection success. However, the results suggest extending the study to other intermediate hosts and the inclusion of additional variables.
Asunto(s)
Bioensayo/métodos , Himenolepiasis/parasitología , Hymenolepis diminuta/crecimiento & desarrollo , Tribolium/parasitología , Animales , Escarabajos , Interacciones Huésped-Parásitos , Estadios del Ciclo de VidaRESUMEN
Hymenolepidid cestodes of synanthropic rodents represent a risk for public health. In order to describe the occurrence of hymenolepidids in children and the role of rodents as a potential source of infection, we conducted a morphological and molecular survey on cestodes in two rural villages from Yucatan, Mexico. One hundred and thirty-five stool samples from children (64 from Paraíso and 71 from Xkalakdzonot), 233 Mus musculus (159 from Paraíso and 74 from Xkalakdzonot) and 125 Rattus rattus (7 from Paraíso and 118 from Xkalakdzonot) were analyzed for the presence of cestodes. Three hymenolepidid species were identified morphologically: Hymenolepis nana in 7.8% of children from Paraíso, Hymenolepis microstoma in 4.4% of M. musculus from Paraíso and Hymenolepis diminuta in 15.3% of R. rattus from Xkalakdzonot. The molecular characterization and phylogenetic analysis based on mitochondrial cytochrome c subunit 1 (CO1) gene and ribosomal internal transcribed spacer 1 (ITS1) region, confirmed the identity of the three cestodes isolated from Yucatan. Phylogeny of the CO1 gene identified intraspecific genetic differences within H. nana ranging from 0 to 5%, in H. microstoma from 0 to 0.4%, and in H. diminuta ranged from 0 to 6.5% which suggests, the presence of complex species within H. nana and H. diminuta infecting humans and rodents, as reported by other authors. Based on the morphological and molecular results, and the epidemiological evidence, infections with H. nana suggest a non-zoonotic transmission; however, the presence of H. microstoma and H. diminuta in synanthropic rodents serve as a possible source for human infection.
Asunto(s)
Himenolepiasis/epidemiología , Himenolepiasis/veterinaria , Hymenolepis/aislamiento & purificación , Ratones , Ratas , Enfermedades de los Roedores/epidemiología , Adolescente , Animales , Niño , Preescolar , Humanos , Himenolepiasis/parasitología , Hymenolepis diminuta/aislamiento & purificación , Hymenolepis nana/aislamiento & purificación , Lactante , México/epidemiología , Filogenia , Prevalencia , Enfermedades de los Roedores/parasitología , RoedoresRESUMEN
Tapeworms grow at rates rivaling the fastest-growing metazoan tissues. To propagate they shed large parts of their body; to replace these lost tissues they regenerate proglottids (segments) as part of normal homeostasis. Their remarkable growth and regeneration are fueled by adult somatic stem cells that have yet to be characterized molecularly. Using the rat intestinal tapeworm, Hymenolepis diminuta, we find that regenerative potential is regionally limited to the neck, where head-dependent extrinsic signals create a permissive microenvironment for stem cell-driven regeneration. Using transcriptomic analyses and RNA interference, we characterize and functionally validate regulators of tapeworm growth and regeneration. We find no evidence that stem cells are restricted to the regeneration-competent neck. Instead, lethally irradiated tapeworms can be rescued when cells from either regeneration-competent or regeneration-incompetent regions are transplanted into the neck. Together, the head and neck tissues provide extrinsic cues that regulate stem cells, enabling region-specific regeneration in this parasite.
Asunto(s)
Estructuras Animales/crecimiento & desarrollo , Hymenolepis diminuta/crecimiento & desarrollo , Regeneración , Células Madre/fisiología , Estructuras Animales/efectos de la radiación , Animales , Hymenolepis diminuta/efectos de la radiaciónRESUMEN
Studies in animal models and humans suggest that intentional exposure to helminths or helminth-derived products may hold promise for treating chronic inflammatory-associated diseases (CIADs). Although the mechanisms underlying 'helminth therapy' are being evaluated, little attention has been paid to the actual organisms in use. Here we examine the notion that, because of the complexity of biological symbiosis, intact helminths rather than helminth-derived products are likely to prove more useful for clinical purposes. Further, weighing potential cost/benefit ratios of various helminths along with other factors, such as feasibility of production, we argue that the four helminths currently in use for CIAD treatments in humans were selected more by happenstance than by design, and that other candidates not yet tested may prove superior.