A human case of Hymenolepis diminuta in a child from eastern Sicily

Human infections by Hymenolepis diminuta in Europe: a case report and literature review

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.

Gallic acid and Catechin induce morphological alterations on the zoonotic parasite Hymenolepis diminuta

Tapeworm infections cause insidious and irreversible effects in the infected individuals and some of them have already shown resistance to available drugs. A search for alternative treatment is urgently required. Phenolic compounds are amongst the most researched natural substances for their medicinal use. The present study aims to determine anthelmintic efficacy of two polyphenols Gallic acid and Catechin against the zoonotic rat tapeworm Hymenolepis diminuta. Both compounds are potent anti-oxidants and play major roles in combating pathogens, while their anthelmintic property according to our knowledge is yet to be explored. The parasite model H. diminuta was procured from intestine of infected rats raised in our laboratory. Two sets of parasites were treated in vitro with 5, 10, 20 and 40 mg/ml concentrations of each Gallic Acid and Catechin separately, another set of parasites were treated with standard dose of Praziquantel in RPMI 1640, while still another set of worms were kept in RPMI 1640 at 37 ± 10C with 1% Dimethyl sulfoxide as control. Motility and structural alterations were the parameters assessed for anthelmintic efficacy of the compounds. After paralysis the worms were processed for morphological, histological, and ultrastructural study and observed under light and electron microscope. Dose-dependent efficacy was observed in both compounds. Shrinkage of suckers, deformed proglottids and architectural alteration of the tegument were observed throughout the body of treated parasites compared to control. Although in terms of time taken for paralysis and mortality Gallic acid was more effective than Catechin, the degree of morphological aberrations caused were almost similar, except histological alteration was more in Catechin treated worms than in Gallic acid. Nevertheless, both Gallic acid and Catechin are suggested to possess anthelmintic efficacy besides other health benefits but extended studies are required to compare their efficacy.

Hymenolepis diminuta Infection in a Romanian Child from an Urban Area

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.

Molecular identification of Trichuris trichiura and Hymenolepis diminuta in long-tailed macaques (Macaca fascicularis) in Lopburi, Thailand

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.

Worldwide overview of human infections with Hymenolepis diminuta

Hymenolepis diminuta is a zoonotic cestode parasitizing the small intestine of rodents (definitive hosts). Humans can accidentally enter into the life cycle of this tapeworm via the ingestion of infected insects (intermediate hosts) containing cestode cysticercoids in their body cavity. More than two centuries after the first record in humans, there are no accurate estimates of the number of human cases around the world. In order to have a more precise idea about the number of human cases with H. diminuta and the current status of the disease (hymenolepiasis) worldwide, we conducted a literature review of published records on human infection with H. diminuta. One thousand five hundred and sixty-one published records of infection with H. diminuta from 80 countries were identified. This review presents an estimate of the number of human cases with H. diminuta and a current overview of the prevalence, geographic distribution, symptoms, diagnosis, exposure to infective stages, and therapeutic approaches for this underestimated zoonotic tapeworm.

Morphological and molecular identification of hymenolepidid cestodes in children and synanthropic rodents from rural Mexico

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.

Occurrence of Gastrointestinal Parasites in Small Mammals from Germany

An increase in zoonotic infections in humans in recent years has led to a high level of public interest. However, the extent of infestation of free-living small mammals with pathogens and especially parasites is not well understood. This pilot study was carried out within the framework of the "Rodent-borne pathogens" network to identify zoonotic parasites in small mammals in Germany. From 2008 to 2009, 111 small mammals of 8 rodent and 5 insectivore species were collected. Feces and intestine samples from every mammal were examined microscopically for the presence of intestinal parasites by using Telemann concentration for worm eggs, Kinyoun staining for coccidia, and Heidenhain staining for other protozoa. Adult helminths were additionally stained with carmine acid for species determination. Eleven different helminth species, five coccidians, and three other protozoa species were detected. Simultaneous infection of one host by different helminths was common. Hymenolepis spp. (20.7%) were the most common zoonotic helminths in the investigated hosts. Coccidia, including Eimeria spp. (30.6%), Cryptosporidium spp. (17.1%), and Sarcocystis spp. (17.1%), were present in 40.5% of the feces samples of small mammals. Protozoa, such as Giardia spp. and amoebae, were rarely detected, most likely because of the repeated freeze-thawing of the samples during preparation. The zoonotic pathogens detected in this pilot study may be potentially transmitted to humans by drinking water, smear infection, and airborne transmission.

Infection with Hymenolepis diminuta (Rodolphi, 1819) in a Child from North of Iran: Case Report

We report a human case of Hymenolepis diminuta infection in Guilan Province, northern part of Iran in 2017. The patient was a 15-month-old boy with gastrointestinal symptoms. In stool examination, eggs of H. diminuta was found based on morphological characteristic. The infant was successfully treated with a single oral dose of praziquantel, and then completely recovered. For the first time, we report human infection with this species in north of Iran.

Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm’s scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host’s gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host’s tissues and organs.

The helminth community of a population of Rattus norvegicus from an urban Brazilian slum and the threat of zoonotic diseases

Urban slums provide suitable conditions for infestation by rats, which harbour and shed a wide diversity of zoonotic pathogens including helminths. We aimed to identify risk factors associated with the probability and intensity of infection of helminths of the digestive tract in an urban slum population of Rattus norvegicus. Among 299 rats, eleven species/groups of helminths were identified, of which Strongyloides sp., Nippostrongylus brasiliensis and, the human pathogen, Angiostrongylus cantonensis were the most frequent (97, 41 and 39%, respectively). Sex interactions highlighted behavioural differences between males and females, as eg males were more likely to be infected with N. brasiliensis where rat signs were present, and males presented more intense infections of Strongyloides sp. Moreover, rats in poor body condition had higher intensities of N. brasiliensis. We describe a high global richness of parasites in R. norvegicus, including five species known to cause disease in humans. Among these, A. cantonensis was found in high prevalence and it was ubiquitous in the study area - knowledge which is of public health importance. A variety of environmental, demographic and body condition variables were associated with helminth species infection of rats, suggesting a comparable variety of risk factors for humans.

Intestinal Parasitic Infections and Environmental Water Contamination in a Rural Village of Northern Lao PDR

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor.

A Survey of Helminth Infections in the Black Rat from Stara Zagora District, Bulgaria

A field study was conducted to disclose the prevalence of different helminth parasites in the black rat, Rattus rattus, in some regions of Stara Zagora district, Bulgaria. Out of 67 examined rats, 53 (79.1%) were found to be positive. Helminths of three classes were detected such as Cestoda: Hymenolepis diminuta (47.8%), Hymenolepis nana (43.3%), Taenia taeniaeformis larvae (7.5%), Taenia polyacantha larvae (1.5%); Secernentea: Syphacia obvelata (4.5%), Aspiculuris tetraptera (3.0%) and Adenophorea: Capillaria hepatica (9.0%), Trichuris muris (3.0%). Of all the investigated rats, 27 (40.3%) were infected by one helminth species and 26 (38.8%) by more than one. Hymenolepis diminuta was a predominant species in cases of single infections (23.9%). The most frequent co-infections were observed by H. nana and H. diminuta (16.4%).

Case Report: A Symptomatic Case of Hymenolepis diminuta Infection in an Urban-Dwelling Adult in Malaysia

A case of Hymenolepis diminuta infection in a 43-year-old Malaysian male with persistent abdominal colicky pain is reported. Endoscopy revealed whitish worms in the lumen of the small intestine, which were identified as H. diminuta after microscopy. Patient was successfully treated with a single dose of praziquantel (25 mg/kg).

Hymenolepis diminuta Infection in a School Going Child: First Case Report from Uttarakhand

Hymenolepis diminuta (H.diminuta) is prevalent worldwide, and a few hundred human cases have been reported till date. It is primarily a rodent parasite and humans (usually children) can act as accidental hosts. Infections are usually asymptomatic but abdominal pain, irritability, pruritis, mild diarrhoea and eosinophilia are among the existing symptoms in a few of the reported cases. Here, we report a case of an 11-year-old female child from Bijnor, who presented to us with complaints of abdominal pain, fatigue and irregular episodes of fever. Routine stool examination showed characteristic eggs of H.diminuta. Patient was given a single oral dose of praziquantel (25 mg/kg) and she improved. This case is presented to emphasize that till date there are very few reports on H.diminuta and there is limited data regarding its treatment protocols (dose and duration). Furthermore, albendazole which is commonly used drug for deworming helminthic infections is less effective in these infections.

Cardiorespiratory and gastrointestinal parasites of dogs in north-west Italy

The present study was conducted to evaluate the prevalence of gastrointestinal and cardio-respiratory parasites in dogs in Liguria (northwest Italy) which is a region that has scarcely been studied. A total of 450 dogs (260 males and 190 females) were enrolled in the study from 2009 and 2013. All dogs lived in a rural or semi-rural environment in the provinces of Imperia (n = 352) or Savona (n = 98), Liguria. Coprological examinations showed that 197 dogs (43.8 %, CI 38.7-48.9 %) were infected by parasites. Specifically, 3.3 % of the dogs presented only cardio-respiratory species, 32.4 % only intestinal species, and 8.0 % presented a mixed infection.

The most frequent intestinal parasites were Toxocara canis (20 %), Trichuris vulpis (17.8 %), Ancylostomatidae (12 %), Coccidia (2.7 %), Aonchotheca putorii (1.8 %) and Toxascaris leonina (1.8 %). The cardio-respiratory species found were Eucoleus aerophilus (9.6 %), Eucoleus boehmi (1.6 %), Angiostrongylus vasorum (0.7 %), and Crenosoma vulpis (0.2 %). A total of 116 dogs (25.8 %) were parasitized by a single species, multiple infections were observed in 81 dogs (18.0 %) up to a six-order infection.

This preliminary study highlighted that the prevalence of intestinal parasites in investigated area is high. Cardio respiratory parasites were detected in an area that has not been investigated before. The creation of a more extensive sampling programme of the area, on a provincial basis in order to build a more detailed map of prevalences for different species of dog parasites throughout Liguria, a more extensive sampling programme of the area needs to be created - ideally for each province.

Differential diagnosis and molecular characterization of Hymenolepis nana and Hymenolepis diminuta (Cestoda: Cyclophyllidea: Hymenolepididae) based on nuclear rDNA ITS2 gene marker

Given the widespread distribution and medical implication of members of the genus Hymenolepis, specific identification of the aetiological agent becomes imperative. For precise diagnosis of the species, molecular techniques such as PCR and RFLP of the nuclear ribosomal internal transcribed spacer 2 (rDNA-ITS2) gene marker were carried out. The results showed distinct restriction patterns for both Hymenolepis nana and Hymenolepis diminuta when digested with either of the enzymes RsaI, HaeIII or HhaI. The annotated rDNA-ITS2 sequences from the two species revealed differences in the length; the folded secondary structure also depicted clear demarcation between the two species with variations in length of the helices, pyrimidine-pyrimidine mismatches and sites where motifs occur. In phylogenetic analysis of the evolutionary relationship between the two species as well as with other members of the family Hymenolepididae, the species causing human hymenolepiasis were found to be distantly related as they diverged independently from the ancestral lineage.

Potentially zoonotic helminthiases of murid rodents from the Indo-Chinese peninsula: impact of habitat and the risk of human infection

In this study, we report the potential rodent-borne zoonotic helminths in wild-caught murid rodents from four categorized habitats-forest, nonflooded land, irrigated land, and human settlement in seven localities of Thailand, Cambodia, and Lao PDR. Out of 2478 rodent samples, 735 (29.7%) were infected by at least one of the following zoonotic helminth species: Echinostoma malayanum, Echinostoma ilocanum, Plagiorchis muris, Raillietina spp., Hymenolepis diminuta, Hymenolepis nana, Cyclodontostomum purivisi, and Moniliformis moniliformis. Raillietina spp. showed the highest prevalence (13.8%), followed by H. diminuta (8.6%), H. nana (6.7%), and C. purvisi (1.0%). Habitat affected the intensity of helminth infection in murid rodent hosts. Specific habitats favoring each zoonotic helminth species are discussed in relation to the risk of human infection. Season and host maturity influenced intensity of total zoonotic helminths, but there was no influence of host gender. However, in terms of individual helminth species, female rodents were more infected by E. malayanum, E. ilocanum, and C. purvisi than males. Among the rodent species, Rattus tanezumi seems to play the most important role as a reservoir by hosting seven zoonotic heminth species. This rat is ubiquitously found in all types of the habitats, suggesting that it can act as an important bridge species, carrying parasites across different habitats.

A case of Hymenolepis diminuta in a young male from Odisha

Hymenolepis diminuta also known as rat tapeworm rarely causes hymenolepiasis in humans. We report a case of H. diminuta infection in an 18-year-old male farmer who presented with intermittent pruritic maculopaular rashes and dull aching left iliac fossa pain for 6 months. Patient was cured with 2 doses of praziquantel 20 mg/kg on day 0 and 7.

FLOTAC for the diagnosis of Hymenolepis spp. infection: proof-of-concept and comparing diagnostic accuracy with other methods

Hymenolepis nana is the most common cestode parasitizing humans, yet it is under-diagnosed. We determined the optimal flotation solution (FS) for the diagnosis of this intestinal parasite with the FLOTAC method, and compared its diagnostic accuracy with an ether-concentration technique and the Kato-Katz method. Zinc sulphate (specific gravity 1.20) proved to be the best-performing FS. Using this FS, we detected 65 H. nana infections among 234 fixed fecal samples from Tajik and Sahrawi children (prevalence 27.8 %). The ether-concentration technique detected 40 infections (prevalence 17.1 %) in the same samples. Considering the combined results as a reference, the sensitivities of FLOTAC and ether-concentration were 95.6 % and 58.8 %, respectively. The Kato-Katz method resulted in a prevalence of only 8.7 %. In terms of eggs per gram of stool, a significantly (P <0.05) higher value was obtained with the FLOTAC and Kato-Katz techniques compared to ether-concentration. In another study carried out in China, the FLOTAC method detected six Hymenolepis diminuta infections in 302 fecal samples, whereas five samples were found positive with the Kato-Katz technique. We conclude that FLOTAC is an accurate coprodiagnostic technique for H. nana and H. diminuta, two species which join a growing list of intestinal parasites that can be reliably diagnosed by this technique.

The inability of tapeworm Hymenolepis diminuta and fluke Dicrocoelium dendriticum to metabolize praziquantel

Biotransformation enzymes can, to a certain extent, protect parasitic worms against the toxic effects of anthelmintics and can contribute to drug-resistance development. The objective of our work was (1) to find and identify phase I and II metabolites of the anthelmintic praziquantel (PZQ) formed by the lancet fluke (Dicrocoelium dendriticum) and the rat tapeworm (Hymenolepis diminuta) and (2) to compare PZQ metabolites in helminths with PZQ biotransformation in rat as host species. Ultra high performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) was used for this purpose. During in vitro incubations, mitochondria-like and microsomes-like fractions (prepared from homogenates of adult worms or from rat liver homogenate) were incubated with 10 and 100 μM PZQ. Liquid/liquid extraction was used for samples during in vitro experiments. In the ex vivo study, living D. dendriticum and H. diminuta adults were incubated in RPMI-1640 medium in the presence of 50 nM or 100 nM PZQ for 24h. After incubation, the worms were removed from the medium and homogenized. Homogenates of worms, medium from the incubation of worms or rat hepatocytes and rat urine (collected during 24h after oral PZQ administration) were separately extracted using solid-phase extraction. The results showed that both D. dendriticum and H. diminuta enzymatic systems are not able to metabolize PZQ. On the other hand, thirty one different phase I and four phase II PZQ metabolites were detected in rat samples using UHPLC/MS/MS analyses. These results show that our experimental helminths, as the members of tapeworm and fluke groups of parasites, are not able to deactivate PZQ, and that the biotransformation enzymes of the studied helminths do not contribute to PZQ-resistance.