Zoonotic Helminthiases in Rodents (Bandicota indica, Bandicota savilei, and Leopoldamys edwardsi) from Vientiane Capital, Lao PDR.

Zoonotic helminths of three rodent species, Bandicota indiaca, Bandicota savilei, and Leopoldamys edwardsi, were investigated in Vientiane capital, Lao PDR. A total of 310 rodents were infected with 11 species of helminth parasites. There were 168 (54.2%) of 310 rodents infected with zoonotic helminths. From our results, there are six recorded zoonotic helminth species, and the highest prevalence was exhibited by Raillietina sp. (30.7%), followed by Hymenolepis diminuta (17.7%), Hymenolepis nana (2.6%), Echinostoma ilocanum (1.9%), Echinostoma malayanum (1.3%), and Angiostrongylus cantonensis (1%). This is the first study of zoonotic helminths in L. edwardsi and the first report of H. diminuta, H. nana, E. ilocanum, and E. malayanum in Bandicota indica and B. savilei, and the first demonstration of A. cantonenensis in B. indica in Lao PDR. From our results, these three rodents are potentially important reservoir hosts of zoonotic helminths. Thus, effective control programs should be considered for implementation to prevent the transmission of these zoonoses in this area.

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.

Epidemiological Survey on Schistosomiasis and Intestinal Helminthiasis among Village Residents of the Rural River Basin Area in White Nile State, Sudan.

There have been some reports on schistosomiasis of school children in Sudan's Nile River basin area; however, information about the infection status of Schistosoma species and intestinal helminths among village residents of this area is very limited. Urine and stool samples were collected from the 1,138 residents of the Al Hidaib and Khour Ajwal villages of White Nile State, Sudan in 2014. The prevalence of overall schistosomiasis and intestinal helminthiasis was 36.3% and 7.7%, respectively. Egg positive rates were 35.6% for Schistosoma haematobium, 2.6% for S. mansoni, and 1.4% were mixed. The prevalence of schistosomiasis was significantly higher in men (45.6%) than in women (32.0%), in Khou Ajwal villagers (39.4%) than in Al Hidaib villagers (19.2%), and for age groups ≤15 years old (51.5%) than for age groups >15 years old (13.2%). The average number of eggs per 10 ml urine (EP10) of S. haematobium infections was 18.9, with 22.2 eggs in men vs 17.0 in women and 20.4 in Khou Ajwal villagers vs 8.1 in Al Hidaib villagers. In addition to S. mansoni eggs, 4 different species of intestinal helminths were found in the stool, including Hymenolepis nana (6.6%) and H. diminuta (1.0%). Collectively, urinary schistosomiasis is still prevalent among village residents in Sudan's White Nile River basin and was especially high in men, children ≤15 years, and in the village without a clean water system. H. nana was the most frequently detected intestinal helminths in the 2 villages.

Intestinal immunity suppresses carrying capacity of rats for the model tapeworm, Hymenolepis diminuta.

Hymenolepis diminuta is a parasitic tapeworm of the rat small intestine and is recognized as a useful model for the analysis of cestode-host interactions. In this study, we analyzed factors affecting the biomass of the tapeworm through use of rat strains carrying genetic mutations, namely X-linked severe combined immunodeficiency (xscid; T, B and NK cells deficiency), nude (rnu; T cell deficiency), and mast cell deficient rats. The worm biomass of F344-xscid rats after infection with 5 cysticercoids was much larger than control F344 rats from 3 to 8 weeks. The biomass of F344-rnu rats was also larger than the controls, but was intermediate between F344-xscid and control rats. These observations demonstrated that host immunity can control the maximal tapeworm biomass, i.e., carrying capacity, of the rat small intestine. Both T cell and other immune cells (B and NK cells) have roles in determining the carrying capacity of tapeworms. Total worm biomass and worm numbers in mast cell deficient rats (WsRC-Ws/Ws) were not significantly different from control WsRC-+/+ rats after 3 and 6 weeks of primary infection. Mast cell deficient rats displayed reinfection resistance for worm biomass but not worm expulsion. These findings suggest that the mast cell has a role for controlling the biomass of this tapeworm in reinfection alone, but does not affect the rate of worm expulsion. Overall, our findings indicate that the mast cell is not a major effector cell for the control of the carrying capacity of tapeworms. The identity of the major effector cell remains unknown.

Young mice expel the tapeworm Hymenolepis diminuta and are protected from colitis by triggering a memory response with worm antigen.

Infection with helminth parasites reduces the severity of concomitant inflammatory disease in adult mice. There is an alarming increase of inflammatory bowel disease (IBD) in children. It is important to determine whether helminth therapy would be of value in pediatric IBD and whether triggering immunological memory to the worm would be anticolitic. Three-week-old (young) and eight-week-old (adult) Balb/c mice were infected with H. diminuta, and infectivity and T helper 2 (Th2) immunity were assessed. Other mice received H. diminuta with or without a crude worm extract ( HdE) 28-42 days postinfection (dpi) with or without dinitrobenzene sulphonic acid [DNBS, 1.5 mg (young) or 3 mg (adults), ir], and colitis was assessed 72 h later. Infected young mice developed Th2 immunity and expelled H. diminuta; expulsion was delayed by ~2 days compared with adult mice. Colitis, as gauged by macroscopic disease and histopathology scores, was less severe in young mice infected 10 days, but not 8 days, before DNBS. Protection against DNBS-induced colitis was accompanied by an increased capacity to make interleukin (IL)-4 and IL-10. Mice infected with H. diminuta were not protected from DNBS-colitis when challenged 28 days later; however, injection of these mice with HdE coincident with DNBS resulted in less disease and increased splenic IL-4 and IL-10. Using a boost (500 µg HdE, 28 dpi) and repeat HdE (100 µg, 42 dpi) regimen with infected mice suppressed DNBS-colitis, as did adoptive transfer of splenic CD4+ T cells from infected mice with low-dose HdE challenge. Should these data translate to IBD, then helminth therapy could be of value in pediatric-onset IBD, and defining the antigen(s) that elicit antihelminth immunological memory could serve as an anticolitic approach in previously infected individuals. NEW & NOTEWORTHY This study demonstrates that juvenile mice are protected from colitis by infection with the tapeworm Hymenolepis diminuta and that using worm antigen to trigger an immunological memory response in previously infected mice can be used to limit the severity of colitis.

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).

Prevalence of Hymenolepis nana and H. diminuta from Brown Rats (Rattus norvegicus) in Heilongjiang Province, China.

Hymenolepis nana and Hymenolepis diminuta are globally widespread zoonotic cestodes. Rodents are the main reservoir host of these cestodes. Brown rats (Rattus norvegicus) are the best known and most common rats, and usually live wherever humans live, especially in less than desirable hygiene conditions. Due to the little information of the 2 hymenolepidid species in brown rats in China, the aim of this study was to understand the prevalence and genetic characterization of H. nana and H. diminuta in brown rats in Heilongjiang Province, China. Total 114 fecal samples were collected from brown rats in Heilongjiang Province. All the samples were subjected to morphological examinations by microscopy and genetic analysis by PCR amplification of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene and the internal transcribed spacer 2 (ITS2) region of the nuclear ribosomal RNA gene. In total, 6.1% (7/114) and 14.9% (17/114) of samples were positive for H. nana and H. diminuta, respectively. Among them, 7 and 3 H. nana isolates were successfully amplified and sequenced at the COX1 and ITS2 loci, respectively. No nucleotide variations were found among H. nana isolates at either of the 2 loci. Seventeen H. diminuta isolates produced 2 different COX1 sequences while 7 ITS2 sequences obtained were identical to each other. The present results of H. nana and H. diminuta infections in brown rats implied the risk of zoonotic transmission of hymenolepiasis in China. These molecular data will be helpful to deeply study intra-specific variations within Hymenolepis cestodes in the future.

A survey of zoonotic pathogens carried by house mouse and black rat populations in Yucatan, Mexico.

The house mouse (Mus musculus) and the black rat (Rattus rattus) are reservoir hosts for zoonotic pathogens, several of which cause neglected tropical diseases (NTDs). Studies of the prevalence of these NTD-causing zoonotic pathogens, in house mice and black rats from tropical residential areas are scarce. Three hundred and two house mice and 161 black rats were trapped in 2013 from two urban neighbourhoods and a rural village in Yucatan, Mexico, and subsequently tested for Trypanosoma cruzi, Hymenolepis diminuta and Leptospira interrogans. Using the polymerase chain reaction we detected T. cruzi DNA in the hearts of 4·9% (8/165) and 6·2% (7/113) of house mice and black rats, respectively. We applied the sedimentation technique to detect eggs of H. diminuta in 0·5% (1/182) and 14·2% (15/106) of house mice and black rats, respectively. Through the immunofluorescent imprint method, L. interrogans was identified in 0·9% (1/106) of rat kidney impressions. Our results suggest that the black rat could be an important reservoir for T. cruzi and H. diminuta in the studied sites. Further studies examining seasonal and geographical patterns could increase our knowledge on the epidemiology of these pathogens in Mexico and the risk to public health posed by rodents.

Rehydration methods to recover cysticercoids of the rat tapeworm Hymenolepis diminuta from dry flour beetle carcasses.

Terrestrial arthropods host a variety of helminth parasites, yet quantifying the intensity of infection in these hosts post-mortem is challenging because carcasses may desiccate quickly. We recovered cysticercoids of Hymenolepis diminuta from desiccated flour beetle (Tribolium confusum) carcasses by modifying a published insect rehydration procedure. Without rehydration, carcasses dissected more than 1 day post-mortem had noticeable degradation of cysticercoids. Mild rehydration (soaking in water only for 2 days, or 0.5-10% KOH for 1 h followed by 1 day in water, or 0.5% KOH for 1 day) left carcasses tough and time-consuming to dissect, but all parasites could be recovered and were similar in body size to fresh cysticercoids. Moderate rehydration (5-10% KOH for 1 day) allowed all parasites to be recovered and facilitated dissection by partially dissolving internal organs of the beetle while causing little degradation of the cysticercoids. Harsh rehydration (5-10% KOH for 1 day followed by 5 days in water) not only dissolved internal beetle tissues but also severely damaged cysticercoids, such that parasite counts were unreliable. The degree of initial carcass desiccation had little effect on results following rehydration. However, regardless of treatment used, intact cercomers were rarely retained on rehydrated cysticercoids. Rehydration was less successful on early developmental stages of the parasite, which were recovered reliably only as they neared the cysticercoid stage. This method has utility for studies of parasite-induced mortality by permitting accurate and reliable parasite counts from dead, desiccated hosts.

[A rare case of Hymenolepis diminuta infection in a small child]. / Nadir bir olgu olarak küçük bir çocukta Hymenolepis diminuta enfeksiyonu.

Unlike Hymenolepis nana that transmits directly from person to person, the transmission of Hymenolepis diminuta to human is via accidentally ingesting of arthropods carrying cysticercoid larvae as intermediate host. In places with poor hygienic conditions, this cestod may cause seldom infections especially in children. Studies carried out on various populations have reported the prevalence rate of H.diminuta between 0.001% and 5.5%. Although the reported cases are mostly children, the disease can be seen in every age group. In this report, a pediatric case of H.diminuta infection is presented. A twenty one-month-old male patient with the symptoms of vomiting 3-4 times a day along with mud-like diarrhea continuing for a week was admitted to the pediatric outpatient clinic. According to the history, it was learned that the house where he lived was above a barn and there was a history of insect swallowing. Laboratory findings revealed iron-deficiency anemia. The macroscopic appearance of the stool was in a pale clay-like form, and by direct microscopic examination with lugol solution, 70-75 µm in diameter, thick-shelled and six central hookleted eggs that are characteristic for H.diminuta were identified. A six-day course of oral niclosamide was administered to the patient beginning with 500 mg on the first day and 250 mg on the following five days, together with the treatment for the iron deficiency anemia. After fifteen days, the oral niclosamide treatment was repeated. No H.diminuta eggs were detected in the parasitological examination performed one month after completion of the second round of treatment. This case has been presented to call attention to the importance of patient anamnesis and microscopic examination in the diagnosis of H.diminuta infection which is a rarely seen parasitosis.

Analysis of a child infected with Hymenolepis diminuta in Poland.

Hymenolepis diminuta is a cosmopolitan parasite of rats and mice which is very rare in humans. This study presents the case of a 3-year-old boy infected with Hymenolepis diminuta in Poland. The diagnosis was based on eggs found and their morphology in the patient's stool.

A case report of Hymenolepis diminuta infection in a Malaysian child.

We report a case of Hymenolepis diminuta infection in a 2-year-old Malaysian child. This case was initially reported as 'normal' after the examination of proglottids shed from the anus of the child at a private laboratory on two occasions. The putative proglottids shed was then referred to the Parasite Southeast Asia Diagnostic (Para:SEAD) Laboratory, Department of Parasitology, Faculty of Medicine, University of Malaya for further examination. Microscopic examination confirmed that the child was infected with H. diminuta based on the characteristic eggs found in the proglottids. She was treated with a single dose praziquantel (20 mg/kg of body weight) and recovered well.

In vivo anthelmintic activity of Clerodendrum colebrookianum Walp., a traditionally used taenicidal plant in Northeast India.

Although there are several effective drugs available for the treatment of intestinal helminths, the fact remains that they continue to remain out of reach to a vast majority of people in the world, especially in developing countries. On the other hand, there are a great many herbal remedies that are effective against common intestinal worms and are easily available to common people in developing countries. Clerodendrum colebrookianum Walp. (Lamiaceae) is a perennial shrub which is native to South and Southeast Asia. Traditionally, the leaves of this plant are used by the indigenous people of Northeast India as a remedy for the treatment of intestinal tapeworm infections. The aim of this study was to evaluate and authenticate the anthelmintic efficacy of C. colebrookianum leaf extract in experimentally induced Hymenolepis diminuta (a zoonotic tapeworm) infections in Wistar rats. The efficacy of the plant extract was assessed by monitoring the eggs per gram of faeces (EPG) counts and worm recovery rates of experimental animals, following treatment with the leaf extract of this plant at three different doses, i.e. 200, 400 and 800 mg/kg body weight, each given singly for 5 days. The results obtained revealed that the leaf extract of C. colebrookianum possesses a dose-dependent efficacy against the larval, immature and adult stages of H. diminuta. However, the efficacy of the extract was found to be considerably high only against the adult stages of the parasite. For this stage, a single 800-mg/kg dose of extract, given for 5 days, resulted into 68.42% reduction in the EPG counts and 62.50% reduction in the worm counts in the extract-treated group of animals, as compared to the control. The reference drug, praziquantel (5 mg/kg, single dose), however, showed slightly better efficacy and caused 95.16 and 87.00% reductions in the EPG and worm counts of treated animals, respectively. Unlike the adult stages, the efficacy of the plant extract was recorded to be comparatively low against the larval and immature stages of the parasite, as the treatment of animals with the highest dose of extract (800 mg/kg) could cause only 37.50 and 54.00% reductions in worm counts, respectively. The experimental evidence obtained in this study suggests that leaves of C. colebrookianum possess significant anthelminthic properties and supports their use against intestinal tapeworm infections in traditional medicine.

[Helminths of some laboratory animals detected by necropsy and fecal examination]. / Bazi Laboratuvar Hayvanlarinda Nekropsi ve Diski Bakisi ile Saptanan Helmintler.

A study was performed in order to determine helminths of laboratory animals. Fecal specimens obtained from 110 mice, 263 rats and 65 rabbits were investigated and 37 rats and 7 rabbits were necropsied. In general, 83.8% rats were found to be infected by necropsy, while 100% of mice,and 81.8% of rats were found to be infected with one or more helminths species by fecal examination. No rabbits were found to be infected by necropsy or fecal examination. In fecal examination of mice and rats, the prevalence of helminths was detected as follows: Syphacia muris, 100%; Aspicularis tetraptera, 53.6%; Syphacia obvelata, 46.4%; and Hymenolepis diminuta 17.9% in mice. The prevalence in rats was H. Diminuta, 62.5%; S. muris, 25%; Hymenolepis nana, 6.8%; and Trichosomoides crassicauda, 6.8%. In necropsy, S. muris was identified in all of infected rats, but only one was infected with A. tetraptera.

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

We report a case of Hymenolepis diminuta infection in a 2-year-old child living in a suburban area of Catania, Italy. This case was initially referred to us as Dipylidium caninum infection, which was not cured after being treated twice with mebendazole. However, by analyzing the clinical presentation and stool samples we arrived to the diagnosis of H. diminuta infection. The case presented with atypical allergic manifestations which had never been reported as clinical features of symptomatic H. diminuta infection; remittent fever with abdominal pain, diffuse cutaneous itching, transient thoracic rash, and arthromyalgias. The patient was treated with a 7-day cycle of oral niclosamide, which proved to be safe and effective. This case report emphasizes that a correct parasitological diagnosis requires adequate district laboratories and trained personnel. In addition, we recommend the importance of reporting all H. diminuta infection cases, in order to improve knowledge on epidemiology, clinical presentation, and treatment protocols.

Hymenolepis diminuta in a child from rural area.

We report a rare case of Hymenolepis diminuta infection in a 12-year-old girl from a rural area of Devghar.