A molecular phylogeny of nuclear and mitochondrial sequences in Hymenolepis nana (Cestoda) supports the existence of a cryptic species

Since isolates of Hymenolepis nana infecting humans and rodents are morphologically indistinguishable, the only way they can be reliably identified is by comparing the parasite in each host using molecular tools. In the current study, isolates of H. nana from rodent and human hosts from a broad geographical range were sequenced at the ribosomal first internal transcribed spacer (ITS1), the mitochondrial cytochrome c oxidase subunit 1 (C01) gene and the nuclear paramyosin gene loci. Twenty-three isolates of H. nana were sequenced at the ITS1 locus and this confirmed the existence of spacers which, although similar in length (approximately 646 bp), differed in their primary sequences which led to the separation of the isolates into 2 clusters when analysed phylogenetically. This sequence variation was not, however, related to the host of origin of the isolate, thus was not a marker of genetic distinction between H. nana from rodents and humans. Sequencing of a 444 bp fragment of the mitochondrial cytochrome c oxidase 1 gene (C01) in 9 isolates of H. nana from rodents and 6 from humans identified a phylogenetically supported genetic divergence of approximately 5% between some mouse and human isolates. This suggests that H. nana is a species complex, or 'cryptic' species (=morphologically identical yet genetically distinct). A small segment of the nuclear gene, paramyosin, (625 bp or 840 bp) was sequenced in 4 mouse and 3 human isolates of H. nana. However, this gene did not provide the level of heterogeneity required to distinguish between isolates from rodent and human hosts. From the results obtained from faster evolving genes, and the epidemiological evidence, we believe that the life-cycle of H. nana that exists in the north-west of Western Australia is likely to involve mainly 'human to human' transmission.

Hymenolepis nana: a common cause of paediatric diarrhoea in urban slum dwellers in India

The prevalence of intestinal parasitic infections was studied for a period of 5 years (April 1996-April 2001) among urban slum dwellers. All age groups were represented in the study. Parasitological examinations were performed on 939 faecal specimens collected on a household basis. The total prevalence of pathogenic parasites was 33.6 per cent. No significant age and sex differences in pathogenic parasites were observed. The prevalence of intestinal helminths and pathogenic protozoa was as follows: Hymenolepis nana (9.9 per cent), Ascaris lumbricoides (8.5 per cent), Giardia lamblia (8.4 per cent) and Entamoeba histolyticaldispar (3.7 per cent). Thirty-four E. histolytica/dispar positive samples were cultured and speciation was done using polymerase chain reaction (PCR). The predominant isolate was E. dispar compared to E. histolytica. The notable finding of the present study was high prevalence of Hymenolepis nana compared with other parasitic infections in slum dwellers.

Comparative clinical studies of nitazoxanide, albendazole and praziquantel in the treatment of ascariasis, trichuriasis and hymenolepiasis in children from Peru

Three randomized clinical studies were conducted in 2000 to evaluate the efficacy of nitazoxanide paediatric suspension compared to albendazole in the treatment of ascariasis and trichuriasis and praziquantel in the treatment of hymenolepiasis in children from Cajamarca, Peru. Nitazoxanide was administered at a dose of 100 mg (age 1-3 years) or 200 mg (age 4-11 years) twice daily for 3 days, albendazole as a 400-mg single dose and praziquantel as a 25-mg/kg single dose. Post-treatment parasitological examinations were carried out on 3 faecal samples, each collected on a different day between 21 and 30 days following initiation of treatment. Nitazoxanide cured 89% (25/28), 89% (16/18) and 82% (32/39) of the cases of ascariasis, trichuriasis and hymenolepiasis respectively compared with 91% (32/35), 58% (11/19) and 96% (47/49) for the comparator drugs. Each of the drugs produced egg reduction rates in excess of 98%. There were no significant adverse events or abnormalities in haematology or clinical chemistry values or urinalysis.

Tapeworm identification in the fat sand rat (Psammomys obesus obesus)

The identification of a tapeworm (Rodentolepis nana, formerly named Hymenolepis nana) infection in a research breeding colony of sand rats (Psammomys obesus obesus) was complicated because of the unexpected long length (< 150 mm) of the worms. Other morphologic features that were consistent with this identification included the number (24), size (16 mm), and shape of the hooks on the rostellum. No evidence of intermediate hosts was found in the colony. Previous surveys of natural populations of sand rats had not identified this tapeworm. However, a detailed search of the literature revealed that variation in the size of R. nana had been reported, thus supporting the final identification of the tapeworm. R. nana is important and interesting because of its zoonotic potential and because it is the only tapeworm that is able to infect its definitive host without use of an intermediate host. This report is presented to help clarify the ambiguity found in the laboratory animal literature about the differences in the size of R. nana among rodent species used in research.

Morphological and genetic differentiation of Rodentolepis straminea (Goeze, 1752) and Rodentolepis microstoma (Dujardin, 1845) (Hymenolepididae)

The two related species, Rodentolepis straminea (Goeze, 1782) and Rodentolepis microstoma (Dujardin, 1845) (Cestoda, Hymenolepididae), both parasites of rodents, were compared morphologically and electrophoretically. Adult worms were isolated from three wild rodent species of the family Muridae (Apodemus flavicollis, Apodemus sylvaticus, and Mus musculus) from three different sites in Spain and France. Although these two species were strikingly similar in morphological appearance, some of the morphological and metrical features analysed (scolex, mature segments and eggs) can be used for differentiation. Fixed allelic differences were found. Of the ten enzymes detected by starch-gel electrophoresis, six (AAT, AK, GPI, MDH, NP, PGM) showed characteristic isoenzyme profiles in each species. Only in MPI, PEPC, PEPD, and ME enzyme loci were no differences found. The study revealed that the two taxa can be clearly differentiated.

Human infection with Hymenolepis diminuta: case report from Spain

We report a case of Hymenolepis diminuta infection in a human. The patient was a 5-year-old girl referred to us through the onset of a cyanotic attack. Treatment with a single dose (10 mg/kg of body weight) of praziquantel was ineffective, but the parasite was eradicated after three treatment cycles with the same drug at dosages of 25 mg/kg/day for 5 days.

The spatial and temporal concentrations of choline in the lumen contents of the small intestine of uninfected and Hymenolepis diminuta infected rats

The spatial and temporal concentrations of free choline in the lumen of the small intestine of the uninfected and Hymenolepis diminuta-infected rat were investigated. In the unfed infected or uninfected rat, the choline concentrations ranged from approximately 500 microM in the duodenum to approximately 20 microM in the posterior ileum, with some segments in infected rats containing significantly higher choline levels than in uninfected rats. Following feeding, choline levels were significantly elevated to approximately 3 mM by 6 h, although these concentrations fell rapidly in transit down the intestine. By 12 h the choline levels were similar to those in the unfed rat. An initial small shift in the worm biomass toward the duodenum after feeding was followed by a redistribution of biomass along the length of the small intestine. The worm biomass, however, had little or no effect on the choline levels. The high concentrations of free choline observed in the anterior regions of the intestine are postulated to be predominantly determined by nutritional intake while the concentrations in the posterior region may in part be determined by blood choline levels. The high levels of choline indicate that choline is not limiting to support the growth of the worms.

[The effect of treatment on the course of invasion by Hymenolepis nana and the state of its population in white mice]

Leukinferon administered before infection affects the development of a Hymenolepis nana population in the murine intestine: in rodents, its defective forms predominate over mature ones. Leukinferon caused cell prestimulation in the immune system and activation of nonspecific defense factors. The cytokine properties of the agent appear to have an impact on parasitic growth and development by leading to formation of defective Hymenolepis forms directly and indirectly through the host's body due to the prestimulation and enhancement of nonspecific defense. There may be a concurrent influence of these factors on H. nana embryos in the murine intestine.

Application of lactophenol cotton blue for identification and preservation of intestinal parasites in faecal wet mounts

Wet mounting is the simplest and easiest technique for the examination of faeces. Routinely employed wet mounts in most of the laboratories include saline, iodine and buffered methylene blue. Lactophenol cotton blue [LCB] staining--mounting medium is commonly used for microscopic identification of fungi. LCB and its modifications were tested as staining mounting medium on parasite positive faecal samples [both fresh as well as formalin fixed] to stain and demonstrate morphology and to preserve parasitic elements [trophozoites, cysts, ova and larvae] in wet mounts. Protozoal cysts [Entamoeba histolytica and Giardia lamblia], helminthic OVA [Ancylostoma duodenale, Ascaris lumbricoides, Enterobius vermicularis, Taenia solium and Hymenolepis nana] and larvae [Strongyloides stercoralis] were well-stained and preserved their morphology in nailpolish enamel sealed LCB-faecal mounts. Morphology was better appreciated in LCB-formalin fixed faecal mounts as compared to LCB fresh faecal mounts and was well preserved by the end of twelve weeks.

[Epidemiological study on Hymenolepis nana infection in Ciego de Avila Province, Cuba]

An epidemiological study on H. nana infection was carried out in Ciego de Avila province, Cuba, from 1981 to 1995. In this 15 years period 3,108,422 stool samples were examined for parasites, H. nana eggs were found in 250 (0.008%). Seasonal influence of this parasitism was not detected. There were more cases in children than in adults, with males prevailing over females. The more frequent symptoms and signs were abdominal pain, diarrhea and anorexia which relationships with food habits, dwelling characteristics, children day care center and school orchards are analyzed.

Prevalence of intestinal parasites in rural Southern Indians

OBJECTIVE

To determine the prevalence of intestinal protozoal and helminthic infection in a rural population.

METHOD

Seventy-eight members of 15 families from a village were studied. Stool samples from all subjects were examined on alternate days for one month.

RESULTS

The overall prevalence rate of various parasitic infections was 97.4%, with only 2 of 78 subjects not excreting parasites in any of their 15 samples. Eighteen (23.1%) persons had only one type of parasite, while 58 (74.3%) excreted multiple parasites. Giardia and Cryptosporidium were the commonest protozoan infections, affecting 42/78 (53.8%) and 31/78 (39.7%), respectively. Hookworm infestations were the commonest helminthic infections, seen in 48/78 (61.5%). Based on excretion patterns, the asymptomatic individuals could be divided into 2 groups of infrequent and frequent excretors, indicating that the host response may determine the level of parasite replication in the gut.

[Helminth fauna of the red fox (Vulpes vulpes LINNE 1758) in south Sachsen-Anhalt--1: Cestodes]

Between January 1993 and November 1994 a total of 1300 red foxes from the administrative districts Halle and Dessau were examined for the presence of Echinococcus multilocularis and other cestodes. Echinococcus multilocularis-infections were detected in only 4 of 1300 (0.3%) foxes. Furthermore the following cestodes were found: Mesocestoides spp. (54.1%), Taenia crassiceps (17.7%), Taenia polyacantha (11.9%), Hydatigera taeniaeformis (0.2%), Taenia serialis (0.15%), Taenia pisiformis (0.15%), not determinable taeniids (9.2%), Dipylidium caninum (0.2%) and Hymenolepis spp. (0.08%).

Interactions between rat C-reactive protein and adult Hymenolepis diminuta

Interactions between adult Hymenolepis diminuta and rat C-reactive protein (CRP) were investigated in vivo and in vitro. Using an ELISA technique, serum levels of CRP were monitored in rats infected with 100 cysticercoids. Although infection increased the level of this protein in the early stages of parasitization, the increase was not significant until 35 days post-infection (p.i.). Secondary infections did not enhance the response. When H. diminuta was cultured in the presence of CRP, reduced worm motility and opaque areas were observed and electron microscopical studies revealed shedding of microtriches and lysis of the tegument. Initially, damage was restricted to the strobila which correlated with the regional distribution of phosphorylcholine as visualized using immunofluorescence.

Cytokine production during infection with Hymenolepis diminuta in BALB/c mice

Levels of the cytokines IFN-gamma, IL-2, IL-3, IL-4 and IL-5 were monitored in cells from the mesenteric lymph nodes (MLN) of BALB/c mice infected with Hymenolepis diminuta after stimulation in vitro with Con-A. Infection was associated with an increased production of IL-3, IL-4 and IL-5 and a low production of IFN-gamma, indicating the preferential activation of a Th2 response. It is suggested that this reflects the purely lumenal development of this worm. The results are discussed in relation to effector mechanisms known to be involved in immunity to intestinal helminths.

Detection of gastrointestinal nematodes by a coproantigen capture ELISA

An assay is described for the quantitative detection of excretory/secretory antigens liberated by the intestinal nematode Heligmosomoides polygyrus and voided in the host's faeces. A rabbit polyclonal antiserum to the antigens detected them in a dose-dependent manner and was sufficiently sensitive to recognise infection in mice carrying a mean worm burden of nine worms. The assay was specific, giving higher optical density readings with the faeces of mice infected with H polygyrus than with faeces from mice carrying patent infections with Trichuris muris, Hymenolepsis microstoma or the intestinal phase of Trichinella spiralis, or with faeces from rats carrying Hymenolepis diminuta or hamsters carrying Necator americanus or Ancylostoma ceylanicum. It detected the parasite antigens in faeces stored for eight weeks at -20, 4 or 20 degrees C and could detect prepatent infections. The assay has potential for the development of infection intensity-sensitive assays for gastrointestinal nematodes and for the detection of animals harbouring the arrested larvae of parasites.

The minimum effective dose of praziquantel in treatment of Hymenolepis diminuta in rats

To determine the minimum effective dose of praziquantel against Hymenolepis diminuta in rats, 5.0 mg/kg, 2.5 mg/kg, 1.0 mg/kg, 0.5 mg/kg, 0.1 mg/kg, or 0.05 mg/kg praziquantel were given to each of five experimentally infected rats in six groups. Faecal samples from each rat were examined on ten consecutive days following treatment. The rats were killed and examined for worms on day 10. Based on the results of faecal examination and autopsy, the minimum effective dose of praziquantel against Hymenolepis diminuta in rats was determined to be 0.5 mg/kg.

The morphology of hymenolepidid and dilepidid cestodes from common and pygmy shrews (Soricidae) in southeast England

One hundred and six of 109 common shrews (Sorex araneus) and 62 of 72 pygmy shrews (S. minutus), obtained by Longworth trapping in Southeast England, were infected with cestodes. Ten species were recovered: Choanotaenia hepatica and Hymenolepis prolifer (found in S. araneus); Choanotaenia crassiscolex, Hymenolepis furcata, H. jacutensis, H. schaldybini, H. scutigera, H. singularis, H. diaphana and H. infirma (in both hosts). The morphology, taxonomy and ecology of these species are discussed and the findings of the present study are discussed with reference to previous studies of the helminth fauna of British shrews. Cysticercoids of C. crassiscolex were found in the snail, Vitrina pellucida, and cysticercoids of H. schaldybini in the staphylinid beetle, Anthobium unicolor.

[A coprological study of intestinal infections in Northern Morocco (provinces of Tangier, Tetuán and Larache)]

BACKGROUND

An epidemiological study on intestinal parasites has been carried out in Northern Morocco (province of Tangier, Tetuan and Larache). A comparative Study has been made at a provincial, city and areas (urban and rural) level. Also the SPI (simple parasitism index) and the CPI (comparative parasitism index) distribution.

METHODS

The coprological method used were: direct, concentration (Fulleborn, Telemann and Kato) method and ye test technics (Ferric Hematoxylin and E. Chlorazol Black).

RESULTS

The number of faecal samples were 4643, parasitism people 2637 and the total number of parasites were 4816. SPI 56.79% and CPI 1.83. Among the Protozoa, Entamoeba coli, followed by Endolimax nana, Giardia lamblia and Iodamoeba buetschlii prevailed, the other species coming a lung distance behind. Among the Helminths, Trichuris trichiura prevailed much more than the others; Ascaris lumbricoides followed and on the third place were Enterobius vermicularis and Hymenolepis nana. The percentage found for E. vermicularis was very high, since an appropriate technique of diagnosis was not used. The data have been statistically tested.

CONCLUSIONS

We found a high rate of parasitism in the 3 provinces that have studied and an approximate number of two parasites per person. SPI and CPI are greater in Tetuan and Larache than in Tangier.

Specific cross-immunity between Hymenolepis nana and H. diminuta: effects of transfer of immunity with homologous and heterologous immune mesenteric lymph node cells in BALB/c mice

In BALB/c mice, Hymenolepis nana and H. diminuta stimulate a strong response. Accelerated expulsion of adult worms, as well as protection against larvae, occurred anamnestically when homologous or heterologous mesenteric lymph node cells from immune mice were transferred before challenge. The results further support the hypothesis that worm expulsion is a thymus dependent phenomenon. The extensive cross reactivity found is discussed in relation to the distinctive characteristics of the two worms. These results strongly suggest that there are antigenic similarities between the two parasites and that the accelerated expulsion of heterologous challenge infections is the result of a specific response to shared antigens.