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Overview of hymenolepis diminuta infection among Thai patients.

CONTEXT: Hymenolepis diminuta infection is a very rare cestode infection. Until present, fewer than 500 cases have been observed worldwide. OBJECTIVE: The author performed a literature review on the reports of H diminuta in Thailand in order to summarize the characteristics of this infection among Thai patients. DESIGN: This study was designed as a descriptive retrospective study. A literature review of the papers concerning H diminuta infections in Thailand was performed. RESULTS: According to this study, there have been at least 6 reports in the literature of 10 individual cases of H diminuta infection, of which 1 case was lethal. Of 4 cases that documented patients' age, the ages ranged from 20 months to 55 years. Of 5 cases that documented patients' sex, 3 were males and 2 were females. Most (9/10) were asymptomatic; however, there was 1 inpatient case, concomitant with metastatic cholangiocarcinoma. Antiparasitic drugs were prescribed in 3 cases: niclosamide in 2 cases and praziquantel in 1 case. The 2 patients receiving niclosamide passed the parasites after treatment. CONCLUSION: In conclusion, the H diminuta infection is a rare cestode infection that is sporadically reported in Thailand. The diagnosis of H diminuta infection is usually by accident during a field survey. The prognosis outcome is usually good, and the treatment does not appear to affect outcome, as there is good survival without treatment.

Female↗

Detection of serum antibodies in human Hymenolepis infection by enzyme immunoassay.

Although hymenolepiasis is the commonest cestode infection of man, there are no data available on the human immune response to this parasite. Thus, in order to determine if infection induces antibodies against Hymenolepis nana antigens, sera from 52 infected children were initially studied on Ouchterlony plates and then by enzyme-linked immunosorbent assay (ELISA), using a crude antigenic extract prepared from scolex and neck regions of adult worms. In addition, sera from persons with cysticercosis, taeniasis and other parasitoses, and normal human sera, were studied. Only one serum from the Hymenolepis group showed precipitin antibodies against H. nana antigen, while several were positive by ELISA. The sensitivity of the ELISA was 84.62% and its specificity was 100%. Very high cross-reactivity rates were obtained with taeniasis (70.6%) and cysticercosis (75%) sera. These results show that Hymenolepis infection in man induces a low but detectable humoral immune response. Although not useful for diagnostic purposes, this may be relevant to the serodiagnosis of other tissue cestode infections of man, since antibodies detected in serological tests used for the diagnosis of cysticercosis, and probably hydatidosis, could be induced by H. nana instead of Taenia solium or Echinococcus larvae.

Adolescent↗

Cestode vaccines.

Studies over the past 20 years have clearly shown the potential for developing vaccines against larval cestode infections of man and animals. The important larval cestode infections of man (Echinococcus granulosus--hydatidosis: Taenia solium--cysticercosis) involve domesticated animals as intermediate hosts in their natural life-cycles. These animals develop strong immunity against reinfection, and immunity can be artificially induced by vaccination with oncosphere antigens. A major stumbling block in developing commercial vaccines against cestodes has been the difficulty in obtaining adequate supplies of these antigens. Recent studies with Taenia ovis, a larval cestode causing cysticercosis in sheep, have demonstrated the feasibility of developing commercial vaccines against cestodes using recombinant DNA technology. A cDNA library prepared using mRNA obtained from T. ovis oncospheres was used to isolate a clone which expressed T. ovis polypeptide antigen 45W as a fusion protein with Schistosoma japonicum glutathione S-transferase (GST-45W). GST-45W gave up to 94% protection against challenge infection when used to vaccinate sheep with saponin as adjuvant. The vaccine antigen was shown by SDS PAGE to be unstable, a major disadvantage in subsequent attempts to obtain high yields of antigen for commercial production. The fusion protein has now been stabilized by reducing the size of GST-45W cDNA through deleting 19 carboxyl terminal hydropathic acids, and the resultant fusion protein GST-45W (B/X) was highly host-protective. Another experiment showed that the 45W T. ovis polypeptide cleaved enzymatically from GST-45W was still host-protective, suggesting that GST had no influence on the immunogenicity of GST-45W fusion protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Polycystic echinococcosis in Colombia: the larval cestodes in infected rodents.

Described are the characteristics of the polycystic larval cestodes found in an endemic area of echinococcosis in the Easter Plains of Colombia and the tissue reaction evoked in infected rodents. Of 848 free-ranging animals examined, polycystic hydatids were found in 44/93 Cuniculus paca and 1/369 Proechimys sp. None of 20 Dasyprocta fuliginosa examined was infected, but hunters provided a heart with hydatid cysts and information about two additional animals with infected livers. Recognition of an endemic area of polycystic echinococcosis provides a means to investigate the life cycle of the parasites and to study the histogenesis of the larval cestodes in susceptible laboratory animals.

Animals↗

A case of Diphyllobothrium nihonkaiense infection successfully treated by oral administration of Gastrografin.

A diphyllobothriid cestode infection found in a 54-year-old male residing in Oita, Japan, was successfully treated by oral administration of Gastrografin in combination with a intramuscular injection of Vagostigmin. The strobila expelled was 6.14 m long with a scolex, and morphologically identical with Diphyllobothrium nihonkaiense except unusual ovaries of which posterior horns were confluent in each proglottid. This is the first case of treatment of cestode infection by oral administration of Gastrografin.

Administration, Oral↗

Anthelmintics. A comparative review of their clinical pharmacology.

Virtually all the important helminth infections in humans can be treated with one of 5 anthelmintics currently in use: albendazole, mebendazole, diethylcarbamazine, ivermectin and praziquantel. These drugs are vital not only for the treatment of individual infections, but also useful in controlling transmission of the more common infections. This article reviews briefly the pharmacology of these 5 drugs, and then discusses current issues in the use of anthelmintics in the treatment and/or control of soil-transmitted nematode infections, filariasis, onchocerciasis, schistosomiasis (and other trematode infections), neurocysticercosis and hydatidosis. Mebendazole and albendazole are most effective against intestinal nematodes, but are contraindicated during the first trimester of pregnancy. The efficacy of prolonged therapy with these 2 drugs for treatment of larval cestode infections has not yet been established. Diethylcarbamazine is widely used to treat and control lymphatic filariasis, but adverse effects related to death of microfilariae or damage to adult worms may be marked. While ivermectin has been used in the treatment of patients with onchocerciasis, it is also undergoing investigation against lymphatic filariae. Praziquantel, used to treat schistosome infections, is also effective in other trematode infections and adult cestode infections.

Anthelmintics↗

Cysticercosis: cellular immune responses during primary and secondary infection.

Immune reactions to cysticercosis have been extensively studied in mice. The lack of significant lymphocyte infiltration into the livers of infected mice and the obvious role of antibodies in rejection has led to the general conclusion that cellular reactions do not play a role in protection against this disease. In contrast, the present study examining the immune response to cestode infections in a large animal model (sheep) revealed the presence of a massive and highly organized cellular infiltration in the livers after a secondary Taenia hydatigena infection. The majority of the infiltrating lymphocytes were of the CD4+ phenotype with much fewer CD8+ cells present. While most gamma delta-TCR+ cells in peripheral blood are SBU-T19+, the majority of gamma delta-TCR+ lymphocytes in the liver lesions are SBU-T19- suggesting selective migration of these cells into the lesions. In contrast to the diffuse distribution of T cells in the lesions, B cells were present as distinct aggregates. In primary T. hydatigena infections, host class I and class II MHC antigens were shown, for the first time in cestode infections, to be absorbed onto the surface of the metacestode bladderwall indicating their possible involvement in parasite survival. No immune reactions were observed close to the parasite although lymphocytes and eosinophils were infiltrating the adjacent portal tract areas. Most lymphocytes in both primary and secondary infections were positive for MHC class II antigens suggesting selective recruitment of activated cells to the site of infection. Significant changes in relative and absolute numbers of lymphocyte subpopulations were also observed in the draining hepatic lymph nodes dominated by a massive increase of B cells. In contrast, at the peak of local cellular infiltration, no changes in lymphocyte subpopulations were observed in peripheral blood showing the limited usefulness of this compartment in studying cellular changes in localized infections. The vigorous cellular response observed in the livers of sheep contrasts sharply with the lack of lymphocyte infiltration reported in mice indicating that small animal models may not be appropriate to study cellular responses to cysticercosis in large animals and man.

Animals↗

Enzyme-linked immunoelectrotransfer blot test for diagnosis of human hydatid disease.

Sera from 71 patients with surgically confirmed hydatid disease (which is caused by Echinococcus granulosus) were studied by an enzyme-linked immunoelectrotransfer blot (EITB) assay. Sera from patients either with other cestode infections or with another illness were used as controls. Results of the EITB test for hydatidosis were compared with those of the double-diffusion (DD5) test and an enzyme-linked immunosorbent assay (ELISA). In the EITB assay with bovine lyophilized hydatid fluid, three antigen bands of 8, 16, and 21 kDa were diagnostically important. The sensitivity of the assay by using these antigen bands was 80% for hepatic cysts, 56% for pulmonary cysts, and 56% for cysts located in multiple organs. In sera from controls, the specificity of the EITB assay was 100%. Cross-reactions to the 8-, 16-, and 21-kDa bands occurred, respectively, in 12, 4, and 4% of sera from patients with cysticercosis. No cross-reactions were noted in patients infected with Hymenolepis nana. The ELISA in which swine hydatid fluid was used as the antigen was as sensitive as the EITB test but was less specific (80%) and frequently cross-reacted with sera from patients with other cestode infections. The sensitivity of the DD5 test, which uses sheep hydatid fluid, was low (47%) , but its specificity was as high as that of the EITB assay. However, in patients with cysticercosis, cross-reactions were observed in 23% of sera tested. Despite the higher sensitivity found with the EITB assay, 23% (n = 5) of the serum samples that were positive by the DD5 test were not detected by the EITB assay. The EITB assay offers greater sensitivity and specificity than do the ELISA and the DD5 test. The highest proportion of hydatid cases is detected when the EITB and DD5 tests are run simultaneously.

Antigens, Helminth↗

Drugs five years later: praziquantel.

PURPOSE: To identify advances in knowledge of the pharmacokinetics, mechanism of action, clinical use, and side effects of the antihelminthic drug praziquantel in the 5 years since its introduction in the United States. DATA IDENTIFICATION: Studies reported from 1983 to July 1988 were identified by computer searches of MEDLINE and TOXLINE, and review of textbooks and review articles. STUDY SELECTION: Of 57 articles originally identified, 39 were selected by two readers. DATA EXTRACTION: Study quality and significance were independently assessed by each reader. RESULTS OF DATA ANALYSIS: The pharmacokinetics and clinical efficacy of praziquantel have been well documented. Yet, despite extensive in vivo and in vitro laboratory studies, the drug's mechanism of action in killing parasites is unknown. Although the efficacy of praziquantel was first established for treating schistosomiasis, in the last 5 years its clinical use has been expanded to the treatment of intestinal, tissue, and lung flukes, and intestinal and tissue cestode infections, including neurocysticercosis. The introduction of praziquantel was a significant advance in antihelminthic therapy, in that it was effective therapy for several parasites that had been previously considered untreatable. Availability of a safe, effective broad-spectrum oral antihelminthic agent consolidated the central role of chemotherapy in population-based control of many trematode and cestode parasites. Randomized trials have shown, however, that older, cheaper agents may be more cost-effective in controlling Schistosoma mansoni and Schistosoma haematobium in some endemic areas. CONCLUSIONS: Although praziquantel is the treatment of choice for most human trematode and cestode infections, cost factors have limited its use in developing countries.

Animals↗

Serological diagnosis and post-operative surveillance of human hydatid disease. II. The enzyme-linked immunosorbent assay (ELISA) using various antigens.

The ELISA using a urease conjugated antibody and 3 antigen preparations was examined for sensitivity and specificity in hydatid diagnosis. Four groups of sera tested were: 80 samples from patients with confirmed hydatid infection; 51 latex agglutination test (LA) +ve and immunoelectrophoresis test (IEP) -ve sera from patients with miscellaneous symptoms or disorders other than hydatid disease; 195 'normal' sera from healthy donors; 115 sera from persons infected with other parasites. Antigens tested included crude sheep hydatid cyst fluid (CSHCF), CSHCF partially purified by salt fractionation (PPSHCF) and CSHCF purified by sequential affinity chromatography depletion with rabbit anti-sheep IgG, 3EgH 29-2 anti-Echinococcus monoclonal antibody and 'normal' sheep Ig (ADSHCF). All 3 antigens showed high sensitivity in detecting antibody in serum from hydatid-infected patients, and gave excellent discrimination between these samples and the LA +ve IEP -ve sera and the 'normal' sera. Cross-reactions occurred with antibodies in the sera of patients with other parasitic infections, especially other larval cestodes and filarial parasites. Superior specificity was achieved with both CSHCF and ADSHCF, and ADSHCF reacted only with a single serum sample from an E. multilocularis patient. It was concluded that a combination of ELISA and IEP was useful for the diagnosis of hydatid disease, that ELISA at a single dilution could be useful as a screening test where other larval cestode infections were not prevalent and that ELISA was not of value for post-operative surveillance.

Antibodies↗

Clinical field efficacy and safety of pyrantel pamoate paste (19.13% w/w pyrantel base) against Anoplocephala spp. in naturally infected horses.

Clinical field trials were conducted at five geographical locations in the USA (Oklahoma, Wisconsin, Tennessee, Virginia and Idaho) to evaluate the efficacy and safety of pyrantel pamoate paste (19.13%, w/w, pyrantel base) administered at the recommended dosage of 13.2 mg pyrantel base/kg (6.0 mg pyrantel base/lb) body weight (b.w.) against tapeworm infections of Anoplocephala spp. in naturally infected horses. Horses at each study site were allocated by restricted randomization based on the cestode status (positive or negative) of pre-treatment fecal egg counts to complete sets of four animals each or incomplete sets of fewer than four animals. Within sets comprising of two to four horses, one animal was randomly allocated to receive placebo vehicle paste and the remaining horse(s) received pyrantel pamoate paste administered orally at a minimum dosage of 13.2 mg pyrantel base/kg b.w. on Test Day (TD) 0. Single animal sets received pyrantel pamoate paste. Fecal samples of horses were collected and examined for equine tapeworm (Anoplocephala spp.) eggs a minimum of four times (once or thrice between TD -28 and -14, twice between TD -14 and -7, and once on TD 0) prior to treatment on TD 0. Fecal samples of horses that were positive for cestode infection pre-treatment were examined for cestode eggs on TD 7, 8, 9, 14, 15 and 16. Cestode-negative pre-treatment horses were not sampled again after treatment. A total of 241 horses (141 mares, 16 stallions and 84 geldings; 6 months-30 yrs of age; 173-646 kg; 13 recognized breeds and various crossbreds) were evaluated. The prevalence of Anoplocephala spp. determined by pre-treatment fecal examination ranged from 38.3% in Idaho to 68.1% in Tennessee with an overall prevalence of 52.3%. Ninety cestode-positive and 88 cestode-negative horses were treated with pyrantel pamoate paste, 36 cestode-positive and 27 cestode-negative horses were treated with placebo vehicle paste. Overall, 178 horses were treated with pyrantel pamoate paste, and 63 horses were treated with placebo paste. Of the 178 horses treated with pyrantel pamoate paste, no drug related, adverse clinical or neurological health events were observed. No doses of pyrantel pamoate paste were refused or lost during dosing. At each post-treatment time sampling interval, significantly fewer cestode eggs (P < 0.0115) were passed by cestode-positive horses treated with pyrantel pamoate paste compared to cestode-positive horses that received placebo paste. Efficacy of the pyrantel pamoate paste treatment ranged from 92 to 96% from TD 7 to TD 16 with an overall efficacy of 95%. The results of these trials demonstrated that pyrantel pamoate paste (19.13%, w/w, pyrantel base) administered orally at a dosage of 13.2 mg pyrantel base/kg b.w. is highly efficacious (95%) against Anoplocephala spp. and safe for use in horses with no adverse clinical or neurological health events observed under field use conditions.

Administration, Oral↗

The cellular response of the fowl small intestine to primary and secondary infections of the cestode Raillietina cesticillus (Molin).

Infections of Raillietina cesticillus in the small intestine of the fowl caused a mononuclear leucocyte infiltration, which occurred in the tissues around the worm scolices and was especially prevalent in challenge infections. There was no evidence of vascular congestion or of a neutrophilic response, and the cellular reaction seemed to consist of a local proliferation of lymphoid tissue. Mast cell and pyroninophylic cell numbers increased in the intestinal mucosa of birds with longstanding primary infections and with secondary infections, but very little eosinlophil infiltration was detected and the globule leucocyte response was minimal. The infections had no effect on the numbers of theliolymphocytes and goblet cells. Challenge infections did not result in an increased level of serum antibodies, but more cells containing globulin seemed to be present in the intestinal mucosa of these birds. The interrelationships of the various cell responses to the cestode and the origin of the globule leucocyte are discussed in the light of previous work on helminth infections.

Animals↗

Molecular cloning of Taenia taeniaeformis oncosphere antigen genes.

Infection of mice with the cestode Taenia taeniaeformis exhibits several important features common to other cestode infections, including the ability to vaccinate with crude antigen mixtures. Partial purification of the protective oncosphere antigens has been reported with a cutout from deoxycholate (DOC) acrylamide gels; this cutout was called fraction II (FII), and comprises approximately 10% of total DOC-soluble oncosphere antigen. Western blots of DOC gels probed with anti-FII antisera revealed a series of 3-5 discrete bands within the FII region. Further fractionation of the FII antigens on DOC gels was impractical due to limitations in supply of oncospheres, so a cDNA library was constructed from 150 ng of oncosphere mRNA and screened with alpha-FII antisera. Two distinct clone families were identified, oncA and oncB. Antibodies affinity-purified on either of two representative members, oncA1 and oncB1, recognised all the FII bands. Individual FII bands excised from a DOC gel resolved into an overlapping series of molecules when re-run on SDS-PAGE, indicating that each FII band consisted of several polypeptides of differing molecular weight. Immunoprecipitates resolved on SDS-PAGE revealed that alpha-FII recognised 3 major oncosphere antigens, of 62, 34 and 25 kDa; antisera against oncB precipitated both the 34- and 25-kDa antigens, whereas alpha-oncA antisera precipitated the 62-kDa antigen. We conclude that oncA and oncB encode the major antigens in the FII complex. The 62-kDa antigen encoded by oncA1 was the only common antigen precipitated by anti-FII and two other antisera raised against different protective extracts, suggesting that it may be a protective component in all three. Southern blot results indicate that oncA and oncB are distinct genes present at low copy number in the genome. Evidence is also presented suggesting that some cestode mRNAs, including oncA, may use variant polyadenylation signals.

Amino Acid Sequence↗

Anthelmintics. Current concepts in the treatment of helminthic infections.

This article discusses the anthelmintics now in common use and describes their mode of action and toxic side effects. The drugs reviewed include: pyrantel pamoate, mebendazole, piperazine, thiabendazole, niclosamide, praziquantel, niridazole, oxamniquine and diethylcarbamazine. Most of the common roundworm intestinal infections respond to treatment with pyrantel pamoate, which has the advantage of single-dose therapy. Trichuriasis requires therapy with mebendazole, while the filariases are treated with diethylcarbamazine. There is no specific therapy for trichinellosis, but its symptoms can be alleviated. Intestinal cestode infections respond to treatment with niclosamide and cerebral cysticercosis to praziquantel, but echinococcal hydatid disease still requires surgical intervention in certain cases, although prolonged treatment with mebendazole shows promise. The greatest recent advance in the therapy of helminthiases is the development of praziquantel which effectively treats the most severe of these infections.

Anthelmintics↗