Praziquantel in the treatment of Schistosoma mansoni infection: comparison of 40 and 60 mg/kg bodyweight regimens.

Two different regimens of praziquantel, 40 mg/kg in a single dose and 60 mg/kg in two divided doses administered 6 hr apart, for the treatment of Schistosoma mansoni infection were compared in Abu Homos, Egypt. Participants in this study included 1,588 subjects of both sexes between five and 50 years old from two rural communities; 730 from Farshout and 858 from Om El-Laban. The prevalence of S. mansoni infection was 57.9% in Farshout and 69.0% in Om El-Laban. Infected subjects received 60 mg/kg of praziquantel in two divided doses 6 hr apart at Farshout and 40 mg/kg in a single dose at Om El-Laban. Eight to ten weeks after treatment, three stool samples were collected from each treated subject on three consecutive days and evaluated quantitatively by the modified Kato technique. The failure rate was significantly higher at Om El-Laban than at Farshout (14.5% versus 4.1% (odds ratio [OR] = 3.95, P < 0.0001). A significantly higher failure rate was consistent after adjustment for age and number of excreted S. mansoni eggs per gram of feces before treatment (OR = 3.75, P < 0.0001). In spite of differences among cure rates between the two regimens, we recommend 60 mg/kg on an individual basis but not for population treatment, since administration of a single dose of a drug is more practical than two doses given 6 hr apart.

Topical niclosamide as a protective agent against schistosome infection.

Niclosamide, as a semisolid pharmaceutical form suitable for external use, was used in 4 different concentrations (0.5%, 1%, 2% & 4%) to paint albino mice tails at different periods before exposure to infection with S. mansoni cercariae. Complete protection (100%) was achieved in all mice painted on the same day, the previous day and 3 days before exposure to cercariae irrespective to the niclosamide concentrations. Neither eggs nor worms were detected. Also, no pathological changes were found in livers, spleens or intestines of those mice. On the other hand, no protection against infection was achieved in mice painted with, 0.5% or 1%, 7 days before exposure to cercariae. Partial protection (25% and 40%) was gained in mice painted with 2% or 4% concentration of the drug respectively. It can be concluded that locally application of niclosamide as an ointment can completely prevent the infection with S. mansoni for three days. So, testing the promising drug for human trials to evaluate its efficacy specially for those at high risk is recommended.

Testicular changes in rats after Trichinella spiralis infection.

Infection of rats with Trichinella spiralis was found to be associated with testicular enlargement. A paucity of Leydig cells with marked oedema of interstitial areas were observed. Most of the seminiferous tubules were lined by spermatogonia and primary spermatocytes. T. spiralis larvae were not detected in the testes. Using the indirect immunoperoxidase procedure, T. spiralis antigen was detected as weak brown staining. The antigen was diffusely distributed in the cytoplasm of spermatogenic cells, Sertoli cells and focally around the tubular basement membrane of the infected rats. The significance of the results was discussed.

Effect of Hymenolepis nana on the mouse ileal mucosal cells: histochemical studies.

Histochemical studies of the ileal mucosal cells of mice experimentally infected with H. nana revealed definite increase in mucous secretions indicating increased activity of the goblet cells in response to mucosal irritation. The activity of acid phosphatase was also increased representing a sort of defence mechanism against the attached worms. The activities of ATP-ase and NADH diaphorase enzymes were decreased indicating disturbance in the metabolic and transport processes and in the absorptive function of the intestinal epithelial cells.

Cell-mediated immune response in experimental infection with H. heterophyes.

Experimental infection of puppies with Heterophyes heterophyes was associated with marked cell-mediated immune response that manifested itself by increase of T-cell count and leucocyte migration. The degree of cell-mediated immune response was inversely proportional to the intensity of infection. The significance of the results was discussed.

Cross-reactions in immunodiagnosis of patients infected with Schistosoma, Fasciola and Heterophyes using ELISA.

Cross-reactions in immunodiagnosis using schistosomal soluble egg antigen (SEA) and Fasciola adult worm antigen in cases with fascioliasis, heterophyiasis and schistosomiasis were studied by ELISA techniques. False positive reactions occurred in 10% of cases with fascioliasis and heterophyiasis respectively when using schistosomal SEA. Using Fasciola crude antigen, false positive reaction occurred in 25% of cases with schistosomiasis and 35% with heterophyiasis. The specificity of SEA in heterologous cases was 87% while that of Fasciola antigen was 70%. This difference was found to be statistically significant.

Comparative study between latex agglutination and indirect immunofluorescent antibody tests in diagnosis of toxoplasmosis.

The latex agglutination test (Toxolatex) was compared with the indirect immunofluorescent antibody test (IFAT) in investigating one hundred and fifty human sera. Both techniques showed 90.7% agreement. The mean titre of each test was significantly higher in cases with fever or lymphadenopathy than cases without these manifestations. It was concluded that the latex test provides a rapid and simple test in toxoplasmosis that can be used to exclude negative cases as nearly no false negative results were obtained. However, positive cases by latex agglutination should be confirmed and quantitated by another standardized technique.

Effect of some anthelmintics on Hymenolepis nana in albino mice.

Mebendazole and emetine (orally and parenterally) were used to treat mice infected with H. nana. Yomesan, in a single oral dose, was also used as a standardized well-known cesticidal drug. Emetine had a marked effect on cysticercoids leading to highly significant reduction in their number. Also, it caused complete removal of adult worms in infected mice. Mebendazole had no effect on the cysticercoid stage, but it caused significant reduction in the number of adult worms. Yomesan, showed a marked lethal effect on both the cysticercoids and adult worms leading to highly significant reduction in their number.

Toxoplasmosis among cases of chronic tonsillitis.

One hundred cases aged 4-20 years and suffering from chronic tonsillitis were examined for Toxoplasma antibodies using indirect immunofluorescent test (IFAT). It was found that 37% of them were positive for toxoplasmosis. 41.5% of hypertrophic cases and 32% of atrophic ones had toxoplasmosis but the difference was statistically insignificant. The mean antibody titres were higher in both atrophic and hypertrophic cases than in the control group. The patients aged from 11-20 years had a higher titre of Toxoplasma antibodies than those aged below ten years. Trials to detect tachyzoites, cysts or pseudocysts in fixed paraffin sections using Hx & E, PAS or Giemsa stains were not successful. The histopathological picture of tonsils removed from positive cases of toxoplasmosis showed characteristics of toxoplasmic lymphadenitis.