Diagnosis of toxoplasmosis in immunosuppressed mice using the polymerase chain reaction (PCR) and the enzyme linked immuno-sorbent assay (ELISA) techniques.

In the present study, Toxoplasma infection with the virulent and avirulent strains in both immunocompetent and immunosuppressed mice was diagnosed using the MDS ELISA for detection of CA in sera and the PCR for demonstration of DNA in livers, brains and mononuclear cells of blood. Both techniques proved to be convenient, especially in immunosuppressed mice.

The possibility of transplacental transmission of experimental schistosomiasis.

Congenital transmission of Schistosoma mansoni and S. haematobium in mice was studied by experimentally infecting pregnant mice on day three, or nine or 14 of gestation. None of the pups born to mothers infected in early or mid-pregnancy were infected. However, several pregnancies ended in abortion ranging between 10%-40%. On the other hand, eight out of 35 pups born to mice infected with S. mansoni and five out of 30 pups born to mice infected with S. haematobium in late pregnancy were found to harbour schistosomes with granulomas recovered in their livers and intestines. These findings show that congenital infection of mice with S. mansoni and S. haematobium could occur when pregnant mice were infected during late pregnancy. This may have important implications not only for mice, but also for other mammalian hosts of schistosomes, including man.

Role of anti-Trichinella spiralis antibodies and interferon-gamma in the protection against the enteral phase of experimental trichinosis.

Expulsion of adult Trichinella spiralis is the result of a complex immunologically mediated response. Experiments in mice demonstrated that IFN-gamma, released by mesenteric lymph nodes (MLN) during infection play a major role. However, the role of mucosal and serum antibody responses is thought to be limited. Working on the intestinal phase, this study investigated, the role played by antibodies, transferred from vaccinated infected animals, in the immune response in comparison to that obtained by IFN-gamma administration. Transfer of antibodies gave 82.7% protection, while IFN-gamma in a dose of 1 x 10(4) U gave 98.4% protection. The use of half the previous dose induced a protection of 58.3%. These data indicate that vaccination followed by infection could generate antibodies capable of producing a protective immune response against the intestinal phase of T. spiralis. This reached a level near to that obtained by IFN-gamma administration.

Detection of Microsporidia by different staining techniques.

Previous detection of Microsporidia relied mainly on electron microscopy and histopathology. Recently, non invasive methods were able to recognize this microorganism. In the present study, different stains were used as a means of diagnosing spores of Microsporidia in stool samples of immunosuppressed patients. The original modified trichrome stain (MTS) was used as a standard screening technique for all stool samples. Positive samples for Microsporidia were then stained with the trichrome blue stain, Didier's trichrome blue stain, acid-fast trichrome stain (AFT), modified Ziehl-Neelsen stain, giemsa stain and calcofluor white M2R stain. Both calcofluor and the AFT stains were most efficient. They could simultaneously detect coccidial oocysts and microsporidial spores. This is beneficial and time-saving in the diagnosis of stool samples of immunosuppressed patients, which usually contain more than one opportunistic protozoon. Both stains are easy to perform and require the least amount of staining and examination.

The effect of flubendazole on the course of Trichinella spiralis infection in mice: parasitological study.

This work planned to study the effect of flubendazole against different stages of Trichinella spiralis infection in mice. Three groups of experimental animals were examined: control group, group I treated three days post infection and group II treated four week post infection. In group I, flubendazole was shown to be a very potent agent in killing Trichinella spiralis adults and larvae, when given orally in a dose of 20 mg/kg for five consecutive days. This is evidenced by the significant reduction in number, length of the female and reproductive capacity as well as the absence of the muscle larvae. However, in group II, the effect of the drug although still significant yet diminished in all parameters as compared to the early treatment. These results evoke ideas for further design of other treatment and control of the disease.

A study on patients with eosinophilia of suspected parasitic origin.

A study of 53 patients with eosinophilia of suspected parasitic origin was conducted. Investigations done for each case included, stool and urine examinations, absolute eosinophilic count and countercurrent immunoelectrophoresis (CIEP) using crude antigens of Fasciola hepatica, Schistosoma mansoni worms, Trichinella spiralis and Toxocara canis larvae, and hydatid fluid. Stool examination revealed six cases with Fasciola eggs, two with Ascaris lumbricoides and one with S. mansoni eggs. The eosinophilic count ranged from 682 to 10560 cell/mm3. 26 cases showed mild eosinophilia, 24 moderate and three marked eosinophilia. Out of the 53 cases examined by the CIEPT, 30 were positive with Fasciola antigen. Their eosinophilic count ranged from 770 to 10560 cell/mm3. Six cases were positive with hydatid antigen and had an eosinophilic count ranging from 825 to 2970 cell/mm3. Only one case was positive with S. mansoni antigen and its eosinophilic count was 935 cell/mm3. 16 cases were negative with the different antigens used and their eosinophilic count ranged from 682 to 2200 cell/mm3.

Schistosoma mansoni: a comparative study on two cercarial transformation methods.

An agar: gelatin plate method, incorporating varying concentrations of linoleate was devised to measure cercarial penetration and transformation in vitro. Schistosoma mansoni cercariae were stimulated over a wide range of linoleate concentrations, while the transformation process occurred over a narrow range. Penetration rates rose gradually until at linoleate concentrations of 0.3 mM and greater, where penetration approached 100% while transformation just started to occur. The latter then reached maximum (90%) at 3 mM. This optimal concentration of linoleate leading to maximal transformation was then compared with a mechanical transformation method in relation to proteolytic activity and nuclear content. It was found that, proteolytic activity was higher by the chemical than by the mechanical transformation method. The nuclear content decreased by both techniques. This decrease was greater when the mechanical transformation method was applied.

Evaluation of enzyme-linked immunosorbent assay and counter-current immunoelectrophoresis in diagnosis of experimental trichinosis.

Definite diagnosis of trichinosisis mainly by direct demonstration of larvae, however, these methods are neither feasible nor sensitive. Thus, confirmation relies mainly on positive serology. In this study, enzyme-linked immunosorbent assay (ELISA) and counter-current immunoelectrophoresis (CIEP) using crude larval antigen were assessed as a tool in the diagnosis of trichinosis. Sera were tested one, two, five, eight, and twelve weeks post-infection. It was found that ELISA was positive in all tested sera from the second till the 12th week (100% sensitivity). As regards CIEF, 36% of the sera were positive two weeks post-infection, while all sera were positive at 5 and 8 weeks. Ninety per cent of the tested sera gave positive results at the 12th week post-infection. ELISA proved to be more sensitive in diagnosing trichinosis both early and late in infection, while CIEP test was more specific since no false positive results were noticed.