Schistosoma mansoni: the immune response against cercarial glycocalyx.

Schistosoma mansoni cercarial glycocalyx was separated and purified by Sephacryl-300 SR. It was found to stimulate the humoral immune response in mice injected with it. Antiglycoalyx antibodies raised in CD/1 mice were found to be cytotoxic to schistosomula in vitro. But conversely, no protective effect was demonstrated in vivo. Eosinophil-mediated cytotoxicity was found to have no effector function in the murine immune response against schistosomes. A monoclonal antiglycocalyx IgM was prepared during our study. It was found to have no cytotoxic effect on schistosomules in vitro. However, it was found to have an inhibitory activity blocking the cytotoxic effect of other antiglycocalyx isotypes in the immune mouse. The contradiction between the result of antiglycocalyx antibody-mediated cytotoxicity obtained in vivo and that obtained in vitro is in itself revealing and suggests that the effect is crucially dependent upon factors as yet poorly understood.

Observations on possible immunity to reinfection among school children after schistosomiasis treatment.

A total of 72 bilharzial mansonian school children aged 6-12 years were studied before and six months after praziquantel (PZQ) treatment. After treatment, 21 cases showed reinfection while 51 were resistant. Using ELISA specific antibody assays titre levels of IgM, IgG, IgA & IgE for soluble egg antigen (SEA) and soluble worm antigen (SWAP), were higher among resistant cases than among reinfected ones before and after treatment. The levels of specific IgA & IgE among resistant cases were significantly higher than among reinfected cases after treatment. This may indicate the integrity of immune system and prominant humoral immune response.

Detection of Giardia antigen in stool samples before and after treatment.

A double antibody sandwich ELISA technique, using a chromatography purified Giardia antiserum, was applied to detect faecal antigen in patients infected with Giardia lamblia before and after treatment. The assay could detect antigens in 98% of infected cases with false positive reactions in 3 cases infected with E. histolytica. There was a significant direct relation between the antigen level in stool samples and the number of Giardia cysts. The mean level of copro-antigen was slightly lower in children, below 10 years, than in older patients, without significant difference. On the other hand, the lowest cyst count was noticed in elder patients, over 20 years. The level of faecal antigens decreased significantly after successful treatment in patients with giardiasis. It was concluded that detection of Giardia antigens by ELISA technique in the stool samples was a highly sensitive (98%) and specific (91%) diagnostic method. It is also considered as a good monitor for treatment success.

Study of free living amoebae in Egypt.

At different locality in Egypt, free living amoebae (FLA) were detected in 32%, 20% and 4% of water samples obtained from swimming pools, surface water canals and tap water respectively. Naegleria spp. were identified from 12 (75%) out of 16 swimming pool samples and 6 (60%) out of 10 surface water & canals samples from different Governorates in Egypt, while Acanthamoeba spp. were identified from 4 (25%) of 16 swimming pools samples, 4 (40%) out of 10 surface water & canals samples and 2 (100%) tap samples. The isolated FLA in the present study were non-pathogenic as proved by the pathogenicity test.

The prevalence of Entamoeba gingivalis and Trichomonas tenax in periodontal disease.

Two hundred patients (100 males and 100 females) having either marginal periodontitis or gingivitis were examined for detection of E. gingivalis and T. tenax. E. gingivalis was more prevalent among patients with periodontitis particularly females, while T. tenax was not discovered entirely in both patients and control groups.