Detection of coproantigen in early trichinellosis.

Trichinellosis has become undoubtedly worldwide in distribution. Its diagnosis relies largely on the serodiagnostic procedures which are of great value but unfortunately miss the enteric phase. This could be a serious diagnostic problem in the absence of corresponding epidemiological data and typical symptoms and signs of the disease. In this study the possibility of coproantigen detection, as an early diagnostic aid in trichinellosis, was investigated in mice experimentally infected with Trichinella spiralis. A modified double sandwich ELISA was developed using polyclonal antibodies raised in rabbits and guinea pigs against larval somatic antigens. The first detection of coproantigen was as early as the first day post infection, gradually increasing to reach its peak on the seventh day and then decreasing to disappear completely on the third week post infection. Another test, the coagglutination test (Co-A) was used, and this test confirmed the previous results. The finding of this study suggest that the coproantigen detection could be exploited to confirm ongoing early Trichinella spiralis infection. This fast and easy to use diagnostic method should improve the early infection in human.

Experimental conversion of virulent RH Toxoplasma gondii tachyzoites in vitro.

We aimed to induce conversion of RH-stain tachyzoites to bradyzoites by changing the pH of the culture medium. Alkalization of the medium to pH 8 induced morphological changes in the cultured tachyzoites. The majority of the organism increased in size and changed from a regular crescent shape to a rounded or ovoid shape. Cyst-like structures were formed. Using a computerized image analyser, significant differences in the size of the whole organisms and in their nuclei were observed compared to the control group. The converted organisms also showed significant differences from the control group by quantitative DNA analysis, and did not infect mice.

Experimental conversion of virulent RH Toxoplasma gondii tachyzoites in vitro

We aimed to induce conversion of RH-stain tachyzoites to bradyzoites by changing the pH of the culture medium. Alkalization of the medium to pH 8 induced morphological changes in the cultured tachyzoites. The majority of the organism increased in size and changed from a regular crescent shape to a rounded or ovoid shape. Cyst-like structures were formed. Using a computerized image analyser, significant differences in the size of the whole organisms and in their nuclei were observed compared to the control group. The converted organisms also showed significant differences from the control group by quantitative DNA analysis, and did not infect mice

Detection of Cryptosporidium parvum antigen by co-agglutination test and ELISA.

Confirmation of the presence of Cryptosporidium in environmental samples is laborious, costly and often difficult. We report here a simple and economic slide agglutination test (co-agglutination test) for detecting cryptosporidial antigen in stool, serum and water. The results show that as a screening method co-agglutination is clearly superior to enzyme-linked immunosorbent assay (ELISA) and modified Ziehl-Neelsen staining, although ELISA is more accurate. The co-agglutination test is recommended for application as a new tool for detecting cryptosporidial antigen in large-scale epidemiological surveys.

Coccidial infection in immunosuppressed mice: prophylaxis and treatment with dehydroepiandrosterone.

Cryptosporidiosis and toxoplasmosis are diseases caused by opportunistic coccidial parasites that can lead to life-threatening infection in immunocompromised patients. We evaluated dehydroepiandrosterone as prophylaxis and therapy in immunosuppressed mice infected with Cryptosporidium parvum and avirulent Toxoplasma gondii. Mice were infected with either Cryptosporidium oocysts or Toxoplasma cysts. Assessment was by mortality rates, parasitic counts and electron microscopic studies. Mortality rates were significantly reduced in all treated groups. A significant reduction in the cryptosporidial oocyst count in stool and intestinal villi and in Toxoplasma cysts in the brains of infected mice was observed in all the groups. The effect of the drug was greater when given prior to infection.

Coccidial infection in immunosuppressed mice: prophylaxis and treatment with dehydroepiandrosterone

Cryptosporidiosis and toxoplasmosis are diseases caused by opportunistic coccidial parasites that can lead to life-threatening infection in immunocompromised patients. We evaluated dehydroepiandrosterone as prophylaxis and therapy in immunosuppressed mice infected with Cryptosporidium parvum and avirulent Toxoplasma gondii. Mice were infected with either Cryptosporidium oocysts or Toxoplasma cysts. Assessment was by mortality rates, parasitic counts and electron microscopic studies. Mortality rates were significantly reduced in all treated groups. A significant reduction in the cryptosporidial oocyst count in stool and intestinal villi and in Toxoplasma cysts in the brains of infected mice was observed in all the groups. The effect of the drug was greater when given prior to infection

Detection of Cryptosporidium parvum antigen by co-agglutination test and ELISA

Confirmation of the presence of Cryptosporidium in environmental samples is laborious, costly and often difficult. We report here a simple and economic slide agglutination test [co-agglutination test] for detecting cryptosporidial antigen in stool, serum and water. The results show that as a screening method co-agglutination is clearly superior to enzyme-linked immunosorbent assay [ELISA] and modified Ziehl-Neelsen staining, although ELISA is more accurate. The co-agglutination test is recommended for application as a new tool for detecting cryptosporidial antigen in large-scale epidemiological surveys

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.