Sarcocystis Hominis Research Articles

Evaluation of two Neospora caninum recombinant antigens for use in an enzyme-linked immunosorbent assay for the diagnosis of bovine neosporosis.

Neospora caninum is a recently described apicomplexan parasite which causes paralysis and death in dogs. Neospora parasites also cause abortion and neonatal morbidity in cattle, sheep, goats, and horses, and neosporosis is emerging as an important cause of bovine abortion worldwide. The purpose of this study was to identify N. caninum cDNA clones encoding antigens that would be useful for the immunodiagnosis of bovine neosporosis. Two N. caninum tachyzoite cDNA clones expressing antigens that were recognized by serum from naturally and experimentally infected cattle were identified. The DNA sequences of these clones were determined, and the inserts were subcloned into the plasmid expression vector pTrcHisB. Both recombinant antigens, expressed as fusion proteins with a His6 tag, were purified on a nickel-chelating affinity column and evaluated in separate enzyme-linked immunosorbent assays (ELISAs). Both recombinant antigen ELISAs were capable of distinguishing between sera from Neospora-infected cows and sera from uninfected control cows. Furthermore, both assays were able to detect an antibody response in animals that were experimentally inoculated with N. caninum. Neither antigen showed evidence of cross-reactivity with serum from animals inoculated with the closely related parasites Toxoplasma gondii, Sarcocystis cruzi, Sarcocystis hominis, and Sarcocystis hirsuta.

Amoebiasis and Giardiasis

Intestinal protozoan infections involving humans are by no means confined to tropical/subtropical countries; however, it is here that maximal prevalence, and consequently, morbidity, assumes a major practical importance. Coccidial infections (Cryptosporidium spp., Isospora belli, Sarcocystis hominis and Cyclospora spp.), and Blastocystis hominis and Microsporidium spp., which were previously underrecognised, have come to the fore in the present era, largely in association with HIV infection. Nevertheless, these organisms can induce self-limiting infection in travellers and other individuals in countries in which standards of sanitation/public health are less than satisfactory. Overall, however, there can be no doubt that Giardia lamblia (also known as G. intestinalis and G. duodenalis) and Entamoeba histolytica are numerically the most important protozoan parasites to involve the gastrointestinal tract. Whereas trophozoites of the former organism are virtually confined to the small intestinal lumen, the extra-intestinal manifestations of E. histolytica infection are of greater importance than its colorectal pathogenic properties. This review concentrates on the prevalence of the 2 infections in different populations; this reflects both incidence and outcome, including duration of illness. Epidemiology is also addressed. Routes of transmission of the 2 infections are covered, together with morbidity and, in the case of E. histolytica infection, mortality also.

Experimental Sarcocystis hominis Infection in Cattle: Lesions and Ultrastructure of Sarcocysts

Five calves inoculated orally with 10(5)-10(6) sporocysts of Sarcocystis hominis from human feces were necropsied 10, 18, 24, 111, and 222 days postinoculation (DPI). Calves became febrile (greater than 40-41 C) between 10 and 24 DPI and developed mild anemia (packed cell volumes were reduced by 40% of initial values) between 29 and 57 DPI but otherwise remained clinically normal. Focal hepatitis, mesenteric lymphadenitis, and myocarditis were seen in calves at 10, 18, and 24 DPI. No stages of the parasite were found at any of these times except for a few merozoites in macrophages associated with myocardial lesions in the calf necropsied 24 DPI. Mature sarcocysts at 111 and 222 DPI were up to 950 microm long and their walls were up to 6 microm thick. They were found only in skeletal muscles. One immature sarcocyst was seen in the myocardium of the calf at 222 DPI.