Domestic cats, 11 other species of carnivorous mammals, 6 species of snakes, and white-backed vultures were tested for their possible role as definitive hosts of Benoitia besnoiti by feeding with cystic material from chronically infected bovines. None of the species tested is a definitive host; hence, the life cycle of this parasite remains obscure. In attempts to produce clinical cases of besnoitiosis by experimental infection, bovines were inoculated IV, SC, and IP with cystozoites or tachyzoites. Immunosuppression of the animals was essential for the development of severe cases and skin lesions; cystozoites proved to be more pathogenic than tachyzoites.
Sporocysts collected from the feces of a Palestinian viper (Vipera palaestinae) were administered orally to species of various rodent genera such as Mus, Microtus, Mastomys, Meriones and Oryctolagus. Infections developed only in laboratory mice (Mus musculus). This investigation established the life cycle of Sarcocystis muriviperae in the laboratory. S. muriviperae is described as a new species, based on light and electron microscopic observations and repeated transmission studies. Naturally and experimentally infected Palestinian vipers both excreted structurally identical sporocysts measuring 9.6 micron (8.8-10.5 microns) by 12.2 microns (11.7-12.9 microns). Sporulation inside the snakes' intestine is completed between 14 and 19 days post-inoculation (p.i.). Rosette-like schizogonic stages were found in the liver cells of laboratory mice 9-10 days after infection with sporulated sporocysts. Sarcocysts measured up to 1,000 microns in length on day 36 p.i. and were mainly filled with metrocytes. The septated sarcocysts found 136 or 165 days p.i. reached a length of 5-8 mm and a width of 150-400 microns. The primary sarcocyst wall formed cauliflower-like branched protrusions about 3.5 microns in length.
The sequential appearance of variable antigen types (VATs) of a clone of Trypanosoma evansi was studied in four ponies. Using luminol-dependent chemiluminescence, VAT populations which had been isolated from parasitemic peaks of single ponies, were tested for specificity with serum samples collected from other ponies. When antibody activity was demonstrated in a combination of trypanosomes and serum, it was concluded that a major VAT appeared in common. In the serum of all animals antibody activity was demonstrated to all VAT populations isolated from the other ponies during the first 4 weeks of infection, indicating that up to this moment in all four animals the same major VATs developed. The sequence of major VATs was very similar in all ponies. Several parasitemic waves consisted of more than one major VAT, and in another pony a certain major VAT developed either in the same or in a neighbouring wave of the parasitemia.
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