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Suppression of Peripheral Eosinophilia by the Coccidium Eimeria nieschulzi (Apicomplexa: Eimeriidae) in Experimentally Infected Rats
Steve J. Upton, Lillian F. Mayberry, John R. Bristol, Sam H. Favela and Gilbert R. Sambrano
The Journal of Parasitology
Vol. 73, No. 2 (Apr., 1987), pp. 300-308
Stable URL: http://www.jstor.org/stable/3282082
Page Count: 9
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Four groups of 60 rats each were used to examine interspecific interactions between Eimeria nieschulzi and Nippostrongylus brasiliensis. Rats in group 1 served as uninoculated controls. Group 2 rats were each injected subcutaneously with 2.0 × 103 larvae of N. brasiliensis. Group 3 rats were each inoculated per os with 2.5 × 105 sporulated oocysts of E. nieschulzi. Rats in group 4 were first infected with 2.0 × 103 larvae of N. brasiliensis and, at 8 days postinoculation, with 2.5 × 105 oocysts of E. nieschulzi. Ten animals from groups 1-3 were sacrificed at 4-day intervals postinoculation and group 4 rats were sacrificed at 4-day intervals beginning after the secondary infection. Blood smears were prepared from each animal to determine differential blood cell counts, bone marrow was examined at the times of peak infection for absolute and relative numbers of eosinophils, portions of the duodenum and jejunum were examined histologically for mast cells, and feces obtained from the cecum and large intestine were examined for ova/gram of feces. Results revealed that relative numbers of peripheral neutrophils and monocytes became elevated during the course of infection for all infected animals, and rats infected with the helminth only also had elevated eosinophil levels. However, rats infected singly with E. nieschulzi, or concurrently with the coccidium and helminth, had peripheral eosinophil levels that were not significantly different from controls. Both absolute and relative numbers of bone marrow eosinophils rose during the course of infection with single and concurrent N. brasiliensis infections, however, the presence of the coccidium appeared to prevent release of the eosinophils from the bone marrow. Numbers of mucosal mast cells rose during the course of infection with both coccidian annd helminth, however, E. nieschulzi partially inhibited mast cell numbers during concurrent infections, below those that would normally be present during single N. brasiliensis infections. Patency of N. brasiliensis infections was significantly lengthened (P < 0.001) in animals infected concurrently over those infected only with the helminth.
The Journal of Parasitology © 1987 The American Society of Parasitologists