ABSTRACT
In pigs, two genera of intestinal coccidia are recognized, Eimeria and Cystoisospora. Eimeria species of pigs parasitize the small intestine. Cystoisospora suis is the most important parasitic enteropathogen of suckling piglets. In susceptible pigs, it causes nonhemorrhagic diarrhea of pasty to watery consistency and whitish-gray to yellow color, which is unresponsive to most antibiotic treatments. The clinical outcome of cystoisosporosis in pigs is strongly age-dependent. The small intestines of affected piglets are edematous and filled with yellow, smelly fluid. Infection with C. suis seems to inhibit the establishment of Salmonella typhimurium in the intestines as well as in mesenteric lymph nodes in pigs when parasite infection takes place shortly after bacterial inoculation. Prevention and control are therefore of paramount importance to minimize the impact of coccidiosis in the pig farming industry. Toltrazuril-resistant C. suis are a potential threat to pig farming, as no other effective and economically sustainable alternative treatment is available.
