Paratyphoid infection induced by Eimeria tenella in the broiler-type chickens

Two experiments were conducted to examine the effects of the Eimeria tenella infection on mortality, weight gain and lesions of paratyphoid infection in broilers. When 4-day-old birds were exposed to approximately 106 colony forming units (CFU) of S. typhimurium for 5 consecutive days after the coccidial inoculation, the effect on mortality of concurrent infection, 17.7%, was about the sum of the E. tenella-inoculated group and the S. typhimurium-inoculated group (15.5%). When 11-day-old birds were similarly exposed to approximately 107 CFU of S. typhimurium, the gross lesions of paratyphoid infection characterised by visible foci over the entire liver were observed only in the concurrently infected birds killed 10 and 14 days after coccidial inoculation. The S. typhimurium counts in the liver and spleen of birds killed 7 days after coccidial inoculation were significantly greater than that of birds inoculated with S. typhimurium alone. In both experiments, the S. typhimurium counts in the caecal contents of birds inoculated with both organisms were significantly greater than those of birds infected with S. typhimurium alone.