Necrotic enteritis in chickens: development of a straightforward disease model system.

The interaction between Eimeria species and Clostridium perfringens was investigated in two different necrotic enteritis (NE) models: 120-day-old broilers were used in two separate experiments consisting of six groups (n=10) each. Besides controls, chickens were infected with coccidia on study day (SD) 18 (Eimeria maxima and Eimeria acervulina (experiment 1) or Eimeria tenella and Eimeria brunetti (experiment 2) and/or a NetB toxin positive C perfringens strain (both experiments: SD 14 or SD 22, respectively)). Body weight, feed intake, mortality rate, clinical disease, Eimeria species oocyst excretion and C perfringens counts were recorded. NE and coccidiosis specific lesion scores were assessed (SD 24 and SD 30). In coinfected groups, NE-typical clinical signs occurred. Coccidiosis-specific lesions were most severe in coinfected groups (significant for E tenella, P<0.05). Most pronounced NE lesions occurred in coinfected chickens compared with C perfringens monoinfected groups (experiment 2, C perfringens infections on SD 22: P<0.05). In experiment 2, E tenella antibody levels were (non-significantly) higher in coinfected groups than in Eimeria species monoinfected groups. Thus, infection with E tenella and Eimeria brunetti followed by C perfringens inoculation is regarded as an easy to handle and suitable model for investigations into NE of chickens.