[Epidemiology of Eimeria in broiler chicks as influenced by anticoccidial agents]

1,729 Flocks from seventy-three broiler farms, belonging to three integrated groups, were studied for the presence of coccidiosis during a five-year period. An overall average of 50.3 per cent of the flocks was found to be infected. There were marked difference between the integrated groups. Differences were also observed in the severity of infections, expressed in a relative coccidiosis score. A relatively high incidence of coccidiosis was particularly observed in autumn and winter flocks. Other conditions such as respiratory tract infections and leg defects were found to present a different seasonal pattern. Variations in the incidence of Eimeria species were observed during treatment with anticoccidial drugs. Repeated administration of the same agents resulted in changes in the spectrum; among other things, the number of mixed infections increased. Particularly so-called shuttle programmes using nicarbazin were found to be effective in suppressing coccidiosis.