Most cases occur during the winter months in southern Alberta, but may develop any time cattle are crowded together. Coccidiosis in central Alberta tends to occur sporadically throughout the year.
Bovine coccidiosis is seen most frequently in calves that are six to twelve months of age.
Calves become infected when placed on pastures or lots contaminated by older cattle or other infected calves. Mature cattle may be infected when they are brought in from pastures and crowded into feedlots or barns. Life cycle of coccidia Bovine coccidia have stages both within the host animal as well as outside. Under proper conditions of temperature, moisture and oxygen, the oocyst develops within three to seven days to form a sporulated oocyst capable of infecting other cattle. At least nine species of coccidia occur in Alberta cattle, but only two, Eimeria zuernii and Eimeria bovis , are associated with the disease.