An epizootic form of Tyzzer's disease in a rat colony

An epizootic form of Tyzzer's disease was experienced in a rearing facility of laboratory rats with an infectivity and morbidity of 36 to 80% and 5 to 30%, respectively. With liver tissue from an affected rat, a spore-forming causative agent was successfully transmitted to other rats by oral inoculation in association with cortisone, producing 10(6) to 10(7) spores/g liver tissue.