Abstract
An epizootiological survey has been carried out on naturally occurring coccidiosis in Hartley guinea pigs (weight, 250g) purchased by the National Institute of Health, Tokyo during the period 1964 to 1982. Coccidial infections in breeding colonies of guinea pigs were observed very frequently in weaned animals but scarcely in adult and suckling animals. Oocysts of Eimeria caviae were detected in 53.8% of the 7, 162 fecal samples collected from transportation boxes and coccidiosis occurred in 39% of the 1, 461 dead or culled animals obtained during the routine one week quarantine period. In the period 1964 to 1971, particularly high rates of prevalence of oocysts, between 55-86%, and incidence of coccidiosis, between 55-76%, were observed. These rates were clearly reduced in the period 1972 to 1982, with a lower rate of isolation of oocysts ranging from 14-48% and les than 20% incidence of coccidiosis (except in 1981 and 1982) . The monthly fluctuation of occurrence rates of oocysts and clinical coccidiosis differed over the period of study. From 1964 to 1971, the high prevalence of oocysts was consistently observed accompanied by a bimodal pattern of incidence of coccidiosis in April (85 %) and October (78 %) . In the period 1972 to 1982, both parameters showed a single peak, for prevalence of oocysts in June (60.7%) and for incidence of coccidiosis in May (45 %) . Oocysts in feces disappeared in February and March and coccidiosis occurred irregularly in 1981 and 1982. Considering incidence in individual colonies, almost all colonies showed a high prevalence (70-100%) of isolation of oocysts and a high proportion (70-100%) of occurrence of coccidiosis in the period 1964 to 1971. Thereafter, coccidial infections and especially the outbreak of coccidiosis decreased. We conclude that since 1972 improved care and management of breeding colonies has probably resulted in a much lower prevalence of coccidial infection in weaned animals.
