[Occurrence of sick animals in conventional guinea pigs obtained from commercial breeders during 1964 to 1982]

A quarantine was performed on conventional Hartley guinea pigs free from Streptococcus zooepidemicus, Bordetella bronchiseptica and Salmonella spp., but infected with Eimeria caviae, which were purchased from twenty-five commercial breeders by the National Institute of Health. Physical examinations revealed an incidence of 0.88 per cent or 1,461 sick animals in 166, 050 guinea pigs quarantined during the period 1964 to 1982. The result obtained showed the following significant differences between the periods 1964 to 1971 and 1972 to 1982: Annual incidence of sick animals in the period 1972 to 1982 increased twice as many as 0.56 to 0.81 per cent during the 1964 to 1971, and monthly incidence showed bimodal occurrence at April and October in the former period but continual occurrence from November to April in the latter period. Major clinical signs in the former period were death and diarrhea, which occurred usually within a week after arrival of the guinea pigs at our institute and caused significant decrease of body weight, but those in the latter period were retarded growth and weakness which became detectable during 1-3 weeks after arrival of the animals. Discussions were made on possible reasons concerning the differences in incidence of sick animals during the two periods.