To the knowledge of the common hamster (Cricetus cricetus Linné, 1758; Rodentia) as host of leptospirosis in Czechoslovakia.

A total of 1288 hamsters (Cricetus cricetus), coming from two regions of Czechoslovakia, were serologically investigated on the presence of leptospirosis. In 1114 hamsters from eastern Slovakia, where an outbreak occurred and local populations lived quite atypically, there was 31.8% positivity, in 174 animals from central Moravia, where the populations were at higher levels but lived normally, the positivity amounted to 17.2%. The serological positivity increases proportionately to the weight, i.e. to the age of the animals. The serovar grippotyphosa was dominant in them (29.6% of examined hamsters), while 6.0% were positive for L. pomona, 1.0% for serovars from the serogroup Sejroe, 0.2% for L. sorex-jalna and L. bataviae respectively, and 0.1% for L. bratislava. The hamsters from central Moravia were positive only for the serovar grippotyphosa. Antibodies in lower titres against L. pomona, having the character of coagglutinations, were simultaneously detected in some hamsters positive for L. grippotyphosa. In Czechoslovakia the common hamster is one of the potential hosts of L. grippotyphosa, its importance increasing during severe outbreaks, when the incidence of infection with L. grippotyphosa in hamster populations increases and the animals inhabit most varied types of biotopes and transfer to synanthropic way of life.