[Studies on the giardiasis as the zoonosis. II. Giardiasis in dogs and cats]

To obtain the basic data on the route of Giardia infection as zoonosis, we examined feces from 354 dogs and 34 cats for Giardia cysts and trophozoites and evaluated the detection rates. In addition, the feces of owners of the dogs infected with Giardia were examined. Giardia cysts and trophozoites were detected in 58 of the 354 dogs (16.4%) and 3 of the 34 cats (8.8%). Of the 61 animals from which cysts and trophozoites were isolated, 59 were purchased from the breeders and the other two animals had been kept for examinations in the research institute. None of the owners of the dogs had this infection. This result suggests that the possibility of human infection from contact with infected dogs or cats seems to be very low. However, attention should be paid to the possibility of cross-infection between men and animals, because it is not yet clear whether Giardia is strictly host-specific or not.