Successful experimental infections of a human volunteer and Mongolian gerbils with Giardia of animal origin.

A human volunteer and Mongolian gerbils were shown to be susceptible to infection with Giardia from a Gambian giant pouched rat. The course of infection and the pattern of cyst excretion, as well as the number of cysts in gerbils which were given the same inocula of Giardia, differed from the course of infection in humans. The latent period in gerbils was longer and the gerbils continually excreted numerous cysts, whereas excretion of cysts, in smaller numbers, by the volunteer was intermittent. Moderate clinical symptoms were noted in the volunteer, and the infection was confirmed by the development of anti-Giardia antibodies. The study demonstrated the zoonotic character of giardiasis and has important implications for the epidemiology of Giardia.