Comparative studies on the pattern of infection with Giardia spp. in mongolian gerbils.

Mongolian gerbils (Meriones unguiculatus) were inoculated with known numbers of Giardia cysts isolated from humans, beavers and mice. The pattern of cyst release in the feces was studied for a period of 35 days. After a latent period of 5 days, animals infected with G. muris release cysts in their feces every day until day 14. Gerbils infected with human or beaver isolates released cysts in their feces intermittently for 30 days. These results indicated that the mode of cyst release in these animals was characteristic of the parasite, and was independent of the host. Mongolian gerbils acquire complete resistance upon homologous species challenge but demonstrate only partial protection when challenged with a different species of Giardia. We concluded that the Mongolian gerbil model could be useful in epidemiological studies for two reasons: it can be used for determination of cyst viability, and for the identification of the etiological agent.