Classification and Molecular Epidemiology of Giardia

Abstract

Giardia intestinalis is a protozoan parasite found in the intestinal tract of humans and animals. Recent molecular studies show considerable genetic diversity among isolates from humans and animals, suggesting that this species is not a single species but is composed of multiple genotypes that have zoonotic potential or are host-adapted. Cross-infection studies using the isolates from different hosts and molecular epidemiological studies in endemic areas strongly support the zoonotic transmission of G. intestinalis. Molecular analysis of the isolates is therefore essential in order to reveal the sources of Giardia infection and thus develop appropriate countermeasures. In Japan, the molecular epidemiology of Giardia infection is as yet unclear as only a few isolates from humans and animals have been genotyped. This report finds that further studies are required for an understanding of the zoonotic significance and molecular epidemiology of Giardia infection in Japan.