Giardiasis in Travelers: A Prospective Study

Stools of 139 asymptomatic students were examined by use of the formalin-ether concentration technique. Giardia lamblia was found in 12. Of the 49 who had never been outside Scandinavia, one harbored G. lamblia. Thus, endemic infestation is rare in Finland. Carriers were significantly more frequent among those who had traveled abroad. Nine of the 49 persons who had visited Leningrad harbored G. lamblia. Stool samples taken before and after travel from 60 visitors to Leningrad were examined. The incidence of infestation with G. lamblia was significantly greater after travel, which proved the implications of previous retrospective studies that the parasite is frequently acquired in Leningrad. Recovery of G. lamblia correlated positively with the use of tap water and the occurrence of symptoms.