Factors associated with acquiring giardiasis in British Columbia residents.

Giardia is the most frequently reported intestinal parasite in Canada. More than 2,000 cases are reported annually in British Columbia which exceeds the number of cases of either campylobacteriosis or salmonellosis. Since the different ways this parasite is spread in British Columbia have not been determined, our purpose was to investigate certain factors that might be associated with acquiring giardiasis in this province. Telephone interviews provided information from a group of infected persons and from a group of non-infected control subjects. Information obtained from these interviews was used to identify associated risk factors in this group of cases. If results of the study are generalized to the population-at-risk, they indicate that water (drinking and recreational) is an important vector for transmission of Giardia in British Columbia.