Aim: To obtain epidemiological information about giardiasis in Canterbury.
Method: From October 1990 general practitioners were requested to report laboratory confirmed cases. The first 100 cases were sent a questionnaire and also asked to provide the details of two persons to be controls.
Results: In the first nine months 109 cases were reported. Eighty four cases completed questionnaires and 51 were matched with controls. The overall reported attack rate was 4.0 per 10,000 population per year. The rate was highest for preschool children and young adults and in rural areas. There was a significant risk associated with having contact with sewage or travelling overseas and a marginal risk for drinking water outside Christchurch.
Conclusion: The results indicated that giardiasis was relatively common in Canterbury and confirmed that the major mechanisms of infection were probably the same as those previously identified overseas, namely person to person spread via faecal-oral transmission and the drinking of inadequately filtered water.