Nappy handling and risk of giardiasis.

We did a case-control study to identify modifiable risk factors for giardiasis in people aged 15-64 years living in Auckland, New Zealand. 183 patients with stool-positive Giardia spp referred to community laboratories were compared with 336 age-matched controls identified randomly from the Auckland telephone book. Exposure information for the previous 3 weeks was obtained retrospectively by telephone. Nappy changing was associated with a four-fold increased risk of infection after controlling for other confounders. We conclude that children wearing nappies could be an important source of giardia infection in the community.