Water Use And Giardiasis In Aucklanders: A Statistical and Spatial Analysis

Giardia is now one of the leading protozoal causes of human gastrointestinal illnesses. The World Health Organisation estimates around 200 million people are infected with this parasite. Over 2000 Giardia positive cases are reported in New Zealand annually and it is the second most common notifiable disease. Up to 41 percent of cases are notified from the Auckland region. The organism is ubiquitous and has been identified in the water supplies of 97 countries worldwide. The port of entry of the parasite is oro-faecal and water acts as an important vehicle for its spread. The current study investigated a modifiable risk factor for Giardia infection (drinking water use) and attempted to quantify the problem in Auckland in particular and New Zealand in general. The study involved 200 laboratory positive Giardia cases and 400 controls, selected from a randomised list of phone numbers, aged 15 years and over and had their contact number in the Auckland Telephone Book. Cases were referred by GPs and randomly selected controls were then identified for interview. The telephon