Risk of giardiasis in Aucklanders: a case-control study.
BACKGROUND
Giardia is one of the leading protozoal causes of human gastrointestinal illnesses. It is prevalent in both developed and developing countries. Currently, giardiasis is the most commonly notified waterborne disease in New Zealand. The aim of the study was to identify potentially modifiable risk factors for Giardia infection in the adult population in Auckland.


METHODS
This case-control study involved 183 Giardia-positive cases and 336 randomly selected controls, aged between 15 and 64 years. Exposure information was collected retrospectively over the telephone for the 21 days preceding the date of onset of symptoms. Both univariate and multiple logistic regression analyses were carried out.


RESULTS
The majority of cases were in the 25-44-year age group and in the New Zealand European ethnic group. Housewives and nursing mothers were at significant risk of the disease (odds ratio (OR)=2.06; 95% CI=1.4-3.74), as were the occupational groups exposed to human wastes (OR=4.04, 95% CI=1.85-8.85). Consumption of drinking water from New Zealand supplies other than metropolitan mains supplies (OR=2.11, 95% CI=1.36-3.27) or from sources outside New Zealand (OR=7.97, 95% CI=4.20-15.12) represented a significantly higher risk, as did traveling (OR=7.57, 95% CI=4.03-14.23) and swimming in pools or fresh water at least once a week (OR=2.04, 95% CI= 1.33-3.12).


CONCLUSIONS
The study identified potentially modifiable risk factors for Giardia infection. These findings should be investigated further in different groups and settings to ensure better protection of the public health.
Hoque
M Ekramul
ME
New Zealand Environmental and Occupational Health Research Centre, University of Auckland, Auckland, New Zealand. e.hoque@auckland.ac.nz
Hope
Virginia T
VT
Kjellström
Tord
T
Scragg
Robert
R
Lay-Yee
Roy
R
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005243:Feces; D005260:Female; D005873:Giardiasis / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D007407:Interviews as Topic; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D016273:Occupational Exposure; D012307:Risk Factors; D013550:Swimming; D014195:Travel; D014881:Water Supply