Risk factors for sporadic giardiasis: a case-control study in southwestern England.
To investigate risk factors for sporadic infection with Giardia lamblia acquired in the United Kingdom, we conducted a matched case-control study in southwest England in 1998 and 1999. Response rates to a postal questionnaire were 84% (232/276) for cases and 69% (574/828) for controls. In multivariable analysis, swallowing water while swimming (p<0.0001, odds ratio [OR] 6.2, 95% confidence intervals [CI] 2.3 to 16.6), recreational fresh water contact (p=0.001, OR 5.5, 95% CI 1.9 to 15.9), drinking treated tap water (p<0.0001, OR 1.3, 95% CI 1.1 to 1.5 for each additional glass per day), and eating lettuce (pç=0.01, OR 2.2, 95% CI 1.2 to 4.3) had positive and independent associations with infection. Although case-control studies are prone to bias and the risk of Giardia infection is minimized by water treatment processes, the possibility that treated tap water is a source of sporadic giardiasis warrants further investigation.
Stuart
James M
JM
PHLS Communicable Disease Surveillance Centre (Southwest), Gloucester, UK. jstuart@phls.org.uk
Orr
Hilary J
HJ
Warburton
Fiona G
FG
Jeyakanth
Suganthiny
S
Pugh
Carolyn
C
Morris
Ian
I
Sarangi
Joyshri
J
Nichols
Gordon
G
D000818:Animals; D016022:Case-Control Studies; D003967:Diarrhea / Q000473:pathology; D004326:Drinking; D004739:England / Q000453:epidemiology; D016829:Giardia lamblia / Q000254:growth & development; D005873:Giardiasis / Q000453:epidemiology*; D006801:Humans; D016017:Odds Ratio; D012307:Risk Factors