title: Outbreak of giardiasis associated with a community drinking-water source.
abstract: Giardiasis is a common waterborne gastrointestinal illness. In 2007, a community giardiasis outbreak occurred in New Hampshire, USA. We conducted a cohort study to identify risk factors for giardiasis, and stool and environmental samples were analysed. Consuming tap water was significantly associated with illness (risk ratio 4.7, 95% confidence interval 1.5-14.4). Drinking-water samples were coliform-contaminated and a suspect Giardia cyst was identified in a home water filter. One well was coliform-contaminated, and testing indicated that it was potentially under the influence of surface water. The well was located 12.5 m from a Giardia-contaminated brook, although the genotype differed from clinical specimens. Local water regulations require well placement at least 15 m from surface water. This outbreak, which caused illness in 31 persons, represents the largest community drinking-water-associated giardiasis outbreak in the USA in 10 years. Adherence to well placement regulations might have prevented this outbreak.
authors.affiliation: New Hampshire Department of Health and Human Services, Concord, NH 03301-6504, USA. erdaly@dhhs.state.nh.us
authors.forename: E R
authors.initials: ER
authors.lastname: Daly
authors.forename: S J
authors.initials: SJ
authors.lastname: Roy
authors.forename: D D
authors.initials: DD
authors.lastname: Blaney
authors.forename: J S
authors.initials: JS
authors.lastname: Manning
authors.forename: V R
authors.initials: VR
authors.lastname: Hill
authors.forename: L
authors.initials: L
authors.lastname: Xiao
authors.forename: J W
authors.initials: JW
authors.lastname: Stull
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks; D004755:Enterobacteriaceae / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D005872:Giardia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D005873:Giardiasis / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009513:New Hampshire / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014867:Water / Q000469:parasitology*; D055815:Young Adult
chemical_list: D016054:DNA, Protozoan; D014867:Water