title: Increased rainfall is associated with increased risk for legionellosis.
abstract: Legionnaires' disease (LD) is caused by Legionella species, most of which live in water. The Mid-Atlantic region experienced a sharp rise in LD in 2003 coinciding with a period of record-breaking rainfall. To investigate a possible relationship, we analysed the association between monthly legionellosis incidence and monthly rainfall totals from January 1990 to December 2003 in five Mid-Atlantic states. Using negative binomial model a 1-cm increase in rainfall was associated with a 2.6% (RR 1.026, 95% CI 1.012-1.040) increase in legionellosis incidence. The average monthly rainfall from May to September 1990-2002 was 10.4 cm compared to 15.7 cm from May to September 2003. This change in rainfall corresponds to an increased risk for legionellosis of approximately 14.6% (RR 1.146, 95% CI 1.067-1.231). Legionellosis incidence increased during periods of increased rainfall; identification of mechanisms that increase exposure and transmission of Legionella during rainfall might lead to opportunities for prevention.
authors.affiliation: Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, GA, USA. lauria_hicks@brown.edu
authors.forename: L A
authors.initials: LA
authors.lastname: Hicks
authors.forename: C E
authors.initials: CE
authors.lastname: Rose
authors.forename: B S
authors.initials: BS
authors.lastname: Fields
authors.forename: M L
authors.initials: ML
authors.lastname: Drees
authors.forename: J P
authors.initials: JP
authors.lastname: Engel
authors.forename: P R
authors.initials: PR
authors.lastname: Jenkins
authors.forename: B S
authors.initials: BS
authors.lastname: Rouse
authors.forename: D
authors.initials: D
authors.lastname: Blythe
authors.forename: A P
authors.initials: AP
authors.lastname: Khalifah
authors.forename: D R
authors.initials: DR
authors.lastname: Feikin
authors.forename: C G
authors.initials: CG
authors.lastname: Whitney
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D007876:Legionellosis / Q000209:etiology*; D008875:Middle Aged; D011891:Rain; D012307:Risk Factors; D013696:Temperature; D014871:Water Microbiology