Increased rainfall is associated with increased risk for legionellosis.
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.
Hicks
L A
LA
Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, GA, USA. lauria_hicks@brown.edu
Rose
C E
CE
Fields
B S
BS
Drees
M L
ML
Engel
J P
JP
Jenkins
P R
PR
Rouse
B S
BS
Blythe
D
D
Khalifah
A P
AP
Feikin
D R
DR
Whitney
C G
CG
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