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.

Legionnaires' disease in Europe: all quiet on the eastern front?

“…Thirdly, the disease's seasonality, with most cases reported during the warm season, is highly suggestive of an influence of environmental conditions on Legionnaires' disease incidence. This was already suggested by previous studies [28][29][30], even though the link between weather patterns and Legionnaires' disease incidence remains to be fully elicited. Finally, the urinary antigen test has now become by far the most used diagnostic test for Legionnaires' disease.…”

Microbiological and Clinical Studies of Legionellosis in 33 Patients with Cancer

“…During the 13 study years, we did notice yearly fluctuation of the isolation of these Legionella strains, and the reason behind this is under investigation. Rainfall is a reported risk factor for legionellosis (31,32). We previously noted that the clinical recovery of rapidly growing mycobacteria, also of an environmental origin, followed the seasonal rise and fall of rainfall in Houston (33).…”

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

“…The influence of changes to national water quality standards or adjustments in medical insurance reimbursement patterns is likely minimal (15,124). Interestingly, sporadic LD has been linked to higher-than-average atmospheric temperatures and increased rainfall (or humidity) in several studies, and while a mechanism is not clear, standing road water may play some part in infection (127)(128)(129)(130)(131)(132)(133)(134). A similar increase in the overall European LD incidence has also been documented over the past 20 years but with a possible plateau being reached in the late 2000s (120,135).…”