Association of Melioidosis Incidence with Rainfall and Humidity, Singapore, 2003–2012 - Volume 21, Number 1—January 2015 - Emerging Infectious Disease journal - CDC

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Association of Melioidosis Incidence with Rainfall and Humidity, Singapore, 2003–2012 - Volume 21, Number 1—January 2015 - Emerging Infectious Disease journal - CDC

Volume 21, Number 1—January 2015

Dispatch

Association of Melioidosis Incidence with Rainfall and Humidity, Singapore, 2003–2012

On This Page

• The Study
• Conclusions
• Suggested Citation

Figures

• Figure

Tables

• Table 1
• Table 2

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Xiang Liu1, Long Pang1, Siew Hoon Sim, Kee Tai Goh, Sharada Ravikumar, Mar Soe Win, Gladys Tan, Alex Richard Cook, Dale Fisher, and Louis Yi Ann Chai 

Author affiliations: National University Health System University Medicine Cluster, Singapore (X. Liu, S. Ravikumar, M.S. Win, D. Fisher, L.Y.A. Chai); National University of Singapore and National University Health System Saw Swee Hock School of Public Health, Singapore (L. Pang, K.T. Goh, A.R. Cook); Defence Medical and Environmental Research Institute, Singapore (S.H. Sim, G. Tan); Ministry of Health, Singapore (K.T. Goh); National University of Singapore Yale-NUS College, Singapore (A.R. Cook); National University of Singapore Yong Loo Lin School of Medicine, Singapore (D. Fisher)

Suggested citation for this article

Abstract

Soil has been considered the natural reservoir for the bacterium Burkholderia pseudomallei, which causes melioidosis. We examined 550 melioidosis cases that occurred during a 10-year period in the highly urbanized city of Singapore, where soil exposure is rare, and found that rainfall and humidity levels were associated with disease incidence.

The gram-negative, saprophytic bacillus Burkholderia pseudomallei, which causes melioidosis, is endemic in northern Australia and Southeast Asia countries such as Thailand, Malaysia, and Singapore (1). Soil has traditionally been described as the natural reservoir of B. pseudomallei (hence the synonym “soil bacteria”) (2,3). Symptoms and signs of melioidosis can be mild, but severe manifestations such as bacteremia, organ abscesses, and severe pneumonia can lead to high death rates (4).

Two reports from northern Australia and northeastern Thailand, both conducted in predominantly rural areas, found an increase in melioidosis cases after heavy rainfall or extreme weather events such as tropical storms or monsoons (5,6). In Singapore, however, the occurrence of melioidosis in association with climatic variations has not been extensively studied. Geographically, Singapore has an urbanization rate of 100%, in contrast to northeastern Thailand (34%) and northern Australia (55%) (7,8). Because soil is the presumptive reservoir for B. pseudomallei, exposure may be less common in an extensively developed, urban setting such as Singapore, but other environmental factors, such as humidity and temperature, might also influence the pathogenicity of B. pseudomallei. We investigated 550 cases of melioidosis that occurred during a 10-year period in Singapore to determine if climatic factors might be related to the epidemiology of this disease in an urban setting.

Ms. Liu is a medical student at Duke-NUS Medical School. Her research interests are infectious diseases and immunology.

References

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Figure

• Figure. Total monthly rainfall (mm), average monthly humidity (%), and average monthly temperature (°C) compared with melioidosis case numbers, Singapore, 2003–2012. Cases are listed by date of illness onset.

Tables

• Table 1. Melioidosis case distribution by year, Singapore, 2003–2012
• Table 2. Temporal association of rainfall, humidity, and temperature with melioidosis cases, Singapore, 2003–2012

Suggested citation for this article: Liu X, Pang L, Sim SH, Goh KT, Ravikumar S, Win MS, et al. Association of melioidosis incidence with rainfall and humidity, Singapore, 2003–2012. Emerg Infect Dis. 2015 Jan [date cited]. http://dx.doi.org/10.3201/eid2101.140042

DOI: 10.3201/eid2101.140042

1These authors contributed equally to this article.