Short term effects of weather on hand, foot and mouth disease

• Published in: PloS one Vol. 6; no. 2; p. e16796
• Main Authors: Hii, Yien Ling, Rocklöv, Joacim, Ng, Nawi
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.02.2011; Public Library of Science (PLoS)
• Subjects: Analysis; Clinical medicine; Complications; Computer centers; Coxsackievirus; Coxsackievirus infections; Data processing; Disease Outbreaks; Disease prevention; Encephalitis; Enterovirus; enterovirus-71; Environmental conditions; epidemic; Epidemiology; Foot and mouth disease; Hand, Foot and Mouth Disease - epidemiology; Hand-foot-and-mouth disease; herpangina; Incidence; Infectious diseases; Maximum temperatures; Medical research; Medicine; Outbreaks; Poisson density functions; Public health; Rain; Rainfall; Regression analysis; Regression models; Risk; Risk assessment; Seasonal variations; singapore; Singapore - epidemiology; Statistical analysis; survival; taiwan; Temperature; Temperature effects; Time Factors; Time lag; Trends; Weather; Weather effects; Singapore; Sweden; Taiwan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0016796

Hand, foot, and mouth disease (HFMD) outbreaks leading to clinical and fatal complications have increased since late 1990s; especially in the Asia Pacific Region. Outbreaks of HFMD peaks in the warmer season of the year, but the underlying factors for this annual pattern and the reasons to the recent upsurge trend have not yet been established. This study analyzed the effect of short-term changes in weather on the incidence of HFMD in Singapore. The relative risks between weekly HFMD cases and temperature and rainfall were estimated for the period 2001-2008 using time series Poisson regression models allowing for over-dispersion. Smoothing was used to allow non-linear relationship between weather and weekly HFMD cases, and to adjust for seasonality and long-term time trend. Additionally, autocorrelation was controlled and weather was allowed to have a lagged effect on HFMD incidence up to 2 weeks. Weekly temperature and rainfall showed statistically significant association with HFMD incidence at time lag of 1-2 weeks. Every 1°C increases in maximum temperature above 32°C elevated the risk of HFMD incidence by 36% (95% CI = 1.341-1.389). Simultaneously, one mm increase of weekly cumulative rainfall below 75 mm increased the risk of HFMD by 0.3% (CI = 1.002-1.003). While above 75 mm the effect was opposite and each mm increases of rainfall decreased the incidence by 0.5% (CI = 0.995-0.996). We also found that a difference between minimum and maximum temperature greater than 7°C elevated the risk of HFMD by 41% (CI = 1.388-1.439). Our findings suggest a strong association between HFMD and weather. However, the exact reason for the association is yet to be studied. Information on maximum temperature above 32°C and moderate rainfall precede HFMD incidence could help to control and curb the up-surging trend of HFMD.