Different responses of weather factors on hand, foot and mouth disease in three different climate areas of Gansu, China

Abstract

Background: To determine the linear and non-linear interacting relationships between weather factors and hand, foot and mouth disease (HFMD) in children in Gansu, China, and gain further traction as an early warning signal based on weather variability for HFMD transmission.

Method: Weekly HFMD cases aged less than 15 and meteorological information from 2010 to 2014 in Jiuquan, Lanzhou and Tianshu, Gansu, China were collected. Generalized linear regression models (GLM) with Poisson link and classification and regression trees (CART) were employed to determine the combined and interactive relationship of weather factors and HFMD in both linear and non-linear ways.

Results: GLM suggested an increase in weekly HFMD of 5.9% [95% confidence interval (CI): 5.4%, 6.5%] in Tianshui, 2.8% [2.5%, 3.1%] in Lanzhou and 1.8% [1.4%, 2.2%] in Jiuquan in association with a 1 °C increase in average temperature, respectively. And 1% increase of relative humidity could increase weekly HFMD of 2.47% [2.23%, 2.71%] in Lanzhou and 1.11% [0.72%, 1.51%] in Tianshui. CART revealed that average temperature and relative humidity were the first two important determinants, and their threshold values for average temperature deceased from 20 °C of Jiuquan to 16 °C in Tianshui; and for relative humidity, threshold values increased from 38% of Jiuquan to 65% of Tianshui.

Conclusion: Average temperature was the primary weather factor in three areas, more sensitive in southeast Tianshui, compared with northwest Jiuquan; Relative humidity's effect on HFMD showed a non-linear interacting relationship with average temperature.

Keywords: Classification and regression tree; Climate change; Generalized linear model; Hand, foot and mouth disease.

Fig. 1

The study areas and their location in Gansu province and China. This figure was generated using ArcGIS software version 10.0 (ESRI, USA)

Fig. 2

Sequence chart of weekly HFMD and weather factors among three study areas in 2010–2014. AT: temperature; MaxT: maximum temperature; MinT: minimum temperature; TD: temperature difference; RH: relative humidity; RF: rainfall

Fig. 3

Scatter plot of weekly HFMD incidence and weather factors among three study areas in 2010–2014. A = AT: temperature; B = MaxT: maximum temperature; C = MinT: minimum temperature; D = TD: temperature difference; E = RH: relative humidity; F = RF: rainfall

Fig. 4

Cross-correlation analysis between weekly HFMD and weather factors among three study areas in 2010–2014. AT: temperature; MaxT: maximum temperature; MinT: minimum temperature; TD: temperature difference; RH: relative humidity; RF: rainfall. CCF: cross correlation function

Fig. 5

Relative risks of moving average of weather factors on HFMD among three study areas in 2010–2014. A = AT: temperature; B = MaxT: maximum temperature; C = MinT: minimum temperature; D = TD: temperature difference; E = RH: relative humidity; F = RF: rainfall. RR: relative risk

Fig. 6

CART modeling the relationship of weekly HFMD incidence and weather factors in 2010–2014. AT: temperature; MaxT: maximum temperature; MinT: minimum temperature; TD: temperature difference; RH: relative humidity; RF: rainfall. MA: moving average