Climatic Variables and the Transmission of Bacillary Dysentery: Any Differences Between Northern and Southern China?

Abstract

TM4-O-05 Introduction: The impact of climate change on food-borne diseases is far from clear. Few relevant studies have been conducted in China. Using disease surveillance data, this paper examines the relationship between climate variables and bacillary dysentery in different climatic areas in China. Methods: Jinan city of Shandong Province in northern China, with a temperate climate, and Baoan district of Shenzhen in southern China, with a subtropical climate, were chosen as study areas. Monthly notified bacillary dysentery cases were obtained from local Centers for Diseases Prevention and Control. Monthly meteorologic data, including maximum temperature, minimum temperature, rainfall, relative humidity, and air pressure, were collected from the Chinese Meteorologic Bureau. Spearman correlation analysis and seasonal Autoregressive Integrated Moving Average (ARIMA) model were performed to investigate the association between climatic variables and the incidence of bacillary dysentery in the 2 study areas. The effect of seasonality was taken into account. The hockey stick model was used to explore the threshold of the effect of temperatures. Results: The incidence of dysentery positively correlated with maximum temperature, minimum temperature, rainfall, humidity, and related negatively to air pressure in both cities with the lag effects from zero to 2 months. In the ARIMA models, the only significantly included climatic variables are maximum and minimum temperatures. Additionally, an order-2 autoregressive variable and a seasonal variable were significant in the northern city, whereas an order-1 autoregressive variable and no seasonal variable were significant in the southern city. The thresholds for the effects of maximum and minimum temperatures were 17°C and 8°C, respectively, in the northern city. No thresholds were detected in the southern city. Conclusions: Although there are different seasonal patterns in the distribution of bacillary dysentery, maximum and minimum temperatures affect the transmission of bacillary dysentery in both temperate and subtropical areas in China. Threshold temperatures in the northern city were detected, which may have policy implications for the disease control and prevention. However, no threshold was identified in the southern city, which could be due to its subtropical climate with relevant higher temperatures throughout the year.