Nonlinear and Threshold Effect of Meteorological Factors on Japanese Encephalitis Transmission in Southwestern China

Abstract

Although previous studies have reported that meteorological factors might affect the risk of Japanese encephalitis (JE), the relationship between meteorological factors and JE remains unclear. This study aimed to evaluate the relationship between meteorological factors and JE and identify the threshold temperature. Daily meteorological data and JE surveillance data in Dazhou, Sichuan, were collected for the study period from 2005 to 2012 (restricting to May-October because of the seasonal distribution of JE). A distributed lag nonlinear model was used to analyze the lagged and cumulative effect of daily average temperature and daily rainfall on JE transmission. A total of 622 JE cases were reported over the study period. We found JE was positively associated with daily average temperature and daily rainfall with a 25-day lag and 30-day lag, respectively. The threshold value of the daily average temperature is 20°C. Each 5°C increase over the threshold would lead to a 13% (95% CI: 1-17.3%) increase in JE. Using 0 mm as the reference, a daily rainfall of 100 mm would lead to a 132% (95% CI: 73-311%) increase in the risk of JE. Japanese encephalitis is climate-sensitive; meteorological factors should be taken into account for the future prevention and control measure making, especially in a warm and rainy weather condition.

Scoping review of Japanese encephalitis virus transmission models

“…According to the model outputs, vector carrying capacity, weather variations, human-induced environmental discharges, and geographic location significantly impact vector and animalreservoir abundance. Geographic and temporal variations have also been incorporated in other models to understand variations in mosquito-borne diseases (Caldwell et al 2021), and human JE cases have been linked to changes in meteorological factors such as daily rainfall (Liu et al 2020). Models incorporating environmental drivers of JEV transmission, particularly climate features, might more accurately predict JE occurrence.…”

Climate Change and Vector-Borne Diseases in China: A Review of Evidence and Implications for Risk Management

“…China is one of the most vulnerable countries with respect to climate change [11]. Many studies have found the significant positive relationship between weather conditions and vector-borne diseases in China, including the effects of meteorological factors, such as temperature, precipitation, humidity, wind speed [12][13][14][15][16][17], and extreme weather events (e.g., extremely high temperatures, extremely high rainfall, and tropical cyclones) [18][19][20][21][22][23][24]. The 2020 China Report of the Lancet Countdown on Health and Climate Change showed that China's climate suitability for mosquito-borne dengue fever has increased by 37% in the past half century [25].…”