Study on the lag effect of meteorological factors on the incidence of hand, foot and mouth disease in Ningbo, China, 2014—2019

Objective To analyze the relationship between daily mean air temperature in Ningbo, China and the incidence of hand, foot and mouth disease, and its lag effect.

Methods An analysis was conducted on the daily incidence of hand, foot and mouth disease in Ningbo from 2014 to 2019, along with meteorological data from the same period. A distributed lag non-linear model (DLNM) was used to assess the lag effect of air temperature on the incidence of hand, foot and mouth disease.

Results From 2014 to 2019, the incidence of hand, foot and mouth disease in Ningbo showed two peaks: a major peak usually occurred from late spring to summer (April to July), and a minor peak typically appeared from late autumn to winter (November to February of the following year). Among patients aged 1 year and older, the incidence decreased with increasing age. The incidence of hand, foot and mouth disease in Ningbo was positively correlated with air temperature, atmospheric pressure, and relative humidity, with correlation coefficients of 0.512, 0.490 and 0.072, respectively (all P < 0.01). The DLNM results showed that the curve of the overall effect of daily mean air temperature on the incidence of hand, foot and mouth disease had an M-shaped distribution. At the maximum lag day (day 14), the incidence reached its highest when the daily mean temperature was 25.8 ℃ (risk ratio=2.06, 95% confidence interval: 1.82-2.34).

Conclusion The daily mean temperature in Ningbo has a lag effect on the incidence of hand, foot and mouth disease, and the lag effect of high temperature lasts longer than that of low temperatures.