Impact of meteorological factors on scarlet fever incidence in Jiangsu province

  Objective  To investigate the influence of meteorological factors on the incidence of scarlet fever in Jiangsu province for providing evidences to the prevention and control of scarlet fever.

  Methods  We collected data on daily meteorological variables and reported scarlet fever incidents in Jiangsu province from January 1, 2010 to December 31, 2015. Distributed lag non-liner model was applied to explore associations between meteorological factors and scarlet fever incidence.

  Results  During the 6-year period, a total of 10 886 scarlet fever cases (6 748 males and 4 138 females) were registered in Jiangsu province, with a male-to-female ratio of 1.63:1 and an average annual incidence rate of 2.29 per 100 000 population. Spearman correlation analysis indicated that daily mean temperature and relative humidity were reversely correlated with scarlet fever (r_s = – 0.140, – 0.132, P < 0.05), while mean pressure and temperature range presented a positive correlation (r_s = 0.051, 0.172, P < 0.05). Distributed lag non-liner model revealed that the reported cases were increased at low temperature, and this positive effect was lasted for 10 days; however with the temperature rising, the risk of scarlet fever decreased. For the temperature varying within a small range, the risk of scarlet fever incidence was at a low level and long-term protective effect was also observed; as the temperature changing in a large range, the incidence of scarlet fever increased and the effect persisted for a long time. For relative humidity, the incidence of scarlet fever increased with dry climate, and the effect was also lasted for a long time; with very humid air, the protective effect was still detected with a 5-day lag.

  Conclusion  Several meteorological factors affect scarlet fever incidence with a non-linear relationship and different lag patterns.