Non-linear effects of meteorological factors on plague epidemics in the plague foci of Subei and Sunan counties of Gansu Province / 中华地方病学杂志

ABSTRACT

Objective:To analyse the effects of meteorological factors on plague epidemic in Himalayana marmot plague natural foci in Subei and Sunan counties of Gansu Province. Methods:The surveillance data of plague from 1973 to 2016 in Himalayan marmot foci of Subei and Sunan counties (from Gansu Provincial Center for Disease Control and Prevention) and the meteorological factors (rainfall, temperature, relative humidity) of current, preceding first, second and third years (the first, second and third years before the reference year, from China Meteorological Data Sharing Service System) were collected. In order to build generalized additive model (GAM), the positive rate of plague was used as dependent variable while meteorological factors of the current, preceding first, second and third years were used as independent variables. The influence of meteorological factors on plague was quantitatively analyzed by using R2.3.2 software. Results:In 2006 - 2016, compared with 1974 - 1983, the average temperature in Subei rose by 0.99 ℃, the average relative humidity rose by 3.55%RH, and the average rainfall rose by 12.16 mm; in Sunan County, the average temperature rose by 1.00 ℃, the average relative humidity rose by 2.01%RH, and the average rainfall rose by 14.60 mm. From 1973 to 2016, 11 cases of human plague with 7 cases of dead (12 cases of attack) occurred in the investigated district. The average rainfall of the preceding third year of Subei rose every 1.00 mm within a certain range, the animal plague occurred rose by 0.40%. The average relative humidity of preceding second year of Subei rose every 1.00%RH within a certain range, animal plague occurred rose by 11.66%. The average rainfall of the preceding first year of Sunan rose every 1.00 mm within a certain range, the animal plague occurred rose by 1.32%. The average relative humidity of preceding third year of Sunan rose every 1.00%RH within a certain range, animal plague occurred rose by 11.96%. The average temperature of the preceding second year of Subei, Sunan rose every 1.00 ℃ within a certain range, animal plague rose 73.17%, 70.18%, respectively.Conclusions:The occurrence and prevalence of plague in Himalayana marmot are closely related to meteorological factors, and the temperature within a certain range (but not continuously) not only promotes the epidemic of plague, but also has a lag effect. In addition, the effects of different types of climate in the same foci on the prevalence of animal plague vary.