Spatiotemporal distribution of brucellosis in China, 2011−2020, enlightenment to prevention and control of brucellosis in field training of troops

  Objective  To analyze the spatiotemporal distribution of brucellosis in China from 2011 to 2020 and provide the evidence for the prevention and control measures of brucellosis in field training of troops.

  Methods  The incidence data of brucellosis were downloaded from Chinese Center for Disease Prevention and Control. The monthly case numbers during 2011–2020 were collected. Circle distribution method was used to identify the incidence peak day and peak period of brucellosis, and Joinpoint regression analysis was used to identify the long-term trend of annual and monthly incidence and evaluate the long-term trend and annual percent change (APC) of the disease . The spatial distribution characteristics of brucellosis in eastern, southern, western, northern and central China were analyzed.

  Results  The average incidence of brucellosis was 3.52/100 000 in China from 2011 to 2020. The incidence trend of brucellosis showed no obvious change (APC=−2.12%, P=5.589). The monthly incidence increased significantly from January to May (APC=34.38%, P=0.006), but decreased significantly from May to December (APC=−11.66%), the difference was significant (P=0.001). The obvious seasonality of brucellosis was observed from 2011 to 2020, brucellosis occurred all the year round, however, the obvious peak day and peak period were observed (P<0.001), but varied from year to year (F=332.03, P<0.001). The annual peak day was 26^th June, and the peak period was from 21^st March to 2^nd October. The case number was highest in northern China, followed by central, eastern, southern and eastern China. The case number of brucellosis in Inner Mongolia (78 646 cases) and Heilongjiang (45 132 cases) in the northern China ranked top two, followed by that in Shanxi (44 155 cases) in central China and Xinjiang (42 357 cases) in western China.

  Conclusion  The incidence of brucellosis was high in northern and central China. The peak day was 26^th June, and the peak period was from 21^st March to 2^nd October. Troops should pay attention to the prevention and control of brucellosis in field training in the areas with high-incidence of the disease, especially in the incidence peak period. .