Epidemic characteristics and related factors of autumn-winter type scrub typhus in Shandong area,2010

Objective To explore the epidemic characteristics and related factors of scrub typhus and to provide evidence for prevention and control of the disease.Methods Based on Shandong Diseases Reporting Information System(SDIS),information on scrub typhus cases reported in 2010 were analyzed and a community-based 1 to 2 matched case-control study was carried out.Results The epidemic period of scrub typhus ranged from May to November and 74.10% of the cases occurred in October,the peak occurrence time.The age distribution of the cases was from 1 to 85 years,mainly at age of 50 to 70 years(45.82%).Male and female accounted for 48.21% and 51.79% of the cases.Farmer was the predominant occupation group among the cases(86.45%).There was no significant gender difference in occupation and age distribution(P＞0.05).Multi-variant analyses indicated that surroundings with weeds or crops,living at outskirts of village,bitten history by unknown insects,firewood or straws piled in yards,damp environment of living,unhealthy personal habits,and living in cottages were risk factors for scrub typhus,with the odds ratios of 2.815,2.250,4.500,2.100,5.788,1.943 and 4.049,respectively.Knowledge about rodents transmitting diseases was a preventive factor of the disease,with a population-attributive risk of 47.57%.Conclusion Farmers at middle and old age are the most susceptible population for scrub typhus; October is the peak occurrence period of the disease and its prevalence is related to several environmental factors.