Epidemiological characteristics of scrub typhus in high-incidence areas in the mainland of China, 2006–2018

ObjectiveTo analyze and compare epidemiological characteristics of scrub typhus in high-incidence areas in the mainland of China during 2006–2018.

MethodsSpatial analysis and statistical methods were used in this research.

ResultsTwelve provinces with high incidence of scrub typhus were divided into northern, southwestern and southern regions. A total of 146 653 scrub typhus cases were reported in these regions during 2006–2018. The incidence of scrub typhus showed a single peak in both northern region and southwestern region, mainly during October-November and during July-October, respectively. While the incidence of scrub typhus showed a bimodal peak in southern region, mainly during May-December. Scrub typhus cases increased and then decreased in northern region, and more cases in Anhui province and more affected counties (districts) in Jiangsu province had been reported since 2010. The reported scrub typhus cases and affected counties (districts) continued to increase in southwestern and southern regions. The reported scrub typhus cases in Yunnan province in southwestern region increased most rapidly, where the case number in 2018 was 28.91 times higher than that in 2006. The epidemic of scrub typhus was most serious in Guangdong province in southern region, where 139 counties (districts) were affected, and the case number in 2018 was 17.11 times higher than that in 2006. Spatial clustering of scrub typhus cases were observed. The cases in northern region mainly occurred in northern Anhui province, central-southern Shandong province and northeastern Jiangsu province. The cases in southwestern region were widely distributed in Yunnan province and eastern and southern Sichuan province. The cases in southern region were mainly distributed in Guangdong, Fujian provinces and eastern Guangxi autonomous region. Less cases occurred in males in all the regions, and most cases occurred in age groups 41–50, 51–60 and 61–70 years. The proportion of the cases in children aged 0–10 years was high in southwestern region. The cases were mainly farmers in all the regions, and the proportion of the cases in children outside child care settings was high in southwestern region.

ConclusionThe differences in epidemiological characteristics of scrub typhus existed among the regions with high scrub typhus incidences in the mainland of China. It is necessary to conduct the surveillance for scrub typhus in high incidence seasons in different regions and in population at high risk, and take preventive intervention measures to reduce the prevalence of scrub typhus.