Seroprevalence of antibodies against SFTS virus infection in farmers and animals, Jiangsu, China

Background Severe fever with thrombocytopenia syndrome (SFTS) is a newly identified viral zoonosis caused by a phlebovirus. Most reported SFTS cases are farmers living in rural areas. The seroprevalence of SFTS virus in farmers has not been investigated. The current knowledge of SFTS virus seroprevalence in animals, especially in wild animals, is still poor. Objectives To investigate SFTS virus seroprevalence among farmers and a variety of animal species. Study design SFTS virus antibodies in sera were determined using a double-antigen sandwich ELISA. Serum samples were collected from 2547 farmers and 2741 animals in 6 SFTS-endemic counties from March 2012 to February 2013 in Jiangsu province. The farmer participants aged from 15 to 90 years. All of them were interviewed using a structured questionnaire. The animals sampled included 6 domesticated animal species and 2 wild animal species. Results SFTSV antibodies were found in a total of 33 farmers (1.30%) and was more prevalent in males than in females (respectively 1.87% and 0.71%, P < 0.01). The mean age of seropositive farmers was 56.5 years and seroprevalence increased gradually with age. Seroprevalence in animal species were: goats (66.8%), cattle (28.2%), dogs (7.4%), pigs (4.7%), chickens (1.2%), geese (1.7%), rodents (4.4%) and hedgehogs (2.7%). Multiple variable logistic regression analysis showed that grazing, grass mowing, raising cattle, age, farm work time and tick bites were risk factors for SFTS virus infection among farmers. Conclusions SFTSV readily infects humans with farming-related exposures as well as numerous domestic and wild animals. Serological results further suggest that the virus circulates widely in Jiangsu province.