Survey of severe fever with thrombocytopenia syndrome virus covert infection for healthy people in Henan Province, China

Abstract

BackgroundSevere fever with thrombocytopenia syndrome (SFTS) is a severe emerging disease, and its incidence has been increasing in recent years. A cross-sectional study was conducted for healthy people in high SFTS endemic areas of Henan province in 2016. MethodsThis study used stratified random sampling method and finally 14 natural villages were selected as the investigation site. The questionnaire survey and serum collection were carried out from April to May in 2016. All the serum samples were detected by SFTSV IgM and IgG antibodies by ELISA. Only positive samples of SFTSV IgM antibody need be tested SFTSV RNA and virus cultured. A month after the specimen collection, all persons positive for IgM antibody were followed up one by one to confirm whether he or she was recessive infection. Results1463 healthy persons were investigated in total. The average seropositive rates of SFTS virus specific IgG and IgM antibodies were 10.46% (153/1463) and 0.82% (12/1463), respectively. IgM antibody was positive in 12 individuals, and 6 of them SFTS virus RNA were also detected. In addition, 5 SFTS virus were isolated from the 6 SFTS virus RNA (+) individuals. By genomic sequencing and phylogenetic analysis, 5 new isolates from healthy crowd all belonged to groups A, which were similar to other isolates from SFTS patients. After one month, all people with SFTS virus IgM antibody had no illness or symptoms. ConclusionsThis study confirmed there is SFTS recessive infection in human, and it is the first report about SFTS virus isolation in healthy people. Author SummarySevere fever with thrombocytopenia syndrome (SFTS), a severe emerging infectious disease, was discovered in rural areas of China. The first SFTS case was found in Henan province, which has had the largest number of SFTS cases in China every year since the disease was discovered. However, as a high incidence area of SFTS in Henan province, the serum prevalence rate of the virus in healthy people is still not clear. Therefore, a cross-sectional survey was performed in high endemic areas and epidemic seasons in 2016. The results showed that the level of specific SFTS seroprevlence was relatively higher and possibility increasing. SFTS RNA were positive and SFTS virus was isolated from the specimens of healthy people. This study confirmed there is SFTS recessive infection in human, and it is the first report about SFTS virus isolation in healthy people.