Epidemiological and etiological investigation of a rare family cluster caused by severe fever with thrombocytopenia syndrome in Anhui Province in 2023

Abstract

Abstract Background Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne infectious disease discovered in the 21st century. Human-to-human transmission of the disease has been documented, but the mechanisms of transmission require further investigation. Methods Epidemiological investigations and genetic analyses of the patients were conducted, and a retrospective cohort study was performed to analyze potential risk factors for person-to-person transmission. Results According to epidemiologic investigations, 14 secondary cases had a clear history of exposure to blood and body fluids, and 3 secondary cases may have been exposed to aerosols in a poorly ventilated environment. Risk factor assessment revealed that the risk of SFTS was 6.778 times higher [RR = 6.778, 95%CI = 1.570-29.354] among those who had direct blood contact with the indicated patient compared to those who did not, and exposure to bloody secretions from the corpse was associated with a 12.800 times higher risk for SFTS [RR = 12.800, 95%CI = 1.479-110.789] compared to contact with the blood, bloody fluids, or secretions of living patients. Conclusions Contact with the blood of a deceased individual during funeral rites was associated with secondary cases of SFTS. The cluster outbreak is suspected to be due to person-to-person transmission of SFTSV, likely through direct contact with the blood of an SFTS patient, while the spread of aerosols in enclosed environments is also an undeniable mode of transmission.

Keywords

• Severe fever with thrombocytopenia syndrome
• Disease cluster
• Epidemiologic investigations