Objective Investigate the source of infection, transmission routes of a cluster outbreak of SFTS(severe fever with thrombocytopenia syndrome) in Jingmen City, Hubei province in June 2024, and put forward prevention and control recommendations.

Methods In this study, case definitions were developed to search for cases, and then epidemiological investigations were conducted among cases and related persons, and the basic information, the onset and visit of the cases were described, and the source of infection and transmission route were analyzed through the above content. Finally, the monitoring of tick density and infection rate were carried out.

Results A total of 6 infected cases were found in the epidemic, including 1 case in the first generation (death), 5 cases in the second generation (3 cases have recovered from the onset and 2 cases have been implicitly infected). There were 4 males and 2 females, aged 27 to 65 years old. The incubation period of the secondary cases is 6 to 8 days; a total of 17 close contacts were determined for the index case, including personnel such as accompanying and transferring, organizing remains, and attending funeral, with secondary attack rate of 17.6% (3/17). Tick density monitoring results showed that the mean density of free-living ticks was 20 ticks/(flag 100ｍ·ｈ) and no parasitic ticks were collected. All of the ticks were identified as Haemaphysalis longicornis, negative for virus-specific nucleic acids.

Conclusion This epidemic is a clustered epidemic of human-to-human SFTS. The index case is considered to be infected by tick bites, and the secondary cases are considered to have the possibility of aerosol transmission during transportation, but contact transmission is not ruled out. It is recommended to strengthen the full-process closed-loop tracking management of severe patients who give up treatment, provide good connection and protection guidance for case transfer, strengthen training for high-risk groups such as drivers and nursing workers, strengthen disinfection of vehicles and items after transfer, and avoid human-to-human transmission during the transportation of cases.