Objective:

To describe the epidemiological and clinical characteristics of an SFTS cluster in Shanghai, a nonendemic area of China, and assess the potential risk of healthcare-associated transmission.

Approach:

• Case definition: Suspected and laboratory-confirmed SFTS cases were defined according to the 2010 Guidelines for the Prevention and Control of Fever with Thrombocytopenia Syndrome.
• Epidemiological investigation: Investigators collected demographic and clinical data, living and environmental information, exposure histories, and activities before symptom onset.
• Sample collection and laboratory testing: Serum specimens from five patients and 15 environmental swabs from the intensive care unit were tested for SFTSV RNA. Patient serum was also tested for SFTSV-specific IgM and IgG antibodies.

Key Findings:

• Seven symptomatic individuals were identified: five family members and two healthcare workers. Two patients died.
• Four cases were laboratory-confirmed, one was classified as suspected, and two could not be definitively diagnosed because one had only an IgM-positive result and the other declined specimen collection.
• The index patient had performed outdoor cleaning in a densely vegetated area where SFTS cases had previously been reported. Subsequent infections were considered highly likely to have resulted from unprotected contact with the patient’s blood or bodily fluids.

Interpretation:

The cluster suggests family and healthcare-associated transmission of SFTSV from an imported case in Shanghai, including the first documented healthcare-associated cluster in the city.

Limitations:

• The index patient died before investigators could determine whether a tick bite or another exposure caused the initial infection.
• Tick exposure among some secondary cases could not be completely excluded, and one symptomatic family member declined specimen collection, preventing definitive diagnosis.

Conclusion:

The investigation underscores the need for greater clinical awareness and rigorous contact and aerosol precautions when caring for patients with unexplained fever and hemorrhagic manifestations, particularly those arriving from SFTS-endemic regions.