Molecular identification of severe fever with thrombocytopenia syndrome viruses from tick and bitten patient in Southeast China

BACKGROUND: Severe fever and thrombocytopenia bunyavirus (SFTSV) infection causes severe fever and thrombocytopenia syndrome with high mortality. It is extremely rare that a transmitting tick can be directly captured in bite wounds, and that SFTSV can be isolated from both the captured tick and patient’s serum to establish a solid pathogen diagnosis. CASE PRESENTATION: We report a case infected with severe fever and thrombocytopenia bunyavirus. The 69-year-old male patient presented with fever and tenderness on two lymph nodes in the right groin. A visible tick bite mark appeared on right upper quadrant of the patient’s abdomen, and a live tick was captured in the bite wound upon physical examination. The virus was detected in both the blood of the patient and in the tick that stayed in the bite wound for 7 days. The phylogenetic analysis indicated that the SFTSV isolated from the tick and the patient’s serum sample belonged to type B, in which the L/S segment of these two isolates shared 100% homology, while the M segment had 99.9% homology. The bitten patient was given various supportive care, but eventually died of multiple organ failure. CONCLUSION: The present case provides strong evidence of SFTSV transmission from H. longicornis to humans, and suggests that direct cross-species transmission can occur without additional intermediate hosts.