Severe fever with thrombocytopenia syndrome can masquerade as hemorrhagic fever with renal syndrome

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging viral hemorrhagic fever with a high fatality rate and high frequency of person-to-person transmission and is caused by SFTSV, a tick-borne Phlebovirus. Because SFTS has similar clinical manifestations and epidemic characters (such as spatial and temporal distributions) with hemorrhagic fever with renal syndrome (HFRS) in China, we reason that SFTS patients might be misdiagnosed as HFRS. Methodology/principal findings: Acute-phase sera of 128 clinically diagnosed HFRS patients were retrospectively analyzed for Hantavirus IgM antibodies with ELISA. Hantavirus-negative patients’ sera were further analyzed for SFTSV IgM antibodies with ELISA. ELISA showed that 73 of 128 (57.0%) of clinically diagnosed HFRS patients were IgM antibody positive to Hantaviruses. Among the 55 Hantavirus-IgM negative patients, four (7.3%) were IgM antibody positive to SFTSV. The results indicated that the four SFTS patients were misdiagnosed as HFRS. The misdiagnosed SFTS patients had clinical manifestations common to HFRS and were unable to be differentiated from HFRS clinically. Conclusions: Our study showed that SFTS patients could be clinically misdiagnosed as HFRS. The misdiagnosis of SFTS as HFRS causes particular concern because it may increase the risk of death of SFTS patients and person-to-person transmission of SFTSV without proper care for and isolation of SFTS patients. Author summary: SFTS were clinically misdiagnosed as HFRS. It could cause particular concern in China. Physicians could not rely heavily on the exposure history. Both SFTS and HFRS patients are treated based on the clinical diagnosis in China. Laboratory confirmation of both diseases is not performed in clinical hospitals and the patients’ blood was usually submitted to a local or provincial center for disease control and prevention. In most cases the confirmation diagnosis is to provide retrospective information rather than to guide clinical therapy. Therefore, physicians need to carefully differentiate SFTS and HFRS patients because the fatality of SFTS is much higher than HFRS and SFTS is easily spread from person to person by contacting infected blood or even through aerosol.