Severe fever with thrombocytopenia syndrome presenting as hemophagocytic syndrome: two case reports

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that was first reported in China in 2011. However, it is now endemic in Japan, and the SFTS viruses in Japan and China have evolved independently. Its fatality rate is 26.5 % in Japan, and the viral load is related to morbidity.

We encountered two patients with SFTS. Case 1 is a 72-year-old woman who visited our hospital owing to severe fatigue, diarrhea, and nausea. Her consciousness level score on the Glasgow Coma Scale was 14 points, and her serum lactate dehydrogenase level was 646 IU/L. Case 2 is an 82-year-old woman who visited our hospital owing to diarrhea and general fatigue. Her consciousness level score on the Glasgow Coma Scale was 11 points, and her serum lactate dehydrogenase level was 935 IU/L.

Both patients had hemophagocytic syndrome and presented with similar symptoms. Although both were treated with similar drug regimens, their clinical courses were different: after treatment, the 72-year-old woman survived whereas the 82-year-old woman died. In addition to age, the two patients differed in terms of time between symptom onset and treatment initiation, consciousness level, viral load, and extent of elevation of liver enzyme levels.

The viral load, which is a predictor of morbidity, was associated with the level of consciousness and the serum lactate dehydrogenase level, both of which might be useful for predicting death in patients with SFTS.