Key differentiating features between scrub typhus and hemorrhagic fever with renal syndrome in northern China.

Both scrub typhus and hemorrhagic fever with renal syndrome (HFRS) are severely epidemic in northern China and often present with acute undifferentiated fever. To correctly distinguish the two diseases at an early stage, we collected and compared clinical and routine laboratory data of 46 patients with confirmed scrub typhus and 49 patients with confirmed HFRS presenting to the outpatient departments of three town hospitals in northern China. Most patients with HFRS but none of the patients with scrub typhus had hemorrhagic manifestations. Retro-orbital pain, lumbar back pain, flank tenderness, proteinuria, and occult blood in urine often occurred in patients with HFRS. However, skin eschar, regional lymphadenopathy, and maculopapular rash were more commonly found in patients with scrub typhus. In addition, platelet counts in patients with HFRS were significantly lower than in patients with scrub typhus. These findings will be useful for physicians to distinguish scrub typhus from HFRS.