Orientia tsutsugamushi in peripheral white blood cells of patients with acute scrub typhus

Scrub typhus, caused by Orientia tsutsugamushi, is an acute illness that occurs in many parts of Asia. Clinical manifestations range from inapparent to organ failure. Organisms disseminate from the skin to target organs, suggesting that they may enter the peripheral circulation. Here, peripheral blood cell smears from patients with acute scrub typhus were obtained before treatment and for 2 days after treatment and reacted with antibodies specific for O. tsutsugamushi. White blood cells from 3 of 7 patients with acute scrub typhus stained positively for O. tsutsugamushi. Cells containing O. tsutsugamushi were mononuclear and were detected on each day of sampling. The presence of O. tsutsugamushi in peripheral white blood cells of patients with acute scrub typhus is a new finding with clinical and pathogenic implications.