The etiology of acute pyrexia of unknown origin in children after a flood.

Acute pyrexia of unknown origin (PUO) is a major public health problem in Thailand. We studied the etiology of 180 cases of acute PUO in children after a sudden severe flood in Hat Yai city in 2000. Dengue infection and leptospirosis accounted for more than half of the total cases. Dengue hemorrhagic fever was the most common (29.4%) followed by leptospirosis (27.2%) and scrub typhus infection (1.1%). Five serovars of leptospires were involved in this study. Leptospira interrogans bataviae was the most common (86.5%). Acute serum antibody testing could detect only 52.8% and 40.8% of dengue and leptospirosis cases, respectively. This study showed both should be included in the presumptive diagnosis of acute PUO in patients after flooding.