Etiology of Obscure Fever

Obscure fever is not an uncommon problem in Thailand. We studied 25 children with obscure fever admitted to Srinagarind (university) Hospital in Northeast Thailand. The etiology was identified in 52% of the cases: dengue (40%), leptospirosis (8%), and micrococcus septicemia (4%). Two cases with primary dengue infection developed dengue shock syndrome. The case with leptospirosis developed infection-associated, hemophagocytic syndrome. We found no cases of Japanese encephalitis, scrub typhus or murine typhus. days, without localizing signs. Informed consent was obtained from the parents and informed assent from the children. The inclusion criteria of a fever lasting more than 6 days was to try to exclude cases of dengue, which usually has a fever duration of 4.6 ± 1.8 days (Pancharoen et al, 2001). Immunocompromized patients or those with obvious signs and symptoms of a specific infection, such as profuse rhinorrhea, exudative tonsils, mucousy and/or bloody stools or urinary tract symptoms, were excluded. Clinical data and acute serum samples were collected when the patient satisfied the inclusion criteria. Convalescent serum samples were collected whenever possible, ideally 7-14 days following collection the of the acute serum sample, though the range was actually between 4 and 33 days. All of the serum samples were frozen at -70oC prior to assay. All of the serum samples were sent to the Regional Medical Science Center Khon Kaen, Ministry of Public Health, Thailand, where they were analyzed for evidence of dengue, Japanese encephalitis (JEV), Leptospira, O. tsutsugamushi and R. typhi infection.