Murine and scrub typhus at Thai-Kampuchean border displaced persons camps

Rickettsial infections are considered a major cause of illness among inmates of Thai-Kampuchean border displaced persons camps. In the absence of sophisticated laboratory support, it had become common practice to treat patients with obscure fevers with tetracycline as a 'diagnostic' test for typhus. This study evaluated a group of 67 randomly selected camp inmates who presented with fever and had findings that indicated a specific diagnosis. Differential blood counts, malaria smears, hemoglobin determinations, blood cultures, dengue and Japanese encephalitis virus and rickettsial IgM and IgG antibody titers were determined. Patients were then treated with tetracycline and followed. They could be divided into six groups after data were analyzed. Those with no final diagnosis comprised 14 cases (21%), 4 patients (6%) were found to have dengue fever, 6 (9%) scrub typhus and 39 (58%) had murine (endemic) typhus. None of the bacterial blood cultures drawn from this group grew any organisms and no tick typhus or Japanese encephalitis was diagnosed. Analysis of symptoms and signs did not allow clinical differentiation between groups. All patients became afebrile and well within 1-5 days of starting tetracycline therapy. We conclude that rickettsial disease is a major health problem in the Thai-Kampuchean border camps. The incidence of murine typhus increased during the dry season and was more prevalent among males. The use of tetracycline as a 'therapeutic test' did not distinguish between rickettsial, viral and undiagnosed febrile diseases.