Serological Diagnosis of Scrub Typhus by Indirect Immunofluorescence

SummaryThe indirect fluorescent antibody test, in which dilutions of sera from patients with scrub typhus were tested on smears of Rickettsia tsutsugamushi, gave results which were serologically diagnostic of the disease in each instance. Non-specific reactions did not occur when the scrub typhus sera were exposed to antigens of other species of Rickettsia. Likewise, there was no reaction between R. tsutsugamushi smears and sera from other rickettsial infections, or with sera from patients with Proteus OXK agglutinins of non-rickettsial origin with one exception, i.e., a case of leptospirosis from Puerto Rico.