ABSTRACT Spotted fever is a tick-borne rickettsiosis caused by several Rickettsia species—including R. rickettsii, R. parkeri, and others—with varying degrees of pathogenicity. Its nonspecific symptoms often lead to misdiagnosis such as dengue. This study investigated anti-R. rickettsii and R. parkeri antibodies in 152 patients with acute febrile illness who tested negative for dengue. Serological analysis using immunofluorescence assay found 29 reactive samples (19%) at a 1:64 dilution. Among them, 20.6% were male and 58.6% female, with an average age of 42.6 years. The average sample collection time totaled 14.6 days. Reactive samples included 13.1% for R. rickettsii and 5.9% for R. parkeri. These results suggest possible rickettsial infections in patients initially suspected of dengue.
Franco et al. (Thu,) studied this question.