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In the north of Caldas, Colombia, febrile syndromes with positive Weil-Felix reactions have been reported as Murine typhus to the national health authorities. We used indirect immunofluorescence assay (IFA) of serial paired samples to confirm the diagnosis of murine typhus in 14 of 120 patients with a compatible febrile syndrome.

Rickettsia typhi is an intracellular obligate α-proteobacteria that primarily infects the vascular endothelium and causes murine or endemic typhus. Together with the agent of epidemic typhus, R. prowazekii, they are the exclusive members of the typhus group rickettsiae. R. typhi exists in nature in an enzootic cycle involving rodents and their ectoparasites. It is transmitted to humans mainly by Xenopsylla cheopis, the Oriental rat flea, although other species of fleas, as well as lice and mites, have occasionally been implicated. 1 Indeed, murine typhus is more prevalent in rat-infested locations. 2 The disease presents with initial non-specific “flu-like” symptoms and, although it is rarely lethal, it is incapacitating. Murine typhus in Colombia has not been previously reported in the international literature. However, it is frequently suspected throughout the north of Caldas province, Colombia, and “confirmed” with a positive Weil Felix reaction (agglutination of Proteus vulgaris OX19), a test of low specificity and sensitivity due to the use of a non-rickettsial antigen. 3 The objectives of this study were: 1) to confirm the presence of murine typhus as a cause of fever in this area of Colombia through the use of the gold standard serological test (indirect immunofluorescence assay [IFA]); and 2) to characterize the positive population …