Serological evidence of leptospirosis in patients with a clinical suspicion of dengue in the State of Ceará, Brazil

Dengue and leptospirosis are two febrile illnesses of great clinical and epidemiological importance in Brazil. Their significant degree of symptomatic similarity makes clinical diagnosis difficult. To diagnose leptospirosis differentially in patients with clinically suspected dengue. In this study, 86 patients with clinically suspected dengue underwent virological and serological diagnostic evaluations for dengue (reverse transcriptase polymerase chain reaction, NS1 immunochromatographic test, and NS1 enzyme-linked immunosorbent assay, ELISA), as well as tests to detect immunoglobulin M (IgM; IgM/IgG Rapid Test and IgM ELISA). The same patients were subsequently evaluated for leptospirosis using Rapid Test IgG/IgM (Bioeasy®) and Leptospira IgM ELISA (PanBio®). Of the 86 patients, 48 (55.8%) had positive results for dengue in at least one of the tests and five (7.35%) showed positive reactions for leptospirosis. During dengue epidemics, this disease may be misdiagnosed as other infections, including leptospirosis, when diagnosis is based on nonspecific clinical and laboratory criteria alone.