Introduction: 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.
Objective: To diagnose leptospirosis differentially in patients with clinically suspected dengue.
Materials and methods: 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®).
Results: 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.
Conclusion: During dengue epidemics, this disease may be misdiagnosed as other infections, including leptospirosis, when diagnosis is based on nonspecific clinical and laboratory criteria alone.