Inquérito soroepidemiológico de doenças febris agudas no Triângulo Mineiro: Leptospirose e febre maculosa

Abstract

Introduction: The correct diagnosis of several acute febrile illnesses represents a real challenge for healthcare professionals. There is a tendency to focus on diagnosing endemic diseases in the region, while less prevalent ones may go uninvestigated, potentially leading to underreporting of the less prevalent diseases, such as leptospirosis and spotted fever, causing setbacks to the health surveillance system. Objectives: To conduct a seroepidemiological survey for anti-leptospira, anti-Rickettsia rickettsii, and Rickettsia parkeri antibodies based on suspected dengue cases with non-reactive serology. Material and methods: For the serological analyses of leptospirosis, 449 serum samples were selected from patients with negative results for dengue in 2019, presenting clinical symptoms such as fever, headache, myalgia, and nausea. A rapid test was used for qualitative screening of specific IgM antibodies for Leptospira (Dual Path Platform - DPP Leptospirosis - Fiocruz), and reactive samples underwent microscopic agglutination test (MAT) analysis. For Rickettsia sp. analyses, 152 serum samples were selected that were also non-reactive for dengue and met the following criteria: collection time equal to or greater than 14 days, patients residing in rural and peri-urban areas, and professionals with occupational activities at higher risk of exposure. The samples were analyzed by indirect immunofluorescence assay (IFA). Results: Among the samples analyzed with DPP Leptospirosis, 26 tested positive (5.79%). In MAT, nine samples (17.31%) were reactive, with six of them also showing reactivity in DPP Leptospirosis. Regarding the analyses for Rickettsia rickettsii and Rickettsia parkeri, 29 samples (19.08%) showed reactivity at the 1:64 dilution for either of the analyzed strains. The samples reactive at the 1:64 dilution for Rickettsia rickettsii and Rickettsia parkeri represented 13.16% and 5.92%, respectively, of the total samples analyzed. Conclusion: The results found in this study showed reactivity for leptospires and rickettsial agents in patients who were suspected of dengue but who presented a negative laboratory diagnosis for this endemic arbovirus in the region. Such findings draw attention to the underreporting of acute febrile illnesses with a lower incidence in that area, and alert to the need for a syndromic diagnosis that includes these pathologies.