Environmental and Laboratorial Investigation of Two Potential Spotted-fever Group Rickettsioses Cases in a Non-endemic Area of Brazil

Abstract Objective: To describe two-rickettsiosis laboratory-positive cases, and their eco-epidemiology, in non-autochthonous area of Brazil, 2022. Methods: Case report study with environmental investigation, from May 1st to November 14th, 2022. Data collection occurred through interviews and health records; ectoparasites and dogs’ blood samples were collected, and spatial monitoring of a Rickettsia serologic reagent dog was performed. Software used: Epi Info 7.2.5.0, QGIS 3.16.6, Microsoft Excel® 365, GenBank, Google Earth 10.43.0.2 and Gaia GPS 2022.9. Results: The first (1st) case presented fever, myalgia, headache, lower limb rash, hepatosplenomegaly, renal alterations, and death after 18 days of hospitalization. The second (2nd) case manifested fever, edema, abdominal pain and intermittent pain in limbs for three months. The suspicion of the 2nd case was raised due to territorial link with the 1st case. None of them used antibiotics for the disease. Among common exposure factors were the circulation in the municipality's rural area; no visitation to endemic regions; no exposure to risk activities; and dogs from the area with access to the forest. The investigation resulted in identification of Amblyomma varium hosted by agent similar to Candidatus Rickettsia andeanae and Rickettsia amblyommatis; dogs’ blood serologically positive for Rickettsia; the monitored dog accessing the Atlantic Forest and human households. Conclusion: Although the data was not sufficient to set rickettsiae species involved, and if the human cases were genuinely Spotted Fever rickettsiosis, it is certain the necessity of a sensitive health surveillance to elucidate pathogenic rickettsiae species circulation in the area, its potential transmission biocycle and epidemiology.