PURPOSE
To describe the first Q fever outbreak in Brazil and the long-term clinical and serological outcomes of affected individuals ten years after the outbreak.
METHODS
A follow-up investigation was conducted among patients involved in a Q fever outbreak that occurred in 2015 in a slaughterhouse in Barbosa, São Paulo State, Brazil. Clinical records from the acute phase were reviewed, and patients were reevaluated ten years later through clinical assessment, review of medical history, serological testing, and molecular analysis.
RESULTS
The outbreak affected 17 of 40 slaughterhouse workers (attack rate = 42.5%) and was likely associated with the inhalation of Coxiella burnetii during the slaughter of pregnant cows. Patients presented with prolonged fever, headache, myalgia, pneumonia, hepatitis, and hematuria; six required hospitalization. Ten years later, 14 patients were reevaluated. Of these, 10 developed complications compatible with chronic Q fever, including cardiac and respiratory disorders, as well as persistent fatigue. One woman experienced a premature birth after becoming pregnant following the outbreak. In 2025, one patient presented a phase I antibody endpoint titer of 1:1024 and a history of endocarditis, suggesting persistent infection.
CONCLUSION
This study provides a unique description of the long-term clinical and serological outcomes of workers involved in the first documented Q fever outbreak in Brazil and emphasizes the importance of post-outbreak surveillance and prolonged clinical follow-up.
D. A. França, I. S. Silito, Matheus Pasini-Martins et al.· Infection· 0 citations
Q fever, caused by Coxiella burnetii, is an underdiagnosed zoonosis in Brazil due to its non-specific clinical presentation and limited diagnostic capacity. This study investigated the molecular detection of C. burnetii in serum samples from patients with acute febrile illness initially suspected of dengue in 34 municipalities of São Paulo State, Brazil. A total of 300 serum samples collected over a three-year period from patients with suspected dengue fever were analyzed. Only samples obtained from patients presenting with up to seven days of febrile illness were included. All samples tested negative for dengue, leptospirosis, and brucellosis and were analyzed by real-time PCR targeting the IS1111 gene. C. burnetii DNA was detected in 1.3% (4/300) of the samples (95%CI: 0.37%-3.35%), compatible with recent infection during the early symptomatic phase. This study represents the second report of molecular detection of C. burnetii in patients with acute febrile syndrome in Brazil and the first one in São Paulo State. Previous serological studies indicate widespread exposure to the pathogen, highlighting the complementary roles of molecular and serological approaches. These findings support the inclusion of Q fever in the differential diagnosis of undifferentiated febrile illnesses and suggest that One Health-oriented surveillance strategies may help reduce underdiagnosis in Brazil, although further studies with larger sample sizes are needed to confirm this recommendation.
M. S. Mioni, Danilo Alves de França, Célio Valério de Jesus Mangueze et al.· Acta Tropica· 0 citations
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