Q fever outbreak in a slaughterhouse in Brazil: retrospective assessment of long-term complications ten years later
1
Department of Preventive Veterinary Medicine and Animal Health, University of São Paulo, São Paulo, Brazil
2
Department of Health Surveillance, Municipal Health Secretariat, Barbosa, Brazil
3
Adolfo Lutz Institute, Vector-Borne Diseases Center, São Paulo, Brazil
Popul. Med. 2026;8(Supplement Supplement 1):A612
ABSTRACT
BACKGROUND:
Q fever is a neglected zoonosis and is rarely considered in the differential diagnosis of acute febrile illness1. The first Q fever outbreak in Brazil occurred in 2015 among slaughterhouse workers in the São Paulo state. This study aimed to report the outbreak and to retrospectively assess the long-term clinical and serological outcomes of affected workers ten years later.
METHODS:
In 2015, paired serum samples from slaughterhouse workers were tested by indirect immunofluorescence assay (IFA), and Q fever was confirmed by a fourfold rise in Coxiella burnetii antibody titers2. Molecular investigation was performed using polymerase chain reaction (PCR)3. In 2025, workers were re-evaluated through structured questionnaires addressing workplace conditions, clinical manifestations, and long-term complications. Medical records were reviewed, and current serum and whole blood samples were analyzed by IFA and PCR, respectively, to assess the present serological and molecular status.
RESULTS:
During 2015, 17 of 40 workers (42.5%) developed acute illness, characterized by high and recurrent fever, headache, myalgia, and complications such as pneumonia, hepatitis, and hematuria. Six patients required hospitalization. Ten years later (2025), 14 patients were re-evaluated. Twelve presented persistent phase I IgG titers, and 10 reported long-term complications compatible with chronic Q fever, including cardiac and respiratory disorders and persistent fatigue. One patient presented a phase I antibody titer of 1024 associated with a history of endocarditis, suggesting persistent infection. Patients with dyspnea and heart disease were monitored to assess the need for treatment.
CONCLUSIONS:
This study documents the first Q fever outbreak in Brazil and demonstrates substantial long-term morbidity among affected workers a decade after exposure. The findings highlight the importance of early diagnosis, appropriate treatment, and long-term surveillance following Q fever outbreaks, particularly in occupational settings with high exposure risk.
Q fever is a neglected zoonosis and is rarely considered in the differential diagnosis of acute febrile illness1. The first Q fever outbreak in Brazil occurred in 2015 among slaughterhouse workers in the São Paulo state. This study aimed to report the outbreak and to retrospectively assess the long-term clinical and serological outcomes of affected workers ten years later.
METHODS:
In 2015, paired serum samples from slaughterhouse workers were tested by indirect immunofluorescence assay (IFA), and Q fever was confirmed by a fourfold rise in Coxiella burnetii antibody titers2. Molecular investigation was performed using polymerase chain reaction (PCR)3. In 2025, workers were re-evaluated through structured questionnaires addressing workplace conditions, clinical manifestations, and long-term complications. Medical records were reviewed, and current serum and whole blood samples were analyzed by IFA and PCR, respectively, to assess the present serological and molecular status.
RESULTS:
During 2015, 17 of 40 workers (42.5%) developed acute illness, characterized by high and recurrent fever, headache, myalgia, and complications such as pneumonia, hepatitis, and hematuria. Six patients required hospitalization. Ten years later (2025), 14 patients were re-evaluated. Twelve presented persistent phase I IgG titers, and 10 reported long-term complications compatible with chronic Q fever, including cardiac and respiratory disorders and persistent fatigue. One patient presented a phase I antibody titer of 1024 associated with a history of endocarditis, suggesting persistent infection. Patients with dyspnea and heart disease were monitored to assess the need for treatment.
CONCLUSIONS:
This study documents the first Q fever outbreak in Brazil and demonstrates substantial long-term morbidity among affected workers a decade after exposure. The findings highlight the importance of early diagnosis, appropriate treatment, and long-term surveillance following Q fever outbreaks, particularly in occupational settings with high exposure risk.
| eISSN: | 2654-1459 |
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