Emerging Q Fever Infection in Türkiye

Q fever, caused by Coxiella burnetii, is an underrecognized zoonotic infection with diverse clinical manifestations. The nonspecific nature and slow progression of Q fever frequently delay diagnosis, sometimes leading to severe or even fatal outcomes. This study describes 32 patients diagnosed with Q fever over an 18-month period in a previously unreported region, highlighting the emerging awareness of this neglected zoonosis.

Patients with seropositive C. burnetii Phase I/II IgM and/or IgG antibodies between October 2023 and March 2025 (18-month period) were included. Cases were classified as acute, probable, chronic, or past infection according to established serological and clinical criteria.

Thirty-two patients were diagnosed during the study period, of whom 22 (68.8%) were male; the median age was 60.5 years (IQR: 48-66). More than half were farmers, and 40.6% reported animal exposure. Based on serological and clinical criteria, 11 patients were diagnosed with acute Q fever, 16 with probable infection, one with chronic infection, and four with past infection. Common manifestations included fever, myalgia, arthralgia, hepatitis, and endocarditis; cardiovascular involvement occurred in 40.6% of patients. Two patients died, and notably, three patients with prosthetic valve endocarditis had a history of care at the same cardiac surgery clinic.

Given its heterogeneous clinical manifestations and variable serological responses, Q fever poses significant diagnostic challenges. This study presents the first and largest human case series of Q fever from the Black Sea region of Türkiye, highlighting the wide clinical spectrum of the disease and the need for enhanced awareness and diagnostic capacity.