Assessment of Brucellosis Seropositivity in Patients Diagnosed with Tularemia

Tularemia and brucellosis share similar clinical manifestations and pathological characteristics. This study aimed to evaluate the demographic, clinical, and laboratory findings of patients diagnosed during a tularemia outbreak in whom brucellosis co-infection was suspected, to highlight the potential coexistence of these two zoonotic infections and contribute to effective disease management.

Following the tularemia outbreak in Sivas Province during the first half of 2024, the electronic medical records of Sivas Numune Hospital and Sivas Cumhuriyet University Hospital were retrospectively reviewed. Tularemia diagnosis was confirmed in patients presenting with compatible clinical features and a microagglutination test (MAT) titer of ≥1:160. Serum samples that were seropositive for tularemia were further analyzed for Brucella antibodies using the serum agglutination test (SAT). Titers of ≥1:160 in patients without a prior history of brucellosis were considered positive.

Among 162 tularemia patients tested for Brucella, Rose Bengal and Wright agglutination tests were positive in 17 (10.4%) and nine (5.5%) patients, respectively. Five were female and four were male. Five patients resided in rural areas, and six reported involvement in livestock farming or agriculture. Fever was present in six of nine patients, while sore throat and fatigue were reported in all. Tonsillopharyngitis was detected in six patients, and lymphadenopathy was observed in all nine. The duration of symptoms at presentation ranged from 7 to 60 days, and seven patients had received antibiotic treatment before diagnosis.

This study is the first to evaluate tularemia cases with concomitant Brucella seropositivity. The findings suggest that, in brucellosis-endemic regions, Brucella serology should be routinely performed in patients with suspected tularemia to ensure accurate diagnosis and appropriate management.