Epidemiological and molecular survey of Coxiella burnetii from the serum of patients suspected of brucellosis in west of Iran.

Q fever is a global bacterial disease that affects both humans and animals. The etiological agent of the disease is Coxiella burnetii. The aim of the investigation was to detect the existence of C. burneti in the serum samples of patients with symptoms of fever and suspicion of brucellosis in the west of Iran. In the current survey, 150 Wright agglutination assay were collected from health centers in Lorestan, Hamadan, Ilam, Kermanshah, and Kurdistan provinces in 2023. DNA was extracted from all these samples, which were taken from individuals suspected of having brucellosis. Then, a nested PCR reaction was applied to diagnose C. burnetii for the transposon gene IS1111. The IS1111 gene replication assays, indicated that 3.3 % (95 % CI: 1.43 %-3.33 %) of the tested serum samples, were positive for C. burnetii. The highest prevalence of C. burnetii infection was found in the Kurdistan province at 6.67 % (95 % CI: 1.85 %-21.33 %). Additionally, a high affinity (ranging from 99 % to 100 %) was recognized among the IS1111 gene sequenced in the present study and those from different area around the world. These results provide strong evidence that individuals with brucellosis in west of Iran may also have C. burnetii co-infection with coxiellosis. Therefore, it is important to consider Q fever as a co-infection in patients suspected of brucellosis.