Molecular investigation of Coxiella burnetii and Francisella tularensis infection in ticks in northern, western, and northwestern Iran

Tularemia and Q fever are endemic diseases in Iran; however, little information is available on the prevalence of the causative agents, Coxiella burnetii and Francisella tularensis, in Iranian ticks. This study investigated C. burnetii and F. tularensis among hard ticks in this country. We collected ticks from livestock and other mammals in Guilan, Mazandaran, Golestan (northern Iran), Kurdistan (western Iran), and West Azerbaijan (northwestern Iran) provinces. Genomic DNA from collected ticks was extracted and screened for C. burnetii and F. tularensis using Real-time PCR. A total of 4,197 ticks (belonging to 12 different species) were collected, and Ixodes ricinus (46.4%), Rhipicephalus turanicus (25%), and Rhipicephalus sanguineus sensu lato (19.1%) were the most collected species. Of 708 pooled tick samples, 11.3% and 7.20% were positive for C. burnetii and F. tularensis, respectively. The genus of Rhipicephalus had the highest (18.3%) C. burnetii infection among the collected tick pools (P<0.001). Furthermore, the most positive pools for F. tularensis belonged to Haemaphysalis spp. (44.4%). Kurdistan had the most significant percentage of C. burnetii-infected ticks (92.5%), and there was a meaningful relationship between the provinces and the infection (P< 0.001). The ticks from Golestan exhibited the highest F. tularensis infection rate (10. 9%), and the infection showed no significant relationship with the provinces (P = 0.19). Ticks collected from grasslands had a higher Coxiella burnetii infection rate than those collected from animals (39.4% vs. 7.9%; p<0.01). However, ticks collected from animal surfaces had a slightly higher rate of Francisella tularensis infection than those collected from grasslands (7.6% vs. 3.9%; p = 0.24). Here, we demonstrated the presence of both pathogens in the north (Guilan, Mazandaran, and Golestan provinces), the west (Kurdistan province), and the northwest (West Azerbaijan province) of Iran. The public health system should pay particular attention to tick bites in veterinary medicine and humans.