Serosurvey of Coxiella burnetii in high risk population in Turkey, endemic to Crimean-Congo haemorrhagic fever virus.

Background & objectives: Q fever caused by Coxiella burnetii is a zoonotic infection that spreads to human beings from animals. This study was aimed to demographically examine the C. burnetii seroprevalence in the people living in villages where Crimean-Congo haemorrhagic fever virus (CCHFV) is endemic, in terms of various risk factors such as tick bites, tick contact, and occupational groups.

Methods: A total of 440 serum samples from those living in rural areas of Sivas and Tokat regions in Turkey were included in the study as a risk group; 387of them were serologically CCHFV positive (as confirmed in our previous research). Serums of the control group composed of 110 people living in urban areas. In all serum samples, IgG antibodies of C. burnetii against phase-I and phase-II antigens were diagnosed using the ELISA method.

Results: Coxiella burnetii seropositivity was detected in 19.09% of those living in rural areas and 4.55% of those living in urban areas (p < 0.001, OR = 4.96). In terms of their approach to the ticks, no statistical difference was observed between the risk groups in the chi-square test (p = 0.787). However, according to univariate analysis, the absorbance means of antibodies reactive to C. burnetii was statistically higher for the rural people who have made contact with ticks than those who have not (p = 0.017). No seroepidemiological relation was found between CCHFV and C. burnetii serology (p = 0.787), and the rate of co-seropositivity between them was 5.43% (21/387).

Interpretation & conclusion: The findings of the study showed that C. burnetii infection is epidemic especially in the people living in rural areas. Contact with ticks in various ways might have resulted in the increased risk of C. burnetii infection in the study. Personal protective measures against tick bites may be important for reducing Q fever risk as in other tick-borne infectious disease.