Q fever: prevalence of antibodies to Coxiella burnetii in the Basque country.

The aim of this study was to ascertain the prevalence of Coxiella burnetii infection in the Basque population. To this end a stratified sampling was carried out taking as a criterion the size of the population in a given area of residence. Residents in sparsely populated areas were found to have a prevalence of 38.5%, significantly greater than in highly populated areas (odds ratio [OR] = 1.56; 95% confidence interval [CI]: 1.08-2.27 and OR = 1.58; 95% CI: 1.09-2.30). The prevalence was significantly higher in males (36.3%) than in females (29%), and was found to increase significantly with age. Current or previous participation in activities relating to agriculture and/or livestock farming or even having contact with cattle, goats or sheep were also found to be risk factors for the infection. A fuller study of the determinants of chronic Q fever should be initiated.