Occupationally Acquired Q Fever in Shepherds and Sheep Milk Cheesemakers

Q fever is a zoonosis caused by Coxiella burnetii, and transmission to humans is often associated with contact with ovine and caprine livestock. Those exposed to sheep are particularly at high risk of infection. Recent studies show that Q fever is increasing in sheep farms in Portugal raising alerts on spillover to humans. We detected anti-C. burnetii IgG in shepherds and sheep milk cheesemakers (27 [28.1%] in a total of 96; 95% confidence interval [CI] 19.4-38.2%) and in controls (21 [8.1%] in a total of 260; 95% CI 5.1-12.1%), pointing to an increased risk of C. burnetii infection (P = 0.0001), with an odds ratio for anti-C. burnetii of 4.45 (95% CI 2.4-8.4%; P = 0.0001), in individuals with occupational contact with sheep in Portugal.