Emerging evidence for Q fever in humans in Denmark: role of contact with dairy cattle.

Until recently, Q fever was notified in very low numbers annually in Denmark and it was always considered to be acquired abroad. Preliminary reports now describe Coxiella burnetii in milk samples from Danish dairy cattle. Serum samples of a large cohort of farmers, veterinarians, inseminators and hoof trimmers, all having occupational contact with dairy cattle, were tested for the presence of IgG to phase I and phase II antigens of C. burnetii. In 39 of 359 individuals studied (11%), the presence of antibodies to C. burnetii was found. Veterinarians had the highest seropositivity rate (36%). This survey suggests that C. burnetii is a recently recognized domestic infection in Denmark and that risk of infection is associated with occupation.