This review evaluates the threat to human health--with the shedding of C. burnetii in dairy animals with reproductive disorders or those without clinical signs. The review also discusses the diagnosis of Q fever in livestock and the possibility of Coxiella-free herds, and it reports the available methods for controlling Q fever. C. burnetii shedding seems to occur frequently in milk taken from asymptomatic dairy cows. The number of Coxiella shed in milk is generally low. The phase I vaccine prevented abortion and greatly decreased the shedding of C. burnetii in milk.