An ELISA kit to detect antibodies against phase I and IIantigens from the Nine Mile strain of C. burnetii (IDEXX Q Fever, Bern, Switzerland) was used to perform the sero-logical analysis. Serum samples were diluted 1:400, andthe ELISA was performed according to the manufacturer’sinstructions. The OD (optical density) values were readat 450 nm (wave length). Positive and negative controlswere used to validate each test. The test was validated ifthe OD was lower than 2000 for the positive control (PC),higher than 0.5 for the negative control (NC) and the dif-ference between positive control OD and negative controlOD greater than 0.3.