02212nas a2200289   4500000000100000000000100001008004100002260007000043653001200113653001000125653000800135653001900143653002300162653002500185100001300210700001400223700001400237700001300251700001200264700001400276245017300290250000900463300001200472490000800484520141600492022001401908       2017                            d  c09/2017bSchlütersche Verlagsgesellschaft mbH & Co. KGaHannover10aQ fever10aELISA10aPCR10aseroconversion10aseronegativization10acolostral antibodies1 aM Freick1 aA Konrath1 aH Enbergs1 aR Diller1 aJ Weber1 aJ Walraph00aCoxiella burnetii: Decline of antibody response in pluriparous dairy cows during dry period and maternal antibody levels in dairy calves in an endemically infected herd  a9/10  a388-3940 v1303 aCoxiella burnetii (C. burnetii), an intracellular zoonotic bacterium causing Q fever, is widely distributed in cattle herds. In this study, we investigated changes in antibody response during dry period in dairy cows and the course of maternal antibody levels in dairy calves by using a commercial ELISA. In a total of 35 pluriparous cows, the proportion of seropositive animals (65.7% vs. 42.9%) (p = 0.039) and the mean antibody score levels (2.8 ± 2.4 vs. 1.0 ± 1.4) (p  lt; 0.001) declined significantly from dry cow therapy to calving. During this period, 2/12 (16.7%) formerly seronegative cows seroconverted, whereas in 10/23 (43.5%) of the seropositive animals a seronegativization occurred. C. burnetii DNA was detected by PCR in 15/35 (42.8%) of the vaginal swabs obtained immediately after calving. All twelve calves enclosed in this study were born seronegative and precolostral whole blood samples of the calves were tested negative by PCR for C. burnetii DNA. After colostrum intake, 7/12 (58.3%) of these calves seroconverted and stayed seropositive until day 33. Afterwards, the proportion of seropositive calves and the antibody scores decreased gradually. From day 103 after birth on, all calves remained seronegative. In conclusion, we recommend the exclusion of cows for the period of colostrogenesis and calves after colostrum intake from seroepidemiological investigations to avoid bias.  a0005-9366