Q fever episodes on three dairy goat operations (A–C) were followed after animals received an inactivated Coxiella burnetii phase I vaccination. Prior to immunization, two phase-specific ELISAs were used on serum samples to determine the existing infection status. Shedding dynamics were assessed through vaginal swabs collected across three consecutive kidding seasons and through monthly bulk tank milk (BTM) testing. In addition, monthly dust swabs were taken from a single windowsill in each barn as well as from the milking areas to evaluate indoor contamination; all samples were examined via qPCR. Phase-oriented serology indicated that herd A was undergoing an acute infection, whereas herds B and C showed, respectively, an active and a historical infection pattern. Vaginal excretion occurred in all three herds during every monitored kidding season. Altogether, C. burnetii DNA was detected in 50%, 69%, and 15% of BTM samples from herds A, B, and C. Dust from barns contained pathogen DNA in 71%, 45%, and 50% of the corresponding swabs. The highest proportion of positive samples originated from milking parlors (A: 91%, B: 72%, C: 73%), underscoring a substantial exposure risk for humans during the milking process.
