burnetii are especially high in goats (up to 70–90%) ( 4, 11) but lower in sheep (usually below 6%) ( 12). burnetii through birth products, vaginal fluids, feces, milk, and urine for several weeks after abortion or normal parturition ( 4– 10), but the bacterial load shed by aborted animals is higher than that shed by those that deliver normally ( 9). burnetii enters into a flock, infection spreads rapidly. Q fever causes abortions in small ruminants ( 3), and once C. burnetii, and both have a significant role as source of human infection ( 1, 2). Goats and sheep are considered the main reservoir of C. Q fever is a widespread zoonosis caused by the intracellular bacterium Coxiella burnetii. The results showed that infection can remain active for over 5 years if effective control and biosafety measures are not correctly implemented. Coxiella burnetii viability in dust measured by culture in Vero cells was demonstrated in two of the flocks, even during the fourth lambing season.

Three genotypes were identified: SNP8 (three flocks, 52.9% of the samples), SNP1 (two flocks, 44.8% samples), and SNP5 (one flock, two environmental samples). burnetii fecal shedding and the bacterial burden detected in dust, whereas shedding by vaginal route affected the detection of C. A significant relationship was found between C. burnetii shedding in the flocks, with a general progressive decrease in bacterial shedding throughout the years, interrupted in three flocks by peaks of reinfection associated with specific management practices. Real-time PCR analyses showed different trends in C. BTM samples and aerosols (outdoors and indoors) were monthly collected between lambing and the end of milking. During four consecutive lambing seasons (2015/16–2018/19), samples were collected within 1 week after each lambing period from animals (vaginal swabs, milk and feces from ewes, and yearlings) and the environment (dust indoor sheep premises). burnetii DNA in bulk-tank milk (BTM) and a high seroprevalence in yearlings during the previous milking period (Spring 2015).

Flocks with an active infection were selected based on the presence of C.

Progression of Coxiella burnetii infection in four naturally infected sheep flocks, and in their farm environment, was monitored throughout four lambing seasons.

3Department of Animal Pathology, Veterinary Faculty, University of Santiago de Compostela, Lugo, Spain.

2Laboratory of Special Pathogens, Instituto de Salud Carlos III, Centro Nacional de Microbiología, Madrid, Spain.

1Animal Health Department, NEIKER-Instituto Vasco de Investigación y Desarrollo Agrario, Derio, Spain.

Barandika 1, Isabel Jado 2, Ana Hurtado 1, Ceferino M.

Four flocks