Seroepidemiological study of Q fever in domestic ruminants in semi-extensive grazing systems

ELISA anti-C. burnetii antibody prevalence was slightly higher in sheep (11.8 ± 2.0%) than in goats (8.7 ± 5.9%) and beef cattle (6.7 ± 2.0%). Herd prevalence was 74% for ovine, 45% for goat and 43% for bovine. Twenty-one percent of sheep flocks, 27% of goat and 14% of cattle herds had a C. burnetii seroprevalence ≥ 20%. Only 15 out of 214 ELISA-positive animals reacted positive by CFT. Age-associated seroprevalence differed between ruminant species with a general increasing pattern with age. No evidence of correlation between abortion history and seroprevalence rates was observed despite the known abortifacient nature of C. burnetii in domestic ruminants.Results reported herein showed that sheep had the highest contact rate with C. burnetii in the region but also that cattle and goats should not be neglected as part of the domestic cycle of C. burnetii. This work reports basic epidemiologic patterns of C. burnetii in semi-extensive grazed domestic ruminants which, together with the relevant role of C. burnetii as a zoonotic and abortifacient agent, makes these results to concern both Public and Animal Health Authorities.Q fever is a worldwide distributed zoonosis caused by Coxiella burnetii, a ubiquitous Gram-negative bacterium that is able to infect humans and a wide range of animals, both aquatic and terrestrial [1-3]. Q fever is a polymorphic disease in humans with subclinic, acute and chronic forms [1,3]. Several groups in Spain have studied the clinical aspects and the distribution of the disease in different regions [5-7]. The disease seems to be more prevalent in northern Spain than in the central and southern regions of the country, and it is especially high in the Basque Country (northern Spain) where large series of human pneumonia cases due to C. burnetii have been reported [1,8]. It is proposed that C. burnetii is maintained in nature following two different cycles, the wild cycle in which ticks and wild animals are involved, and the domestic cycle, whe