Seroprevalence of Coxiella burnetii, the causal agent of Q fever in humans, was examined in wild brown rat populations from 4 Oxfordshire farmsteads (n = 127), 9 Somerset homesteads (n = 98), and 1 captive enclosure (n = 88) in the UK. Seroprevalence ranged between 7 and 53%, the lowest being within the captive population and the highest on dairy farmsteads with sheep present. This is the first reported investigation of C. burnetii in wild rats outside India. We suggest that the high Seroprevalence among rats (i) provides evidence that wild rats constitute an important reservoir for C. burnetii in the UK, and (ii) explains why cats, as frequent predators of rats, are so important in the epidemiology of this disease.
