Epidemic of Q fever in Leszno district in Poland.

In 1988 an epidemic of Q fever was detected in Leszno district. During 1973-1985 all 28,066 cattle tested for C. burnetii antibodies were found to be negative. The first seroconversions were found in cows which produced stillborn young. In the following years the number of seropositive cattle increased from 8.4% in 1987 to 21.6% in 1989. In 1988 all animal workers in the district were tested for C. burnetii antibodies. Of 4,264 persons tested, 1,451 (34%) were seropositive. A detailed study of workers and animals on one farm were performed. A herd of animals was found to be seropositive (32.1%), 68% of workers in direct contact with infected animals were seropositive and 29% of persons drinking raw milk. C. burnetii strains have been isolated from ticks, wild animals and birds hunted in close proximity of the farm. The dynamics of C. burnetii infection among animals and humans in this district and the fact that there is no importation of animal herds suggests that the possible route of introduction of Q fever in this area may be with imported semen or breeding bulls. The presence of C. burnetii in ticks and wild animals indicates the transfer of Q fever to the natural environment and its maintenance in this territory.