Prevalence of chlamydial infections in breeding sows and their correlationto reproductive failure.

To investigate the prevalence of chlamydial infection and their significanc e for reproductive disorders in sow breeding herds in Germany, blood sample s of 1493 pigs were taken for a serological survey by enzyme-linked-immunos orbent-assay (ELISA). Antibodies to Chlamydiae were found in 33 % of the sa mples, in all herds investigated responders could be detected. The rate of seropositive animals in different farms varied from 4,3 % to 72,7 %. The pe rcentage of positive responders in the farms correlated positively with the occurrence of MMA-syndrome (mastitis, metritis, agalactia), return to oest rus and diseases of the piglets. Also these herds showed less weaned piglet s per sow and litter. Comparison of seronegative and seropositive sows with in single farms revealed also worse reproductive data for seropositive sows . A significant relationship could be found between farms with a high quota of seropositive sows and poor hygiene status as well as poultry keeping. As a second step 124 cervical swabs and 9 aborted piglets were investigated for chlamydial antigen by capture-ELISA and polymerase chain reaction (PCR ). Using the capture-ELISA for investigation only 3 probes with chlamydial antigen could be detected, however, examination by the more sensible PCR ga ve positive results in 50 % of the probes. 20 % of the PCR-positive animals were clinically healthy sows, 80 % of the PCR-positive probes originated f rom sows with reproductive disorders. A significant relationship could be s hown between PCR-positive probes and the incidence of abortion and litters with stillborn piglets and piglets with low viability. Swabs from 93 of the 124 sows were investigated as well for other bacterial pathogens of reprod uctive disorders. A high degree of micro-organisms of different species cou ld be detected in 70 % of the samples of sows with reproductive disorders a nd in 35 % of the samples of clinically healthy sows. Species differentiation of the chlamydial antigen positive samples was done by southern blot hybridisation. Herewith C, psittaci could be diagnosed in all positive samples. Additionally 8 probes revealed a mixed infection wit h C. psittaci and C. trachomatis. The results of the present study show, th at the prevalence of chlamydial infections in breeding herds is high and un derline the importance of chlamydiaI infections for reproductive disorders. Single chlamydiaI infections as well as mixed infections with other pathog ens must be considered.