Förekomst av Chlamydia/Chlamydophila spp hos gris med och utan konjunktivit.

ABSTRACT Chlamydia and Chlamydophila are species of a family of bacteria (Chlamydiaceae) that cause a range of diseases, including conjunctivitis, in a variety of animals including pigs and humans. Some species cause zoonotic disease. This study examined the occurrence of Chlamydiaceae in samples taken from the lower eyelid conjunctiva in pigs with and without conjunctivitis. The study was initiated based on a herd investigation aimed to examine the experienced increase of conjunctivitis in some finisher herds. This study was conducted as a case-control study, by collecting samples from 62 case pigs (16-26 weeks old) and an equal number of controls, from three herds in Uppland, Sweden. The samples were analysed by real-time PCR (23S rRNA gene of Chlamydiaceae). When employing a threshold value of Ct 36, a significant difference in the occurrence of Chlamydiaceae between the entire case group (83% positive samples) and the control group (65% positive samples) was detected. In one of the herds a significantly higher occurrence of Chlamydiaceae was shown in pigs with conjunctivitis, compared to pigs without conjunctivitis. In the other two herds no significant difference was shown. The study revealed no significant difference in the occurrence of Chlamydiaceae between the herds. When employing av threshold value of Ct 38, the difference between the case and the control group were no longer significant. Hence, a relationship between Chlamydiaceae spp and conjunctivitis in pigs could not be convincingly demonstrated in the present study. However, based on the total results of this study, it is possible that such a relationship exist but with varying expression of clinical signs. The variation in clinical expression could be due to differences in infectious dose, differences in virulence between sub-species of Chlamydia/Chlamydophila, mixed infections of Chlamydia/Chlamydophila or mixed infection with other microorganisms such as Mycoplasma spp or virus. Conjunctivitis caused by Chlamydiaceae could at reinfections be a delayed hyper-sensitivity reaction, be caused by the fact that several species within the Chlamydiaceae exhibit the ability to induce a delayed hyper-sensitivity reaction in the host. The presence of Chlamydiaceae in pigs, their pathogenicity and the pig's immune response to the microorganism is not well studied and these fields require both extended and advanced studies.SAMMANFATTNING Chlamydia spp och Chlamydophila spp är arter i en familj bakterier (Chlamydiaceae) som orsakar en rad sjukdomar, bl a konjunktivit, hos ett stort antal djur inklusive gris och människa. En del av arterna har även zoonotisk potential. Denna studie har undersökt förekomsten av Chlamydiaceae i prover tagna från nedre ögonlockets konjunktiva hos grisar med och utan konjunktivit. Studien initierades efter en besättningsutredning föranledd av en ökad förekomst av konjunktivit i vissa besättningar. Undersökningen har genomförts som en fall-kontrollstudie, genom provtagning av 62 stycken slaktsvin och lika många kontroller i åldern 16-26 veckor, från tre stycken uppländska besättningar. Proverna har analyserats med realtids-PCR av 23S rRNA-genen hos Chlamydiaceae. När Ct <36 användes som tröskelvärde, påvisades en signifikant skillnad i klamydiaförekomst mellan fall (83 % positiva prov) och kontroll (65 % positiva prov) totalt i det undersökta materialet, samt i en av de tre provtagna besättningarna. Hos de övriga två besättningarna sågs ingen signifikant skillnad i klamydiaförekomst mellan fall och kontroller. Det sågs heller ingen signifikant skillnad i klamydiaförekomst mellan besättningarna. När Ct