Molecular Evidence for Subclinical Infection of Chlamydia pecorum in Captive Koalas (Phascolarctos Cinereus) of Japanese Zoos

<jats:p>Chlamydial infections pose a significant threat to the health and long-term survival of koalas. However, the pathogenesis of this disease is not well understood. Chlamydia pecorum (C. pecorum) is an important pathogen affecting wild koalas’ health and their survival. However, the infection status of C. pecorum remains largely unknown in captive koalas across Japanese zoos. Therefore, in this study, we aimed to determine the infection status of C. pecorum in koalas from seven Japanese zoos. We tested swab samples obtained from koalas of these zoos for C. pecorum using qPCR and conventional PCR. We found a 21.74% overall prevalence of C. pecorum in these koalas. Female koalas showed a higher prevalence (24.24%) than male koalas (15.38%). However, no direct association was observed between koala health and C. pecorum loads. Notably, among C. pecorum positive koalas, some showed higher chlamydial loads without any classic signs associated with the progression of chlamydial diseases, such as ocular inflammation and wet bottom. We found higher C. pecorum load in adult koala than other groups. These results shed light on the subclinical infection of C. pecorum in captive koalas, and also may act as a guide for future control measures.</jats:p>