Prevalence and risk factors of ovine enzootic abortion caused by Chlamydia abortus in the Layyah district of Punjab, Pakistan

Chlamydia abortus causes enzootic abortion in sheep and poses a zoonotic public health threat. Since chlamydiosis leads to significant economic losses, this cross-sectional sero-epidemiological study was conducted to determine the prevalence of antibodies against Chlamydia abortus in ewe flocks with a history of abortion from the district Layyah of Pakistani Punjab. For this purpose, 184 serum samples were tested from 50 privately owned sheep flocks located across three sub districts (Tehsils) by commercially available iELISA kit. The seroprevalence (%) along with 95% confidence intervals (CI) were calculated, and potential risk factors were analysed. A 25.8% (CI 15.2-39.6) flock-based and 7.9% (CI 4.4-12.6) individual-based true seroprevalence was observed. The highest seroprevalence was recorded in Tehsil Layyah (58.7% flock-level and 18.5% individual-level) followed by Karor Lal Esan (17.4% flock-level and 4.7% individual-level), whereas no flock was found positive in Tehsil Choubara. The association of potential risk factors; age group, flock size, feeding system, rearing system, species and breeds, with seropositivity was determined by chi-square testing. Only the history of abortions was found to be significantly (OR: 11.0, p < 0.001) associated with the higher seroprevalence in the sampled flocks. This study is the first to document the seroprevalence of ovine enzootic abortion from the district of Layyah, and we recommend further investigations and extension efforts to consider a control strategy in affected flocks.