Chlamydia: Chlamydia psittaci, Chlamydia pneumoniae, and Chlamydia trachomatis. C. psittaci is a lethal intracellular bacterial species that causes avian chlamydiosis, epizootic outbreaks in mammals and respiratory psittacosis in humans

Chlamydial organisms are members of an exclusive order, Chlamydiales and family Chlamydiaceae. Chlamydia psittaci is a bacterium that causes psittacosis in humans and ornithosis, pneumonitis, abortion, encephalomyelitis, and enteritis in various animals. The purpose of this study was to determination of abortion rate caused by C. psittaci in Iranian cattle using PCR method. DNA was extracted from 145 aborted bovine fetus samples of cattle. Then, ompA region of C. psittaci genome was amplified by PCR using specific primers. The primers pair CTU and CTL used for amplification of a 1058 bp fragment of the C. psittaci ompA gene. Association between Chlamydia infection and abortion in cattle were examined by T test statistical analysis. P values <0.05 were considered significant. C. psittaci was found in 14 out of 145 samples (9.65%). Amplified fragments for ompA region on 1% agarose gel revealed a fragment of about 1058 bp. The results showed that the C. psittaci is one of the major causes of infectious abortion in cattle. C. psittaci has been screening from outbreaks of epizootic cattle abortion at different stages of pregnancy. Abortion occurred mostly in middle or late pregnancy. C. psittaci is associated with significant morbidity and mortality during pregnancy, and its rarity can delay early diagnosis and treatment. Isolation of C. psittaci from aborted bovine fetus specimens indicated a wide dissemination of this pathogen among cows in Iran. The control of this microorganism is useful for prevention and reduction of the incidence of abortion and reduce the economic loses in Iran. Keywords— Chlamydia psittaci, abortion, PCR, Iranian cattle.