Prevalence Study of Coxiella burnetii in Aborted Ovine and Caprine Fetuses by Evaluation of Nested and Real-Time PCR Assays

Problem statement: Q fever is a ubiquitous zoonosis caused by Coxiella burnetii, an obligate intracellular rickettsial organism that caused abortion and stillbirth in ruminants. Approach: The prevalence of Coxiella burnetii in Iran is essentially unknown. Its traditional diagnosis is based on culture, serology and conventional PCR. In this present study, for more sensitive and accurate detection and prevalence's determination of Coxiella burnetii in aborted Ovine and Caprine fetuses, the nested and real-time PCR methods are recommended. Results: About 98 (12.53%) and 122 (16.39%) out of 782 and 744 Ovine and Caprine aborted fetuses, were positive for presence of Coxiella burnetii by nested PCR, respectively. After LSI Taqvet Coxiella burnetii real-time PCR, it was recognized that 121 (15.47%) and 152 (20.43%) samples were positive for Coxiella burnetii in Ovine and Caprine aborted fetuses, respectively. Results indicated that the real-time PCR was 7 times more sensitive than the nested PCR. Statistical analysis showed significant differences about P<0.01 between presence of Coxiella burnetii in aborted Ovine and Caprine fetuses by both nested and real-time PCR assays and P<0.05 between ability of nested and real-time PCR for detection of Coxiella burnetii. The Ct values which obtained from real-time PCR had significant differences about P<0.01 for presence of Coxiella burnetii between aborted Ovine and Caprine fetuses. Our results indicated that Caprine is more sensitive than Ovine to Coxiella burnetii’s abortion Khozestan and Gilan have the highest and Khorasan and Sistan va Baluchistan provinces have the lowest prevalence of Coxiella burnetii, respectively. Conclusion: To our knowledge, this study is the first prevalence report of direct identification of Coxiella burnetii in aborted Ovine and Caprine fetuses by evaluation of nested and real-time PCR assays in Iran. This study showed that the nested PCR for detecting Coxiella burnetii are technically time-consuming and labor-intensive.