Serodiagnosis and molecular survey on leptospiral abortions in the dairy cattle of Tabriz

Leptospirosis is an important infectious disease of animals and humans caused by the pathogenic leptospires which are classified into one species of Leptospira interrogans containing over 212 serovars. This study was conducted to determine the prevalence of Leptospira-induced abortions in Tabriz (north-west of Iran) dairy herds and to determine the pathogenic Leptospira serovars responsible. From May 2008 through August 2010, 16 (21.05%) of 76 submissions (fetuses and placentas) to the Large Animal Clinic of the Veterinary Faculty at the University of Tabriz were diagnosed as positive to L. interrogans serovars by PCR. In contrast, only 9 (11.85%) of 76 dam’s sera were diagnosed as positive to leptospirosis by the microscopic agglutination test (MAT). Two out of 9 animals were seropositive to serovar pomona, one animal to serovar icterohaemorrhagiae, two animals to canicula, three animals to both pomona and grippotyphosa, and one animal to the both canicula and grippotyphos. Moreover, the prevalence of Leptospira induced abortions was high in the aged cows and advanced pregnancies (7-9 months). However statistical difference was not observed among these groups or different periods of pregnancy. In conclusion, serovar pomona induced abortions were determined to be more common leptospiral abortions in cattle in Tabriz and combination of PCR protocol with the MAT test would be more effective than the single test for etiological diagnosis of bovine abortions.