A serological survey was conducted to determine the seroprevalence and risk factors of leptospirosis in commercial dairy cattle in Chittagong, Bangladesh during the period of April 2011 to September 2012. This study was carried out by randomly selected six farms having 206 dairy cows. A total of 110 serum samples were collected for the detection of Leptospira (L.) interrogans serovar Hardjo antibody by ELISA. The results showed that a total of 52 sera were positive (seroprevalence 47.27%). Urine samples were collected from seropositive animal for the detection of Leptospira organisms under dark field microscopy but none were found positive. The univariate analysis revealed that the prevalence of leptospirosis was significantly higher in lactating animals and pregnant cows (P<0.05). Among farm level exposures; owner’s educational qualification, source of semen, size of farm, farm and number of employees were potential factors of leptospirosis (P<0.05). A multivariate analysis showed that the higher educational qualification of farm owners (OR=1.35), farms having more than 15 employee (OR=13) and farms located in peri-urban areas (OR=1.14) had higher risk of leptospirosis. However, the study concluded that leptospirosis is prevalent and distributed among dairy farms in Chittagong, Bangladesh. The seropositive dairy cows did not show any evidence of disease except abortion, stillbirth and death of weak calves. Further studies need to be carried out to prove the infectivity, serovar determination and implementation of preventive measures among dairy farm and people at risk.

Key words: Bangladesh, Cattle, Chittagong, Leptospirosis, Prevalence, Risk factors