Leptospira Epidemiology in Dairy Cattle of Bangladesh

Bovine Leptospirosis causes enormous economic loss due to reproduction failure and production loss.It has been perceived as a rising global public health concern.Bovine species acts as career or vectors, whereas human are the dead end host.No scientific attempt has previously been taken to investigate epidemiological diversity of Leptospira in commercial dairy cattle in Bangladesh.Hence, a cross -sectional study was conducted in commercial dairy cattle in Bangladesh to describe epidemiological scenario of Leptospira.Nineteen upazillas or sub -districts from 12 districts of 7 divisions were randomly chosen for the study.A total 43 dairy cattle farm, 1-6 farms per upazilla was recruited based on the presence of increasing abortion history within past six months.A pretested questionnaire was used to collect epidemiological information through face-to-face interview and direct observation.Blood and urine samples and aborted fetuses were collected for laboratory evaluation.Sero-positivity for Leptospira hardjo was evaluated on the samples obtained using OIE protocol-based Enzyme Linked Immuno Sorbent Aaasay (ELISA) technique.Dark Field Microscopy (DFM) Examination was carried on urine samples.Aborted fetus was evaluated through bacteriological culturing followed by Polymerase Chain Reaction (PCR).The PCR positive samples were further sequenced for phylogenetic analysis.The overall seroprevalence of Leptospira was 17.9% (95% CI: 9.4%-31.4%) in dairy cattle in Bangladesh.The proportionate Leptospira prevalence was 55.6% in cattle (n = 45 urine samples) and 32% in fetuses (n = 25) and 32% in specimens obtained from fetuses (n = 100) were estimated from urine and fetal sample, respectively.Breed (Exotic vs Cross: OR = 3.4) and age (≤ 4.5 vs ≥ 4.6: OR = 5.0) were identified as potential risk factors for Leptospira sero-prevalence in dairy cattle.One of the sequences of Leptospira isolate in the present study had a close congener (78%) of the sequence of Leptospira isolated from cattle in Brazil.Overall results suggest Leptospira is commonly circulating in dairy cattle in Bangladesh.Preventive measures including breed selection, vaccination status, quarantine of new animals, and exclusion of wildlife vectors, and farm superintendence should be practiced.Field veterinarians should also be properly educated in handling abortion cases and treating animals for prophylactic measures..