LEPTOSPIROSIS IN RUMINANTS: AN UPDATED REVIEW ON EPIDEMIOLOGY, PATHOGENESIS, DIAGNOSIS AND ONE HEALTH CONTROL STRATEGIES

Leptospirosis is a globally distributed bacterial zoonosis caused by pathogenic spirochaetes of the genus Leptospira, and ruminants are among its most economically important hosts. In cattle, buffaloes, sheep and goats, the disease ranges from acute haemolytic illness in young stock to a chronic, largely subclinical reproductive syndrome marked by abortion, stillbirth, weak neonates, infertility and milk drop. Host-adapted serovars, particularly L. borgpetersenii and L. interrogans serovar Hardjo in cattle, persist in the kidneys and genital tract and are shed in urine and uterine discharges for months, which sustains herd infection and creates continuous occupational exposure for farmers, milkers, veterinarians and abattoir workers. Incidental serovars such as Pomona, Icterohaemorrhagiae, Grippotyphosa and Canicola, acquired from rodents, pigs, dogs and wildlife, cause more severe acute disease. Tropical climate, monsoon flooding, waterlogged paddy fields, communal grazing, mixed species husbandry and rodent infestation make leptospirosis endemic in India, where serosurveys repeatedly record substantial seropositivity in bovines and small ruminants with reproductive disorders. The microscopic agglutination test remains the reference serological test, while real-time PCR targeting lipL32, isothermal assays such as LAMP, and culture provide direct evidence of infection and carrier status. Control rests on detection and treatment of carriers with streptomycin or long-acting oxytetracycline, vaccination with locally relevant serovars, rodent and water management, biosecurity and worker protection. Because the same environmental and animal reservoirs drive human infection, leptospirosis in ruminants is best addressed through an integrated One Health framework linking veterinary, medical and environmental surveillance. This review summarises current knowledge on the aetiology, epidemiology, pathogenesis, clinical and pathological features, diagnosis, treatment, prevention and public health significance of leptospirosis in ruminants, with emphasis on the Indian context, and identifies priority research gaps.