PREVALENCE OF LEPTOSPIRA SPP IN WILD BROWN-RATS (RATTUS-NORVEGICUS) ON UK FARMS

Wild brown rats (Rattus norvegicus) are frequently implicated in the c arriage and spread of Leptospira spp. Wild brown rats (n = 259) were t rapped from 11 UK farms and tested for Leptospira spp. using a number of diagnostic tests. The prevalence of leptospiral infection was low, but there was variation in the results obtained with the different dia gnostic tests. Estimates of prevalence ranged between 0% by silver-sta ining of tissues, 1% by the microscopic agglutination test, 4% by the enzyme-linked immunosorbent assay, 4% by culture, and 8% by fluorescen t antibody technique. In total, 37 (14%) rats were positive by at leas t one of the tests, which contrasts with the frequently reported preva lences of 50-70% for wild rats in the UK. Serovar bratislava was as pr evalent as icterohaemorrhagiae, although it was present only on farms with larger rat populations.