Rodents and Leptospira transmission risk in Terceira island (Azores)

The role of rodents as Leptospira renal carriers in Terceira island was eva luated (1993-1995) through kidney culture and serology [microscopic aglutin ation test (MAT)] of 94 mice and rats. Fifty-nine animals were positive (n = 41 by serology + culturing; n = 11 serology; n = 7 culturing), presenting a wide distribution in man-made and natural areas. House mice had the high est bacteriological (82.9%) and serological (90.9%) rates, being strictly r elated to serovar arborea. Black rats were involved in the dispersion of al l isolated L. interrogans sensu lato serovars (arborea, copenhageni and ict erohaemorrhagiae). Logistic regression analysis and non-metric multi-dimens ional scaling, relating Leptospira infection with biological and environmen tal variables, expressed that adult males Mus domesticus, sexually active a nd living in humid biotopes, mainly above 500 m, are the most likely reserv oirs. This study emphasizes the role of house-mice in the epidemiology of l eptospirosis in Terceira and the need of reducing the risk of Leptospira tr ansmission through integrated control programmes, primarily focusing on adu lt house-mice in peri-domestic environments, before the breeding season.