Leptospiral carriage by mice and mongooses on the island of Barbados.

Leptospirosis is a zoonotic disease, maintained by chronic infection of the kidneys of reservoir animals, usually small mammals. Infection in humans is acquired from direct or indirect exposure to the urine of infected animals. Leptospirosis has a high incidence in tropical regions, and has been studied extensively in several Caribbean countries. We studied the carriage of Leptospira serovars by two small mammals which are potential maintenance hosts of the disease in Barbados. A total of 136 mongooses (Herpestes auropunctatus) and 97 mice (Mus musculus) were caught in live traps. Leptospiral antibodies were detected by microscopic agglutination test (MAT) using antigens representing 12 serogroups, and kidney tissues were inoculated into polysorbate medium for isolation of leptospires. The seroprevalence (at a titre of > or = 100) in mice was 28.2% (24/85, 95% CI 19.0, 39.1) and in mongooses 40.7% (48/118, 95% CI 31.7, 50.1). In mice, antibodies were detected predominantly against serogroups Ballum and Autumnalis, while in mongooses the predominant serogroup was Autumnalis. Leptospires were isolated from 28 mice (28.9%, 95% CI 20.1, 39.0) and from 4 mongooses (2.9%, 95% CI 0.8, 7.4). Mouse isolates were identified as serovars arborea (17) and bim (7). As in other parts of the world, common house mice (Mus musculus) represent a significant reservoir of leptospirosis. Although carriage of the Ballum serovar, arborea, was not unexpected, this represents the first time that an animal reservoir of serovar bim has been identified. This is significant because bim causes about 63% of human leptospirosis in Barbados, and control efforts and education for prevention can now be targeted at a specific reservoir.