Development of a simple serological method for diagnosing leptospirosis: a microcapsule agglutination test.

A passive microcapsule agglutination test for the diagnosis of leptospirosis was developed by utilizing chemically stable microcapsules instead of sheep erythrocytes. In the test, sonically disrupted antigens of leptospira were sensitized to microcapsules treated with glutaraldehyde. Compared with the microscopic agglutination test, the passive microcapsule agglutination test showed a relatively genus-specific tendency and a 4- to 32-fold-higher sensitivity. The sensitized microcapsule antigens were stable for at least 1 year. The microcapsules coupled with mixed antigens can be used as a serodiagnostic screening test for diseases caused by various types of leptospira. The test, which is very simple and reproducible and requiring no specific training, can be employed easily as a routine test in diagnostic laboratories.