Recombinant vaccines against leptospirosis.

Leptospirosis is an important neglected infectious disease that occurs in urban environments, as well as in rural regions worldwide. Rodents, the principal reservoir hosts of pathogenic Leptospira spp., and other infected animals shed the bacteria in their urine. During occupational or even recreational activities, humans that come into direct contact with infected animals or with a contaminated environment, particularly water, are at risk of infection. Prevention of urban leptospirosis is largely dependent on sanitation measures that are often difficult to implement, especially in developing countries. Vaccination with inactivated whole-cell preparations (bacterins) has limited efficacy due to the wide antigenic variation of the pathogen. Intensive efforts towards developing improved recombinant vaccines are ongoing. During the last decade, many reports on the evaluation of recombinant vaccines have been published. Partial success has been obtained with some surface-exposed protein antigens. The combination of protective antigens and new adjuvants or delivery systems may result in the much-needed effective vaccine.