Leptospirosis, a disease that is often under- or misdiagnosed, significantly impacts human health in many parts of the world and generally affects the most vulnerable communities. Obtaining reliable and comparable information about the occurrence of leptospirosis in populations, and detecting changing trends, are critical for setting policy and public health priorities. Traditional sources of information about the descriptive epidemiology, the disability attributed to leptospirosis infection, and associated risk factors are generally incomplete, fragmented and of uncertain reliability and comparability. Therefore, the global burden of disease concept and methodological framework will be used by the World Health Organization's (WHO) initiative to estimate the global burden of human leptospirosis. The aim of the initiative is to quantify and compare the health of populations by a summary measure of both mortality and disability, the disability-adjusted life year (DALY). WHO has established the Leptospirosis Burden Epidemiology Reference Group (LERG) to coordinate the assessment. The burden estimates provided by the LERG will guide public health policy on leptospirosis disease control and prevention, with the aim of reducing the impact on human health.