Leptospirosis Burden Epidemiology Reference Group (LERG)

The Global Burden of Leptospirosis

What do we know?

Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira. It is most commonly spread via water contaminated with urine from infected animals, but contaminated food or soil can also act as vehicles for the disease. The main animal reservoirs are rodents, livestock and dogs. Disease in humans can vary from mild flu-like illness to serious disease. Some severe complications include kidney damage, liver failure, respiratory distress, meningitis and death.

Although Leptospirosis can occur worldwide, there are a number of risk factors associated with the disease. It is most common in urban slum areas, where there is inadequate sewage disposal and water treatment. It can also be an occupational hazard for those working outdoors or with animals and a recreational hazard for those participating in water-related activities. Epidemics are typically seen during flooding, and changing environmental trends, with extreme weather patterns, may perpetuate these epidemics.

Family wading through flood waters with supplies
Regional Medical Research Centre/Port Blair/India

Did you know?

  • The actual incidence of Leptospirosis in Hawaii is estimated to be double the reported incidence.
  • A study in Peru demonstrates high levels of under-diagnosis of Leptospirosis and under-recognition of severe complications especially in urban areas.
  • A study from Gabon shows that over 15% of people in slum communities show evidence of infections with Leptospira.
  • Unusual flooding in Bangladesh, India, and Sri Lanka caused overflowing of rodent-infested sewers exposing inhabitants to Leptospirosis infection.
  • Leptospirosis soared across Central America following Hurricane Mitch (1998).
  • Global travel to high-risk areas increases the exposure of individuals to Leptospirosis.

What do we still need to know?

Very little is currently known regarding the true incidence of Leptospirosis. It is estimated that 0.1 to 1 per 100 000 people living in temperate climates are affected each year, with the number increasing to 10 or more per 100 000 people living in tropical climates. If there is an epidemic, the incidence can soar to 100 or more per 100 000 people. The disease is underreported for many reasons, including difficulty in distinguishing clinical signs from those of other endemic diseases and a lack of appropriate diagnostic laboratory services.