• Zoonotic disease caused by Leptospira interrogans, a spirochete bacteria
  • Spread via contact with infected water; outbreaks common during increased rainfall or during floods



  • 100 to 200 annual U.S. cases; 50% in Hawaii
  • Estimated incidence 0.1 to 10/100,000 worldwide
  • Most cases occur in tropical climates; can occur in temperate areas
  • Outbreaks can occur following increased rainfall or during floods.

Etiology and Pathophysiology

  • Caused by L. interrogans, a spirochete harbored in mammals (usually rodents) and shed into water or soil
  • There are >25 serogroups and 250 serovars; illness severity not linked to type
  • Organism is inoculated through breaks in the skin or contact with mucous membranes.
  • Spirochetes migrate through the lymphatic and vascular system to cause disease.
  • Life cycle is completed when spirochetes infect the kidneys and urinary tract and are excreted into fresh water or soil.

Pregnancy Considerations

  • Disease can be spread transplacentally to cause fetal complications; risk of abortion as high as 50%
  • Leptospira can be transmitted through breast milk (1).

Risk Factors

  • Frequent animal contact (farmers, veterinarians, abattoirs)
  • Fresh water exposure (military personnel, aid workers, adventure racers)
  • Increased rainfall or floods, particularly in tropical environments

General Prevention

  • Avoid contaminated water.
  • Wear protective clothing/gear.
  • Consume clean water.

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