Healthcare Workers

Technical Information for Leptospirosis

Clinical Features

Symptoms of leptospirosis include fever, headache, chills, muscle aches, vomiting/diarrhea, cough, conjunctival suffusion, jaundice, and sometimes a rash. The incubation period is usually 5-14 days, with a range of 2-30 days. If not treated, the patient could develop kidney damage, meningitis, liver failure, and respiratory distress. In some cases, death occurs.

Etiologic Agent

Leptospires are long, thin, motile spirochetes. They may be free-living or associated with animal hosts and survive well in fresh water, soil, and mud in tropical areas. Organisms are antigenically complex, with over 250 known pathogenic serologic variants. Although certain geographic regions contain specific leptospiral serovars and species, the serologic characterization of an isolate is not an absolute predictor of its species designation.


Clinical course is highly variable. Most cases involve flu-like symptoms (fever, chills, muscle aches, headaches). Other symptoms may include conjunctivitis, vomiting, diarrhea, stomach pain, jaundice, cough, and rarely, a skin rash. About 10 percent of people with leptospirosis develop severe disease, including kidney or liver failure, meningitis, difficulty breathing, bleeding, and meningitis. Case fatality rate is 5 to 15% in cases with severe clinical illness.


Leptospirosis has been reinstated as a nationally notifiable disease as of January 2013. The updated 2013 leptospirosis case definition is available here. Until CDC can receive extended electronic case information on leptospirosis, please continue to send case information to CDC using the case report form.

The case report form is available in English and Spanish as a fillable PDF form that can be completed electronically or can be printed and completed by hand. Completed forms can be emailed, faxed, or mailed to CDC.

Fact Sheet for Clinicians

women walking in flood water

Leptospirosis Fact Sheet for Clinicians contains information about the background, transmission, clinical findings, treatment, laboratory testing, sample submission, prevention, surveillance, and reporting of leptospirosis. The fact sheet is available in English and Spanish.

Incidence and Trends

  • It is estimated that 100-150 Leptospirosis cases are identified annually in the United States. About 50% of cases occur in Puerto Rico.
  • The largest recorded U.S. outbreak occurred in 1998, when 775 people were exposed to the disease. Of these, 110 became infected.
  • Although incidence in the United States is relatively low, leptospirosis is considered to be the most widespread zoonotic disease in the world.
  • It’s estimated that more than 1 million cases occur worldwide each year, including an about 59,000 deaths.

Laboratory Submissions

Find out more about laboratory submissions by visiting the Bacterial Special Pathogens Branch Laboratory Submissions.