Causes of Lassa fever

Learn about the causes of Lassa fever, how it’s spread and where it is found.

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Cause Lassa fever

Lassa fever is caused by the Lassa virus, which is an Arenavirus.

How Lassa fever is spread

Lassa fever is spread by:

  • person-to-person contact
  • rodents

People become infected with the Lassa virus by:

  • touching rodent urine and droppings
  • inhaling dust particles of rodent droppings
  • touching contaminated objects or eating contaminated food
  • eating infected rodents

People can also get Lassa virus from person-to-person contact by touching infected:

  • blood
  • tissue
  • body fluids, such as:
  • urine
  • saliva
  • vomit
  • semen

The virus doesn’t spread through casual contact where body fluids are not exchanged, such as shaking hands.

Exposure can occur in health care settings when staff do not exercise appropriate precautions, including the use of protective equipment, such as:

  • masks
  • gowns
  • gloves

This medical equipment must be properly disposed of or sterilized to reduce the spread of Lassa virus.

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