B virus can spread from infected macaque monkeys to people. Macaque monkeys commonly have this virus, and it can be found in their saliva, feces (poop), urine (pee), or brain or spinal cord tissue. The virus may also be found in cells coming from an infected monkey in a lab. B virus can survive for hours on surfaces, particularly when moist.

Increasingly, free-ranging macaque monkeys infected with B virus are a common source for potentially exposing people to this virus. Large colonies of these monkeys are present in some parks in Florida and Puerto Rico.  However, CDC has not received reports of people getting infected with B virus from these monkeys.  If you are in a place where there are macaque monkeys, you should stay away from them so that you do not get bitten or scratched. You should not touch or feed monkeys.

Most people will not come in contact with monkeys, so their risk of getting infected with B virus is very low. However, laboratory workers, veterinarians, and others who may be exposed to monkeys or their specimens have a higher risk of getting B virus infection. In recent years, many macaque attacks have been reported by people visiting temple parks in some countries in Asia, where macaques commonly roam freely. About 70 to 80% of these macaques have been found to be B virus positive, but there have not been any documented cases of B virus spreading to humans.

You can get infected with B virus if you:

  • are bitten or scratched by an infected monkey
  • get an infected monkey’s tissue or fluid on your broken skin or in your eyes, nose, or mouth
  • have a needle stick by a contaminated syringe
  • scratch or cut yourself on a contaminated cage or other sharp-edged surface
  • are exposed to the brain (especially), spinal cord, or skull of an infected monkey

Only one case has been documented of an infected person spreading B virus to another person.

Page last reviewed: January 30, 2019