About Baylisascaris


What is Baylisascaris?

Baylisascaris worms are intestinal parasites found in a wide variety of animals. Different species of Baylisascaris are associated with different animal hosts. For example, Baylisascaris procyonis is found in raccoons, and Baylisascaris columnaris is found in skunks. Cases of Baylisascaris infection in people are not frequently reported but can be severe. Baylisascaris procyonis is thought to pose the greatest risk to people because of the often close association of raccoons to human dwellings.

In what parts of the world is Baylisascaris found?

Baylisascaris procyonis has been identified in the United States, Europe, and Japan. Some evidence of infection in animals has been reported in South America.

In the United States, infected raccoons have been found in a number of states, especially in the mid-Atlantic, Midwestern states and West Coast states.

How do people get infected?

People become infected by ingesting infectious eggs. Most infections are in children and others who are more likely to put dirt or animal waste in their mouth by mistake.

How can I prevent Baylisascaris infection?

Eggs passed in raccoon feces are not immediately infectious. In the environment, eggs take 2 to 4 weeks to become infectious. If raccoons have set up a den or a latrine (places where raccoons defecate) in your yard, raccoon feces and material contaminated with raccoon feces should be removed carefully and burned, buried, or sent to a landfill. Care should be taken to avoid contaminating hands and clothes. Treat decks, patios, and other surfaces with boiling water or a propane flame-gun (exercise proper precautions). Prompt removal and destruction of raccoon fecesCdc-pdfpdf icon before the eggs become infectious will reduce risk for exposure and possible infection.

Do not keep, feed, or adopt wild animals, including raccoons, as pets.

Washing your hands after working or playing outdoors is good practice for preventing a number of diseases.

More on: Handwashing

What are the symptoms and signs of Baylisascaris infection?

The incubation period (time from exposure to symptoms) is usually 1 to 4 weeks. If present, signs and symptoms can include the following:

  • Nausea
  • Tiredness
  • Liver enlargement
  • Loss of coordination
  • Lack of attention to people and surroundings
  • Loss of muscle control
  • Blindness
  • Coma

What should I do if I think I am infected with Baylisascaris?

You should discuss your concerns with your health care provider, who will examine you and ask you questions (for example, about your interactions with raccoons or other wild animals). Baylisascaris infection is difficult to diagnosis in humans. There are no widely available tests, so the diagnosis is often made by ruling out other diseases.

How is Baylisascaris infection treated?

A health care provider can discuss treatment options with you. No drug has been found to be completely effective against Baylisascaris infection in people. Albendazole has been recommended for some cases.

If I have Baylisascaris infection, should my family members be tested for the infection?

Baylisascaris infection is not contagious, so one person cannot give the infection to another. However, if your family may have been exposed the same way you were (such as contact with or exposure to an environment contaminated with raccoon or exotic pet feces), they should consult with a healthcare provider.


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Page last reviewed: September 16, 2020