The Raccoon roundworm, Baylisascaris procyonis, is an internal parasite of raccoons. The parasite lives in the intestinal tract of raccoons and generally does not harm the raccoon unless the raccoon is otherwise debilitated.
Adult worms living in the intestines of raccoons release parasitic eggs in raccoon feces. The eggs may be found on the ground or in the surrounding vegetation. Eggs can survive in traps, caging or other enclosures used for captive raccoons. Other animals, especially woodchucks, rabbits and squirrels become infected by ingesting eggs from contaminated vegetation or other surfaces. Once the eggs are ingested, they can hatch into larvae. The larvae can move through the body, causing harm to the nervous system or eyes and can even occasionally result in death.
Raccoons may show no signs of having roundworms. In other wildlife, if the larvae migrate to the brain, signs may include a head tilt, walking in circles, falling over and seizures.
Raccoon roundworms are very hardy and can only be killed by intense heat. The eggs do not become infective until 10-14 days after the raccoon defecates, so prompt clean-up of raccoon feces lessens the risk of exposure.
People can become infected by accidentally ingesting eggs from contaminated surfaces, including unwashed hands. Children are at the greatest risk because they tend to put their fingers in their mouths and play in areas where raccoons may have defecated. There is no reliably successful treatment to rid the roundworms in people.
Homeowners should take steps to discourage raccoons from visiting and nesting in areas used for personal recreation such as gardens and backyards, especially where children play. Raccoons tend to use “latrines” and any accumulated raccoon feces should be carefully removed and burned or buried. Gloves and a mask should be worn when handling raccoon fecal material or anything that may have been contaminated with raccoon feces.