Baylisascaris Life Cycle

Baylisascaris procyonis is a common roundworm infection in raccoons. The adult worm in the raccoon produces massive numbers of resistant eggs that are excreted in the feces and can survive in the environment for years. It is a serious hazard to young children who explore outside and place their fingers in their mouth.

In Raccoons

• Baylisascaris does not produce disease in the raccoon but in the raccoon the parasite complete its life cycle. Raccoons pick up the parasite by grooming each other with the infective eggs in their fur and by ingesting smaller animals like birds or rodents that may be infected with the Baylisascaris larvae.

In Other Animals

• The raccoon roundworm has been shown to infect nearly 100 different domestic and wild animals. These animals get infected with eggs during grooming or foraging for food where raccoon feces are close by. In animals other than raccoons, the egg hatches and the larvae move around the body and eventually lodge in the brain or other organ where it is fatal. The larvae do not mature to adults so eggs are never produced.

In Humans

• People, especially children, accidentally get infected from contact with raccoon feces. The eggs are ingested when contaminated fingers are placed in the mouth. Like other animals, the parasite does not mature in humans. The larvae migrates (larval migrans) and causes disease in various organs, eyes and brain causing blindness and death.

Raccoon Latrines

• Raccoons defecate in natural or man-made structures like woodpiles, tree stumps and roofs. These are called latrines and the raccoons habitually go to the bathroom there. The latrines are the main source of contamination and infection.

Prevention/Solution

• The way to prevent infection with Baylisascaris is to avoid raccoons and contact with feces. Keep an eye on children while playing outside near latrines.