People become infected when they accidentally ingest infective eggs in soil, water, or on objects that have been contaminated with raccoon feces. Baylisascaris infection is not spread from one person to another. When humans ingest these eggs, they hatch into larvae in the person's intestine and travel throughout the body, affecting the organs and muscles.
Depending on where the larvae migrate, Baylisascaris infection can affect the brain and spinal cord (neural larva migrans), the eye (ocular larva migrans), and/or other organs (visceral larva migrans).
Signs and symptoms depend on how many eggs are ingested and where in the body the larvae migrate (travel). Ingesting a few eggs may cause few or no symptoms, while ingesting large numbers of eggs may lead to serious symptoms. Symptoms of infection may take a week or so to develop and may include:
- Liver enlargement
- Loss of coordination
- Lack of attention to people and surroundings
- Loss of muscle control