Raccoon Roundworm

Why in news?

Scientists have reported the spread of raccoon roundworm across multiple European countries. The parasite, originally from North America, has been carried by introduced raccoon populations and is now prevalent in Germany, Luxembourg and other countries. Health experts warn of potential risks to people and wildlife.

Background

Raccoon roundworm, scientifically known as Baylisascaris procyonis, is a parasitic nematode. Adult worms live in the intestines of raccoons and release millions of eggs in the animals’ droppings. In North America, many raccoons carry the parasite without obvious illness. The eggs become infective after 2–4 weeks in the environment.

Life cycle and transmission

• Definitive host: Raccoons ingest infective eggs from the environment. Larvae hatch in the intestine, mature into adults and lay eggs that are shed with feces. A single raccoon can produce millions of eggs daily.
• Environmental persistence: The eggs are extremely hardy and can survive in soil for years. They become infectious after being exposed to warmth and moisture for several weeks.
• Accidental hosts: Other mammals and birds, including humans, can accidentally swallow eggs by contacting contaminated soil, water or objects. In non‑raccoon hosts, larvae migrate through tissues rather than developing into adult worms.
• Human disease: Humans are accidental hosts. Once ingested, larvae can migrate to the liver, eyes and brain, causing visceral, ocular or neural larva migrans. Symptoms range from fatigue and confusion to vision loss and severe neurologic disease. Children and individuals with close contact to raccoon habitats are at higher risk.

Recent findings

• A study involving more than 500 raccoons in Germany found that over 66 percent carried the parasite, suggesting the population may be an important reservoir.
• Reports indicate the roundworm has been detected in at least nine European countries, including Belgium, Poland and Switzerland, largely due to raccoons imported for fur farming and subsequently released or escaped.
• Human cases in Europe are rare but may be underdiagnosed because symptoms resemble other neurological diseases. Health agencies recommend avoiding contact with raccoon latrines and practising hand hygiene after outdoor activities.