Roundworms are worms that can infest the human digestive tract, specifically the small intestine. As the Latin name for roundworms is Ascaris lumbricoides, a roundworm infection is also sometimes known as ascariasis.
In most people, a roundworm infection does not cause any noticeable symptoms.
When symptoms do occur, they include a high temperature and dry cough 4-16 days after swallowing the eggs. You may have mild abdominal pain, vomiting and diarrhoea later on. See Roundworm - symptoms for more information.
Roundworms are parasites. This means that they use the human body to stay alive, feed and reproduce.
How infection occurs
A roundworm infection can occur if someone swallows ascaris eggs in contaminated food or water. It is also possible for someone to transfer eggs from their hands to their mouth if they touch contaminated soil and do not wash their hands before eating.
After the eggs mature into adult worms, the worms produce more eggs. The eggs are released from the body through the bowel and can then infect other humans.
How common are roundworm infections?
Roundworm infections are one of the most common health conditions in the world. It is estimated that 1.4 billion people (a quarter of the world's population) currently have a roundworm infection.
Roundworm infections are most widespread in tropical and sub-tropical areas, particularly in parts of the world that are overcrowded and have poor sanitation.
It is estimated that the global distribution of cases of roundworm is as follows:
- 75% of cases are in Asia and Oceania.
- 17% of cases are in Africa and the Middle East.
- 8% of cases are in Central and South America and the Caribbean.
Ascaris eggs thrive in warm, moist soil. Children are more likely to develop a roundworm infection than adults because they are more likely to come into contact with contaminated soil when playing.
The ascaris parasite is not native to Ireland. This means that any cases of roundworm recorded in Ireland were contracted abroad, either by travellers or migrants coming to Ireland from parts of the world where roundworm is present.
In Ireland, the outlook for people who are treated for a roundworm infection is excellent. A range of very effective medications can be used to kill the roundworm.
If a very large number of eggs have been ingested, or if the worms move from the small intestine to other parts of the body, they can cause serious complications such as a bowel obstruction.
However, in Ireland these types of roundworm complications are very rare.