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Food poisoning: Accidentally eating worms, is it serious?

A person can accidentally ingest worms if they eat spoiled food contaminated with fly larvae. Accidental ingestion of worms is usually nothing to worry about, but can sometimes lead to health complications, such as bacterial poisoning.

A maggot is the larva of a common housefly. The worms are between 3 and 12 millimeters long, have no legs, and are white or cream in color. An adult female house fly can lay up to 130 eggs at a time, each of which will hatch into a single larva. Flies lay their eggs in decaying organic matter, such as spoiled food and animal waste, which serves as food for the developing larvae.

In this article, we explore some of the potential health effects of eating worms and explain what to do and when to seek medical attention after accidentally ingesting one. We also looked at whether people intentionally eat worms and whether this practice is safe.

bacterial poisoning

Food poisoning is a potential risk of eating worms. Flies can visit multiple food sources throughout the day and can carry harmful bacteria that they pick up from human or animal waste. They can spread these bacteria to the food that people eat.
Larvae that develop in contaminated food can ingest these bacteria. People who eat these contaminated foods or the larvae are also exposed to the bacteria and can get sick.

Salmonella and Escherichia coli are examples of bacteria that flies and worms can spread to humans.


Salmonella is one of the most common causes of foodborne illness. Symptoms of a Salmonella infection can include:

abdominal cramps
nausea and vomiting
Symptoms usually appear 12 to 72 hours after ingesting the bacteria, and the illness usually lasts 4 to 7 days.

People with Salmonella poisoning often recover without treatment. However, frequent vomiting and diarrhea can lead to severe dehydration and sometimes hospitalization. Therefore, people with Salmonella poisoning need to drink plenty of fluids, especially clear broths, and fruit juices, to replace lost fluids and electrolytes.

E. coli poisoning

There are many different strains of E. coli. Although most strains are harmless, some can make a person seriously ill.

Symptoms of an E. coli infection may include the following:

stomach cramps
diarrhea, which may contain blood
mild fever, usually less than 101°F

These symptoms usually appear 1 to 10 days after ingesting the bacteria and can last 5 to 7 days. The severity of an E. coli infection can range from very mild to severe and can sometimes even be life-threatening. As with Salmonella poisoning, it is essential to drink plenty of fluids to avoid dehydration.

intestinal myiasis

Myiasis occurs when a person is infested with fly larvae. The larvae live on or in the person and survive by feeding on their tissues.
Intestinal myiasis is a type of myiasis that can occur when a person ingests larvae that survive within the gastrointestinal tract. Some people with intestinal myiasis have no symptoms and only realize they are infected after noticing the larvae in their stool.

However, the symptoms of intestinal myiasis can be as follows

abdominal pain
nausea and vomiting
itchy anus
bleeding from the rectum

Myiasis is not common in Europe and tends to occur mainly in tropical and subtropical countries, including some countries in Africa and South America. However, one can get myiasis while traveling to these countries.

To do?

Accidental ingestion of worms usually does not cause lasting damage. However, if a person has ingested worms while eating spoiled food, they are at risk of food poisoning. Symptoms of food poisoning can range from very mild to severe and can sometimes last for several days.

People at higher risk of food poisoning include:

Small children
older adults
people with weakened immune systems, such as people undergoing organ transplants.

People with severe vomiting and diarrhea due to food poisoning must drink plenty of fluids to avoid dehydration.

When to see a doctor

A person should see a doctor if any of the following signs and symptoms appear after ingesting worms:

larvae visible in feces
persistent abdominal pain
symptoms of bacterial poisoning that worsen or do not improve
diarrhea that lasts more than 3 days
diarrhea and fever
bloody stools
signs of dehydration
severe or persistent vomiting

Do people intentionally eat worms?

In some countries, it is not uncommon to eat insects. Many people in countries outside of Europe and North America eat insects. Scientists estimate that there are about 2,000 species of edible insects. In addition to the insects themselves, the eggs and larvae of some species are edible.

Casu marzu is a Sardinian cheese that contains thousands of worms. At the start of cheese production, the cheesemaker removes the outer rind, which encourages flies to enter and lay their eggs. For several months, the larvae eat the rotten cheese. The droppings of the larvae give the cheese its unique, pungent flavor.

Due to the health risks of consuming live worms, the European Food Safety Authority has banned the sale of casu marzu. However, a small number of Sardinian farmers continue to make this cheese for personal consumption.

Can you eat worms safely?

Worms are particularly rich in protein and fat. Therefore, scientists are currently studying the possibility of cultivating, collecting, and processing fly worms for human consumption. They suggested heating, drying, and microwaving the larvae to reduce the risk of bacterial contamination. Currently, however, there is no guaranteed, risk-free way to consume worms safely.


For most people living in more temperate climates, accidental ingestion of worms is unlikely to cause harm. People can get temporary food poisoning after eating contaminated worms or spoiled food that contains them. However, most cases of food poisoning go away without treatment after several days. It is advisable to consult a doctor if severe or bothersome symptoms appear after accidental ingestion of worms.


Caparros Megido, R., et al. (2014). Acceptance of edible insects by Belgian consumers: promising attitude for the development of entomophagy [Abstract].

Chapter 6: Houseflies. (North Dakota).

Daeschlein, G., et al. (2015). Worms as a potential vector for pathogen transmission and implications for infection control in waste management.

* Presse Santé strives to transmit health knowledge in a language accessible to all. In NO CASE, the information provided can not replace the advice of a health professional.

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