Tapeworms: Symptoms in humans and how to avoid getting infected

In a medical first, a man died recently after a tapeworm inside him got cancer

A tapeworm (Phanie Agency/REX Shutterstock)

Recent reports of a man dying after a tapeworm growing inside him was found to be cancerous, and another being told he had only 30 minutes to live after discovering a tapeworm inside his brain have sparked interest in these parasitic creatures. But are they as dangerous as we have been lead to believe?

Tapeworms (or cestodes) are parasitic flatworms, typically living in the digestive tracts of animals and humans. Human infection is often caused by the inadvertent consumption of the tapeworm’s eggs through poor hygiene, food, water, raw pork, beef and fish containing traces of contaminated faeces.

Once inside the body the eggs develop into larvae, sometimes moving to other areas of the body such as the brain. These larvae cause a host of symptoms that are different from the fully-fledged adult tapeworms.

Growing up to 15 to 30 feet in length, adult tapeworms are longer than your average garden worm and are most often found in developing countries, rather than the UK.

Despite their size, these adult worms do not always cause symptoms. If they do, sometimes these symptoms are passed off for other illnesses. So how do you know if you have a tapeworm?

Depending on the type of tapeworm symptoms can include:

• ‘Rice like’ substance in a person’s stool. The worms are made up of segments, which can break apart and be passed through the digestive system and in to the loo

• Stomach pain, vomiting and diarrhoea, which are often mistaken for other illnesses

• Loss of appetite, malnutrition and weight loss, although infection from beef or pork tapeworms can cause an increase in appetite

• Fish tapeworms can cause vitamin B12 deficiency, which may lead to anaemia

• Dizziness

• Insomnia

• Jaundice

Unlike adult tapeworms the larvae are not confined to the intestine and instead newly-hatched worms can burrow through the intestine wall into the blood stream, from there they can travel and settle anywhere in the body.

In rare cases tapeworm larvae can be life-threatening and cause cysticercosis, where little cysts enclosing the larvae settle on organs causing swelling and normal function. These may then burst leading to anaphylaxis. If they move into the brain they can become particularly dangerous, affecting both cerebral function and the central nervous system.

Tapeworm larvae infection symptoms can include:

• Fever

• Allergic reaction to the larvae itself

• Headaches or seizures

• Abscess in the lungs that result in pain or coughing

Due to the fact that tapeworms are not always easily identified the infections they cause can be present for many years. Treatment involves medication over a period of several months. For tapeworms living in the gut medication will cause them to be passed in a person’s stool; however its eggs will be left untouched.

Tapeworm larvae are more complicated to treat in comparison and are reviewed on a case-to-case basis. In the case of the man who died after diseased cells from the worm grew into tumours, it is believed that the cells took hold due to a weakened immune system caused by HIV.

To help avoid getting infected by tapeworms make sure food is prepared, washed and cooked properly, which is especially important if you often come into contact with animals or are travelling to places where tapeworm infections are common.

Jodie Tyley is the editor of How it Works Magazine. Issue 79 is out now. Follow the magazine on @HowItWorksmag