Worms in humans (2024)

What is worm infection in humans?

Many types of worms can cause problems in humans.

In Australia, worms that may infect people include:

• threadworms (enterobius vermicularis)
• tapeworms
• whipworms
• hookworms
• strongyloides

These intestinal worms are parasites. This means that they survive by living in or on another living thing (the host) and getting their food from it.

The most common worm infection in Australia is threadworms.

What are the symptoms of a worm infection?

Symptoms of threadworms

The most common symptom of threadworms an itchy bottom.

This is because threadworms come out of the anus at night to lay their eggs between the buttocks, causing extreme itching around the bottom and vagin*. They look like small white threads moving about and may be seen with a torch. The threadworms may also be seen on the surface of the stools (poo), if a person has a heavy infestation.

Children with threadworms may also be irritable, have poor sleep and poor appetite. You may notice redness and scratch marks around their bottom.

Symptoms of other worm infections

Other types of worms may not cause any symptoms for example pork and beef tapeworms or strongyloides stercoralis. Other types of worms, such as dog tapeworm, may only cause symptoms after a long time, or if there is a severe infection.

Symptoms may include:

• diarrhoea
• tiredness and weakness
• abdominal pain
• weight loss
• anaemia.

Once they have entered humans by penetrating the skin, the larvae of some worms, for example dog hookworm (ancylostoma caninum) or strongyloides, can migrate under the skin. This can cause diagnostic pink or red curving tracks known as larva migrans or larva currens.

The tracks may be raised and cause intense itching. There may be tingling or prickling half an hour after the larvae penetrate the skin.

How do you get worms?

Threadworms

Threadworms are usually acquired by ingesting (eating) the eggs.

Humans are the only host of threadworms. The adult worms live in the lower intestine, coming out of the anus at night to lay their eggs. Children with threadworms can get the eggs under their fingernails when scratching an itchy bottoms at night. The eggs can then be spread through bed linen, bathroom fittings and other items, even food. The eggs can survive for around 2 weeks like this on surfaces.

Other worms

Some other types of worms enter humans when their larvae penetrate the skin, often through bare feet.

Dog hookworms can be caught like this through the skin. This commonly happens by being barefoot outdoors and coming into contact with larval hookworms in soil or sand contaminated with stool from an infected dog.

Strongyloides, a roundworm, also infects humans when its larvae penetrate the skin. Pork tapeworm (taenia solium) and beef tapeworm (taenia saginata) can be acquired from eating undercooked meat containing cysts of the tapeworm larvae. These infections are not common in Australia and are usually only acquired overseas.

Dog tapeworms (echinococcus granulosus) are another type of tapeworm. They can infect humans who accidentally ingest the tapeworm’s eggs, which are released from dog or dingo stools. The tapeworm sheds segments into the animal’s stool, which then rupture (break), releasing the eggs. The eggs can contaminate a dog’s coat, kennel, and fields and play areas. A person may then ingest an egg and become infected. Patting an infected dog may be enough to get infected.

Dog tapeworm can cause a serious disease in humans, known as hydatid disease.

Dwarf tapeworms (nana) are acquired by ingesting dwarf tapeworm eggs. The infection can also be transmitted between people in areas with poor sanitation and hygiene.

Whipworm (trichuris trichiura) infection can occur if a person ingests the eggs from contact with infected soil, or by eating foods grown in soil that contains whipworm eggs.

How are worms diagnosed?

Threadworms

Threadworms can be diagnosed by a ‘sticky tape test’ available from your doctor. The test detects threadworm eggs that are deposited around the anus at night. It involves using special sticky tape to take a sample first thing in the morning. The sticky tape is pressed onto the area around the anus, causing any threadworm eggs present to stick to the tape. The doctor or a laboratory will examine the tape under the microscope to look for the eggs.

Other worms

Other types of worms may be diagnosed in the laboratory from a fresh stool sample. For example, tapeworms are diagnosed by finding worm segments or worm eggs in a stool sample. Other worms are diagnosed by the presence of eggs, larvae or the parasites themselves in the stool sample.

Dog hookworm may be diagnosed by finding the parasite on a gut biopsy specimen. The characteristic rash of larva migrans on the skin can also indicate infection with dog hookworm. If this rash moves very quickly (2 – 10 cm per hour) then it is known as larva currens, and indicates infection with strongyloides.

Infection with some parasites, for example strongyloides, may cause eosinophilia, an increase in a type of white blood cells known as eosinophils.

What do intestinal worms look like?

Intestinal worms that infect humans and their larvae vary in appearance and size, such as the following:

• Threadworms — These worms are like tiny white moving threads 2 – 13 mm long; they are visible to the naked eye.
• Strongyloides — The larvae are microscopic in size, but mature into 2 – 3 mm long worms
• Dog hookworm — The eggs may be seen as tiny white eggs in a dog’s faeces; the adult worms are 12 – 15 mm long and j-shaped (hook shaped), with a large mouth with teeth.
• Dog tapeworm — This tapeworm has 3 – 4 segments and is around 6 mm long.
• Pork and beef tapeworms — These are large and flat, like a ribbon; adult pork tapeworms may reach 2 – 7 metres in length; adult beef tapeworms may be 4 – 12 metres long. Tapeworms have a head, a neck and many segments, which may contain eggs.
• Dwarf tapeworms — these are 2 – 4 cm long and 1 mm wide.
• Whipworms — adult worms are around 4 cm in length, with one end that is broad and the other thin, making them look like a whip.

How is a worm infection treated?

The treatment for threadworms is worming tablets, which are available from the pharmacy. The whole household should be treated at the same time, even if they have no symptoms. When taking the medicine, you should also ensure you follow strict hygiene practices to prevent reinfestation.

Other intestinal worm infections are also treated with medicines that kill the parasite without harming the person. Your doctor or a gastroenterologist (gut specialist) will advise on the best medicine and the right dose. The worms then usually pass out of the body.

Hydatid disease, caused by dog tapeworm, is serious and potentially fatal. It can cause cysts to from in the liver, lungs, spleen or kidneys, and rarely the brain. Removal of the cysts requires tricky surgery and medicines.

Can a child with worms go to daycare or school?

Children with worms can still go to daycare or school if they have been treated, unless they have loose bowel motions.

How can I prevent infection with worms?

Good hand hygiene and keeping fingernails short is the best way to reduce your chance of catching threadworms.

Aside from threadworms, most worm infections in Australia occur in rural and remote communities, or in travellers returning from overseas. They are more common in tropical or subtropical areas. To avoid these types of worms:

• Always wash your hands after gardening and before eating, drinking and smoking.
• Always wash fruit and vegetables before eating.
• Cook beef and pork thoroughly.
• Wear shoes on moist, sandy soil or soil that may be contaminated with dog faeces.

When looking after your dog, make sure you:

• Wash your hands after handling dogs.
• Supervise dogs so that they can’t feed on dead stock or wild animals.
• Do not feed offal to your dog.
• Ensure your dogs are regularly dewormed, with worming tablets.

Resources and support

For more information about threadworms in children see the Royal Children’s Hospital website.

Call healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.