What is a worm infection in humans?

Many types of worms can cause health problems in people. The most common worm infection in Australia is threadworms (also called pinworms or enterobius vermicularis).

Other worms that can infect people include:

• tapeworms
• whipworms
• hookworms
• strongyloides

These worms live in your intestines (guts) and are parasites. Parasites live in or on another living thing (called the host) and get their food from it.

What do intestinal worms look like?

Intestinal worms that can live in your gut come in different shapes and sizes, such as:

• Threadworms — These worms look like tiny white moving threads. They are 2 to 13 mm long.
• Dwarf tapeworms — These are 2 to 4 cm long and 1 mm wide.
• Whipworms — Adult whipworms are about 4 cm long. One end is wide and the other end is thin, so they look like a whip.
• Dog hookworm — The tiny white eggs may be seen in a dog's faeces (poo). The adult worms are 12 to 15 mm long. They have a j-shaped or hook shaped body, and a large mouth with teeth.
• Dog tapeworm — This tapeworm has 3 to 4 parts and is about 6 mm long.
• Pork and beef tapeworms — These are large and flat, like a ribbon. Adult pork tapeworms can grow to be 2 to 7 metres long, while adult beef tapeworms can be 4 to 12 metres long. Tapeworms have a head, a neck and many parts that may contain eggs.
• Strongyloides — The larvae (young form) are microscopic in size but grow into worms that are 2 to 3 mm long.

What are the symptoms of a worm infection?

Symptoms of threadworms

The most common symptom of threadworms is an itchy bottom.

This is because threadworms come out of your anus at night to lay their eggs between your buttocks, causing itching around your bottom and vagina. 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 trouble sleeping and not want to eat. You may see red spots and scratch marks around their bottom.

Symptoms of other worm infections

Other types of worms, for example pork and beef tapeworms or strongyloides stercoralis, may not cause any symptoms

Some 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 a person by breaking their skin, the larvae of some worms, like dog hookworm (ancylostoma caninum) or strongyloides, can move around under the skin. This can cause pink or red lines on the skin called larva migrans or larva currens.

The lines might stick up and make you itch a lot. You might feel a tingling or prickling sensation soon after the larvae get into your skin.

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How do you get worms?

Threadworms

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

Adult threadworms live in your lower intestine, coming out of your anus (bottom) at night to lay their eggs. Children with threadworms can get the eggs under their fingernails when they scratch their itchy bottoms at night. The eggs can be found on bed linen, bathroom items and food. The eggs can live on surfaces for about 2 weeks.

Other worms

Some types of worms infect people when their larvae (young stage of worms) go through their skin, often through bare feet. These include:

• Dog hookworms — these larvae can get in through the skin when you walk barefoot outside and touch soil or sand containing infected dog stool (poo).
• Strongyloides — larvae from this roundworm can also infect you by entering the skin.

You can get pork tapeworm (taenia solium) and beef tapeworm (taenia saginata) infections by eating undercooked meat containing cysts of the larvae. You can also get trichinosis (trichinellosis) by eating pork or pork products that are undercooked. These infections are not common in Australia and usually happen only when you travel overseas.

Dog tapeworms (echinococcus granulosus) can infect you if you accidentally swallow the eggs, which might come from dog or dingo stools. The tapeworm releases segments into the animal's stool, which then break apart and let out the eggs. The eggs can appear in a dog's coat, kennel, and places where it plays. Patting a dog that has tapeworms may be enough to get infected. Dog tapeworm can cause a serious disease in humans, known as hydatid disease.

Dwarf tapeworm (nana) infections may be caused by swallowing dwarf tapeworm eggs. The infection can also be spread between people in areas with poor sanitation and hygiene.

Whipworm (trichuris trichiura) infection can happen if you swallow the eggs, which can come from touching infected soil or eating food that has been grown in that soil.

Dog or cat roundworm can cause toxocariasis. This infection doesn't usually show any symptoms. But some people may have a fever, cough, abdominal (tummy) pain and eye problems. You can get toxcariasis by touching dog and cat poo or contaminated soil.

Ascaris infection can happen if you swallow soil that has eggs from the ascaris worm. Not everyone gets symptoms, but it can cause discomfort or pain in your abdomen (tummy). It's rare to get ascaris infection in Australia but common in overseas tropical regions.

When should I see my doctor?

See your doctor if you have tried a threadworm treatment and your symptoms have not improved. Your doctor will examine you and may want to do blood or faeces (poo) tests. Also see your doctor if you:

• pass a large worm in your stool
• have tummy pain, nausea, vomiting or feel very tired

See your doctor if you have signs of a roundworm, hookworm or tapeworm infection, such as:

• seeing a large worm, a part of a worm or worm eggs in your stool
• having diarrhoea or a tummy ache for more than 2 weeks
• having a red, itchy rash on your skin, which is shaped like a worm
• losing weight for no reason

Worm infections other than threadworm are usually caught while travelling. Symptoms can take a while to show. Let your doctor know if you have been overseas in the past 2 years.

How are worms diagnosed?

Threadworms

Your doctor or pharmacist will ask questions about your symptoms if they think you might have threadworms. Your doctor may examine you.

Threadworms can also be diagnosed by a 'sticky tape test'. The test looks for threadworm eggs that are laid around the anus at night. You use the tape to collect a sample first thing in the morning. You press the sticky tape around your anus, which makes any threadworm eggs stick to the tape. Your doctor can send this sample to a laboratory to check for eggs using a microscope.

Other worms

Other types of worms can be identified in the laboratory from a fresh stool sample. Tapeworms are diagnosed by looking for worm segments or worm eggs in a stool sample. Other worms are diagnosed by looking for eggs, larvae or worms in a stool sample.

The rash from larva migrans on the skin can also show that a person is infected with dog hookworm. If this rash moves very quickly (2 to 10 cm every hour), it is called larva currens and shows that there is an infection with strongyloides.

Some parasites, like strongyloides, can cause eosinophilia, which is an increase in the number of eosinophils (a type of white blood cells) in your blood .

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How are worm infections in humans treated?

The treatment for threadworms is worming tablets, which are available from a pharmacy without a prescription. Everyone in the household should be treated at the same time, even if they don't have symptoms. When you take the medicine, make sure you follow strict hygiene practices to prevent reinfestation.

Other intestinal worm infections are treated with other medicines that kill the worms without harming you. The worms then usually pass out of your body. Your doctor or gastroenterologist (specialist in diseases of the digestive system) will recommend which medicine and how much to take.

Hydatid disease, which comes from dog tapeworms, is a serious illness that can sometimes be deadly. It can cause cysts to form in your liver, lungs, spleen or kidneys, and sometimes in the brain. Removal of the cysts needs careful surgery and medicine.

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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.

Besides threadworms, most worm infections in Australia happen in rural and remote areas, or in travellers coming back from other countries. They are found more often in tropical or subtropical areas. To avoid these types of worms:

• Always wash your hands after gardening and before eating and drinking.
• 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 you touch dogs.
• Keep an eye on dogs so that they can't feed on dead animals or wild animals.
• Don't feed offal to your dog.
• Regularly deworm your dogs with worming tablets.

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 diarrhoea.

Resources and support

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

Languages other than English

• The Royal Children's Hospital also has information about threadworms in languages other than English.

Call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.