Dididi project

A simple guide for patients, families and communities.

👪 The main message

What you need to know	What you can do
Children and adults can get parasitic worm infections.	Ask a health worker about the risks where you live.
Some people have no signs of illness.	Do not rely only on how you feel.
Different worms need different tests and medicines.	Get advice about the right care.
Treatment does not always prevent a new infection.	Combine treatment with steps to reduce exposure.

You may have heard people talk about “worms” or “bilharzia”. These infections can affect people during everyday activities, such as playing, farming or using water. This guide explains some common worm infections linked to soil and freshwater. [1,2]

You do not need to know the name of a worm before asking for help. Tell a health worker what you have noticed and where you may have been exposed.

🔎 What is a parasitic worm?

A parasite is a living thing that lives in or on another living thing. A parasitic worm can live inside a person and cause illness. Health workers may use the word helminth, which means a parasitic worm.

These worms are different from the earthworms you see in a garden. Some live in the gut, where food is digested. Others live in blood vessels. The problems they cause depend on the type of worm. [1,2]

You cannot always see an infection. Tiny worm eggs or young worms may be too small to see without laboratory equipment. Not seeing worms in your stool does not prove that you have no infection. [1,3]

🌱 How can worms enter the body?

There are different routes. This table shows three important examples.

Route	What happens?	Everyday example
Through the mouth	Tiny eggs from contaminated soil reach the mouth and are swallowed.	Eating with unwashed hands or eating food contaminated with soil. [1]
Through the skin from soil	Some young worms enter through skin that touches contaminated soil.	Walking barefoot where soil contains hookworm or Strongyloides. [1,4]
Through the skin from freshwater	Young schistosome worms enter through skin touching infected water.	Bathing, swimming or working in a river or lake where infection occurs. [2]

Contaminated means that something harmful is present. Soil may contain parasites after being polluted with human stool. Freshwater can contain schistosome parasites released by certain snails. [1,2]

This does not mean that every patch of soil or every river contains worms. The risk depends on the place and the type of parasite.

For bilharzia, the parasite enters through the skin. A person can become infected without drinking the water. Water that looks clear may still contain parasites. [5]

👧 👨 👵 Who can be affected?

Both children and adults can be affected. The risk is linked to exposure, not simply to age. [1,2]

Person or activity	Possible exposure
Children playing outdoors	Contact with contaminated soil.
Children swimming or playing in freshwater	Contact with water containing schistosome parasites.
Farmers and people working outdoors	Contact with soil or freshwater.
People fishing or working in water	Contact with infected freshwater.
People washing clothes or bathing in rivers or lakes	Contact with infected freshwater.
Visitors and travellers	Exposure while visiting an area where infection occurs.

These are examples, not a list of everyone who can be affected. Local health workers can explain which infections are found in your area. [1,2,5]

Worm infections are more common where safe water and toilets are difficult to access. People may need to use the same river for work, washing and bathing. Infection is not a reason to blame someone or call them dirty. [1,2]

Everyone deserves respectful care. Ask for help even if you feel embarrassed or worry about what other people may say.

🩺 What signs might I notice?

Some people have no symptoms. Others feel unwell. Different infections can cause different signs. [1,4,6]

Possible sign	What to do
Repeated stomach pain or loose stool	Ask a health worker if it continues or keeps returning.
Tiredness or weakness	Ask for an assessment, especially if it affects daily activities.
Poor growth or ongoing illness in a child	Arrange a health assessment.
Itchy skin or a rash	Explain when it started and any soil or water contact.
Blood in urine	Seek medical advice promptly.
Blood in stool	Seek medical advice promptly.

These signs do not prove that you have worms. Many other illnesses can cause the same problems. A health worker can assess what is happening. [1,6]

Do not wait to see a worm before asking for help. You may need a test even when no worm is visible.

💧 What is bilharzia?

Bilharzia is another name for schistosomiasis. It is caused by a type of parasitic worm found in some freshwater areas.

Some people notice an itchy rash after exposure. Later symptoms can include fever, stomach pain or blood in stool or urine. Other people have few symptoms. Untreated infection can damage organs over time. [6]

Bilharzia can also affect the genital organs. In women, symptoms may include unusual vaginal bleeding, pain during sex or pelvic pain. Men can also have genital symptoms. These problems need medical assessment because other conditions can cause them too. [7]

Genital bilharzia is acquired from infected freshwater. It is not proof of a sexually transmitted infection. A health worker may still need to check for other illnesses. [2,7]

🙂 Can I have worms even if I feel well?

Yes. Some infections cause few or no symptoms. Feeling well does not always mean that no infection is present. [1,4]

A health worker may suggest a test because of where you live, where you have travelled or the water and soil you have touched.

In some areas, health services provide regular worm treatment to groups at risk. People may be offered this treatment even when they feel well. These programmes aim to reduce illness in the community. [8,13]

Ask the programme team who should receive the medicine and when. If you have symptoms, explain them rather than relying only on the next treatment campaign.

🧪 How does a health worker check for worms?

The health worker will ask questions first. They may examine you and suggest a test.

Test	What might happen?
Stool test	You provide a small stool sample in a container. The laboratory looks for signs of infection.
Urine test	You provide a urine sample. This can help find some types of bilharzia.
Blood test	A small blood sample may help investigate certain infections.

The right test depends on the infection being considered. One test cannot find every kind of worm. [3,9]

If you need to provide a sample, ask for clear instructions. Check which container to use, how to collect the sample and when to bring it back. Ask someone to explain again if you are unsure.

A sample is not a judgement about you. It is information that helps the health worker choose care.

📋 What if the first test finds nothing?

Sometimes one sample misses an infection. A health worker may ask for another sample or a different test. This can happen when only small numbers of parasites are present or when the test is done too early. [3,9]

A result that finds no infection is useful, but it must be considered alongside your symptoms and exposure.

Before leaving, ask:

When will I get the result?
How will I receive it?
What should I do if I still feel unwell?
Do I need another visit or another sample?

Return for advice if symptoms continue or get worse. Another illness may need investigation, even if worms were not found.

💊 Can worm infections be treated?

Many worm infections can be treated with medicine. The medicine depends on the type of worm and the person receiving treatment. [1,2,10]

One medicine does not treat every worm infection. Tell the health worker about medicines you have already taken, including treatment at school or in a community programme.

Before treatment	After treatment
Say if you are pregnant or breastfeeding.	Follow the instructions you were given.
Explain other illnesses and medicines.	Attend any follow-up visit requested.
Give a child’s age and weight if known.	Return if symptoms continue or worsen.
Ask how to take the medicine.	Do not assume that treatment prevents future infection.

Do not choose a medicine only because it helped someone else. Ask a qualified health worker or an authorised treatment programme. Do not use medicines intended for animals.

⚕️ Tell the health worker before certain medicines

One worm, called Strongyloides, can remain in the body for a long time. It can become dangerous when certain medicines weaken the body’s ability to fight infection. [4,10]

Tell the health worker if you have lived in or visited a place where these worms occur, even if that was years ago.

This matters especially before medicines called corticosteroids, or other treatment that reduces the body’s defences. The health worker can decide whether you need a test or treatment for worms. [10]

Do not stop prescribed medicine on your own. Contact the person treating you and explain your possible exposure. Take your medicine list or packaging to the appointment if available.

👟 What can help reduce the risk?

Some actions reduce contact with parasites. They work best when communities also have reliable water, toilets and healthcare.

Picture cue	Action
🧼 Clean hands	Wash with soap and safe water after using the toilet and before preparing or eating food.
🥬 Food	Wash or prepare food safely. Avoid eating unwashed produce contaminated with soil.
🚻 Toilet	Use a toilet or latrine when available.
👟 Shoes	Wear shoes when walking on soil that may be contaminated.

These steps help reduce the risk of infections linked to soil. [13]

For bilharzia, avoid swimming, bathing or wading in freshwater known to carry the infection when possible. Ask local health workers which water sources are safer. Clear-looking water is not proof of safety. [5,11]

If you must enter water for work or daily needs, explain this to the local health team. Ask about safer water access and the treatment programmes available. Advice needs to fit the choices people actually have.

🔄 Can I become infected again?

Yes. Treatment can remove an infection, but it does not always protect you from the next exposure. A person can become infected again through contaminated soil or infected freshwater. [1,2]

That is one reason why some communities receive repeated treatment. Safe water, toilets and measures to reduce exposure are also important. [8]

If you become unwell again, tell the health worker when you last received medicine and whether you have had new soil or water contact.

Do not blame yourself if you become infected again. Ask what support and protection are possible where you live.

🚑 When should I get urgent help?

Seek urgent medical care for:

Very severe stomach pain.
Trouble breathing.
Fainting, confusion or extreme weakness.
A large amount of blood in stool or vomit.
A child who is very unwell, unusually sleepy or unable to drink.

These signs can have many causes. Do not wait for a worm test before seeking help.

Blood in urine also needs prompt assessment, even if it is painless. Do not assume it is normal because other people in the community have experienced it. [6]

If you are unsure how urgent a problem is, contact a health worker and explain the symptoms.

🗣️ What should I tell the health worker?

Use this checklist. You can ask someone you trust to help you remember the details.

My symptoms: What changed, and when did it start?
My water contact: Have I swum, bathed, washed or worked in rivers or lakes?
My soil contact: Have I walked barefoot or worked with soil?
Where I have lived: Include earlier homes and travel.
My treatment: Have I taken worm medicine before? When?
My medicines: Include prescribed medicines and other products.

You can say: “Could a worm infection be causing this? Do I need a test?”

You can also say: “I did not understand. Please explain again in a language I understand.” Ask whether interpretation or translated information is available.

🤝 How is DIDIDI helping?

DIDIDI is a research project working on ways to make worm testing more affordable and practical in rural African communities.

The project is developing tools to help detect infections and share useful information with health services. It is also studying how changes in climate relate to infection risks. The tools need to be tested carefully before wider use. [12]

If you are invited to a research study, ask what it involves, whether it is voluntary and how your information will be protected. Ask how you will receive results and what care is available.

You should still use your usual health service when you need advice or treatment.

✅ Five messages to remember

	Message
👪	Children and adults can be affected.
🌱 💧	Some worms enter through contaminated soil or infected freshwater.
🙂	You can have an infection without feeling ill.
🧪	The right test helps the health worker choose the right care.
💊	Treatment and reducing exposure both matter.

If you are worried, speak with a health worker. You do not need to know the name of the infection to ask for help.

Sources

These sources support the information above. You do not need to read them before asking for care.

World Health Organization. Soil-transmitted helminth infections. WHO.
World Health Organization. Schistosomiasis. WHO.
Centers for Disease Control and Prevention. Clinical Testing and Diagnosis for Schistosomiasis. CDC.
Centers for Disease Control and Prevention. About Strongyloides. CDC.
Centers for Disease Control and Prevention. About Schistosomiasis. CDC.
Centers for Disease Control and Prevention. Symptoms of Schistosomiasis. CDC.
World Health Organization. Schistosomiasis: Genital manifestations. WHO.
World Health Organization. WHO guideline on control and elimination of human schistosomiasis. 2022. WHO.
Nikolay B, Brooker SJ, Pullan RL. Sensitivity of diagnostic tests for human soil-transmitted helminth infections: a meta-analysis in the absence of a true gold standard. International Journal for Parasitology. 2014;44(11):765–774. PubMed.
Centers for Disease Control and Prevention. Clinical Care of Strongyloides. CDC.
Centers for Disease Control and Prevention. Preventing Schistosomiasis. CDC.
DIDIDI consortium. Project description. DIDIDI.
Centers for Disease Control and Prevention. About Soil-transmitted Helminths. CDC.

Information checked on 13 October 2026.