Gastroenteritis Amoebiasis

Overview

Amoebiasis (say: am-ee-BYE-uh-sis) is an infection in the gut caused by a tiny parasite called Entamoeba histolytica. It is far too small to see without a microscope. You catch it by swallowing food or water that has been contaminated with very small amounts of infected poo, or by putting contaminated hands or objects in your mouth. Many people who swallow the parasite never feel unwell at all. Others get diarrhoea, tummy cramps and sometimes blood or slime in their stool. It is not the same as the common 'stomach bug' caused by viruses — this parasite usually needs specific treatment to clear it properly.

It is common around the world, especially in places where clean water and good toilets are hard to find. In countries with strong sanitation it is uncommon, and when it does appear it is usually linked to travel, to living or working abroad, or to a local outbreak from contaminated water or food.

Anyone can get amoebiasis, but it is seen most often in people living in or travelling to tropical and subtropical regions with poor sanitation. Young children in these areas are especially at risk of getting dehydrated. People who move between countries, people in shared living settings, and people who have unprotected anal sex are also more likely to be exposed.

Symptoms

Common symptoms

• Watery or loose diarrhoea that may contain blood, mucus or a jelly-like slime
• Stomach cramps and pain, often worse on the lower right side or above the pubic bone
• An urgent need to rush to the toilet, even when there is little to pass
• Feeling sick or being sick
• Mild fever and feeling generally run down or tired
• Losing weight without trying, or losing your appetite
• Gas and bloating

Symptoms in children

• Irritability, crying more than usual, or being unusually sleepy and hard to wake
• Fewer wet nappies or fewer trips to the toilet for a wee
• A dry mouth, no tears when crying, or sunken eyes
• Refusing feeds or drinks, or being sick after them
• Loose, smelly stools that may have blood in them
• Fever and a tummy that looks swollen

Symptoms in older adults

• Feeling weak, wobbly or more confused than usual — this can be a sign of dehydration
• Diarrhoea that leads to dizziness on standing because of fluid loss
• Not feeling thirsty, so drinking less than the body needs
• A fever that is low or missing entirely, even when the infection is serious
• Tummy pain that is hard to describe or pinpoint

Causes

Main causes

• Drinking water or eating food that has been contaminated with the parasite
• Eating fruit or vegetables that were washed in unsafe water or handled with unclean hands
• Contact with infected poo, for example through a shared toilet, nappy changing, or poor handwashing
• Sexual contact that puts the mouth near the bottom of someone who is infected
• Flies and cockroaches carrying the parasite onto uncovered food

Risk factors

• Living in, or travelling to, parts of the world with limited clean water and poor sanitation
• Caring for someone with diarrhoea or changing nappies without good hand hygiene
• Working in a setting where food is prepared for many people
• Living in shared accommodation, such as a care home, hostel or barracks
• Having a weakened immune system, which can make symptoms more severe
• Being a man who has sex with men, as some intestinal infections spread more easily in this group

When to see a doctor

See a doctor urgently if:

• You see blood or dark slime in your stool
• You feel dizzy, light-headed, or can't keep any drinks down
• Your tummy pain is getting worse rather than easing
• You or your child has signs of dehydration such as a dry mouth, dark urine, or feeling very weak
• You have recently travelled to a region with poor sanitation and now have diarrhoea
• Your child is unsettled, drinking poorly or having far fewer wet nappies

Book a routine appointment if:

• Diarrhoea that has lasted more than a few days or keeps coming back
• Loose stools with bloating, wind or weight loss
• You would like advice on whether you need to be tested
• You are unsure whether you should be checked because of travel or a family member's illness

Diagnosis

Your doctor will start by asking about your symptoms, recent travel, what you have been eating and drinking, and whether anyone close to you has been unwell. Because the parasite can be invisible without a test, the key step is usually a stool sample. Knowing the exact cause matters, because an ordinary stomach bug and amoebiasis need different treatment. If there is a concern about complications or a liver abscess, the doctor may organise a blood test and a scan.

Tests that may be done

• Stool (poo) test: a sample goes to the laboratory to look for the parasite, parasite eggs or cysts. You may be asked for more than one sample on different days, as the parasite can be missed in a single sample.
• A newer stool test that detects tiny pieces of the parasite (an antigen test or PCR test), which is often more reliable than looking down a microscope
• Blood tests to check for anaemia, inflammation, or signs of infection elsewhere in the body
• An ultrasound scan or other imaging if the doctor suspects a collection of infection in the liver
• Occasionally a telescope examination of the bowel, done by a specialist, if the diagnosis is still unclear

What to expect at your appointment

Collecting a sample is simple and private: you put a small amount of stool into a pot and hand it in. Results usually come back within a few days to a couple of weeks depending on the test. Your doctor will contact you with the result and explain what it means. If the first sample is negative but symptoms continue, they may ask for more samples — this does not mean anything has gone wrong.

Treatment

Treatment has two aims: replacing the fluid and salts lost through diarrhoea, and clearing the parasite itself. Anyone with symptoms should be assessed by a healthcare professional, because the right treatment depends on the test result, your symptoms and your general health.

Self-care at home

• Drink small, frequent sips of an oral rehydration solution, available cheaply from pharmacies without a prescription — it replaces both water and salts better than water alone
• Keep eating simple food if you feel like it; you do not need to starve yourself, though light meals may be easier on your tummy
• Rest, and stay home from work, school or nursery until a healthcare professional says it is safe to return
• Wash your hands with soap and water after using the toilet and before preparing or eating food — this protects the people around you
• Keep drinking, even if you have some diarrhoea; the aim is to replace what you lose
• Avoid alcohol and very sugary drinks, which can make diarrhoea worse
• Do not swim or share towels until you are told it is clear, if your doctor advises against it

Medical treatments

Because a parasite causes the infection, treatment usually involves a course of medicine that kills it, prescribed by a healthcare professional after a positive test or a clear clinical picture. Some people need more than one type of medicine: one to fight the parasite in the bowel wall and settle symptoms, and a second, gentler course to clear any remaining forms of the parasite from the bowel so that you do not pass it on. Some medicines are not suitable for pregnancy, for very young children, or for people with certain other conditions, so it is important to tell your doctor about any other illness, pregnancy, or medicines you take. Dehydration is treated at the same time with fluids; if you are very dehydrated or unable to drink, fluids may be given through a drip in hospital. Never take leftover medicines or someone else's medicine, and always finish a course as your doctor explains.

When is surgery considered?

Surgery is rarely needed. It may be considered if a pocket of infection in the liver does not settle with medicine and needs draining, or in the uncommon case of a hole forming in the bowel wall, which requires emergency repair.

Living with this condition

While you are recovering, plan your days gently. Keep a bottle of rehydration drink nearby, know where the nearest toilet is, and give yourself permission to rest. It can take a week or two before your digestion feels fully normal again, and mild tiredness during that time is common. If you live with others, be extra careful with handwashing, separate towels, and cleaning the toilet and bathroom regularly.

Lifestyle tips

• Wash your hands with soap and water after the toilet, after changing nappies and before cooking or eating
• Keep your nails short and clean, especially if you have young children
• Clean toilet seats, handles and bathroom surfaces regularly while anyone in the house is unwell
• Avoid preparing food for other people until a healthcare professional says it is safe
• If you are travelling, drink bottled or boiled water and skip ice and unpeeled raw fruit in high-risk areas
• Tell any healthcare professional you see — including a pharmacist — that you have had a parasite infection, so your history is complete

Diet and exercise

There is no special 'amoebiasis diet', but a few sensible choices help. Sip fluids steadily through the day. Plain foods such as rice, noodles, bread, potatoes and cooked vegetables are often easier to tolerate than rich, spicy or very fatty meals. Some people find dairy, coffee or alcohol upset their tummy for a while, so try cutting back and see if it helps. Once you feel ready, gentle activity such as short walks can lift your mood and help your appetite return. Build up slowly and do not push yourself if you feel washed out.

Mental health and emotional wellbeing

Diarrhoea and tummy trouble can be quietly stressful. You may worry about needing a toilet urgently, about passing the infection to your family, or about a test result. Feeling anxious, embarrassed or low is common and understandable, and it usually eases once you have a diagnosis and a plan. Talk to someone you trust, and mention your worries to your doctor — they can answer questions you may be turning over in your head. If your low mood or anxiety is lasting or overwhelming, please reach out for crisis or mental health support in your country, or speak to your doctor or a local health service straight away.

Prevention

Yes, largely. The parasite spreads through contaminated food, water and hands, so good hygiene and safe water go a long way. Wash your hands with soap and water after the toilet and before eating or preparing food, and teach children to do the same. If you are in an area where the tap water may not be safe, drink bottled or boiled water, avoid ice, and peel your own fruit. Wash fruit and vegetables in safe water. Keep food covered against flies. Where sanitation is poor, use toilets or latrines and keep them clean. If someone in your household is diagnosed, a doctor may suggest testing or treating others who live with them, as the infection can pass between people.

Vaccines

There is currently no vaccine to prevent amoebiasis, so hygiene and safe food and water are the main protection.

Screening programmes

There is no routine screening programme for amoebiasis in the general population. Testing is offered when someone has symptoms, has been in contact with an infected person, or has travelled to a high-risk area and become unwell.

Complications

If left untreated

• Serious dehydration, which is especially risky for babies, young children and older adults
• A liver abscess — a collection of infection in the liver that causes fever and pain under the ribs on the right side
• A long-running infection that causes ongoing diarrhoea, weight loss and tiredness
• Anaemia (low iron in the blood) from losing blood in the stool
• A severe form of bowel inflammation that can, in rare cases, make a hole in the bowel
• In rare cases the infection can spread to other organs, such as the lungs or the brain
• Passing the infection on to other people without realising it

Long-term outlook

The outlook is good. When amoebiasis is found and treated, most people feel better within days and are completely back to normal within a few weeks. Even the more serious complications, such as a liver abscess, usually respond well once they are treated. The main thing is not to ignore ongoing diarrhoea, blood in the stool, or a fever with tummy pain — getting checked early makes recovery simpler and safer.

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