15238 Giardiasis

Overview

Giardiasis is an infection of the gut caused by a tiny parasite called Giardia. It can cause diarrhoea, stomach cramps, and make you feel very tired. You usually pick it up from contaminated water or food.

Yes, giardiasis is one of the most common gut parasites worldwide. It is especially common in areas with poor sanitation, but it can also occur in settings like campsites, nurseries, and even swimming pools.

Anyone can get giardiasis, but it is more likely to affect children under 5, people who travel to developing countries, campers and hikers who drink untreated water, and people with a weakened immune system.

Symptoms

Common symptoms

• Watery or foul-smelling diarrhoea
• Stomach cramps and bloating
• Excess gas (often smelly)
• Nausea
• Fatigue and generally feeling unwell
• Loss of appetite and weight loss

Symptoms in children

• Diarrhoea lasting more than a few days
• Poor weight gain or weight loss
• Tiredness and irritability
• Tummy pain and bloating

Symptoms in older adults

• Milder but longer-lasting diarrhoea
• Higher risk of dehydration
• Often combined with other health conditions, making recovery slower

Causes

Main causes

• Swallowing water from lakes, rivers, or streams that contains the Giardia parasite
• Drinking or using untreated municipal water in some countries
• Eating raw or undercooked food washed in contaminated water, or handled by an infected person
• Touching your mouth after contact with infected faeces (poo) – for example, during a nappy change or from farm animal contact

Risk factors

• Travelling to regions with poor water treatment and sanitation
• Camping, hiking, or staying in places with untreated water
• Working in or attending childcare settings or nurseries
• Having contact with farm animals or domestic pets that carry Giardia
• Having a weakened immune system due to illness or medication

When to see a doctor

See a doctor urgently if:

• Diarrhoea that is severe or contains blood
• Signs of dehydration, especially in a child or older person
• Not being able to keep fluids down
• High temperature or severe tummy pain

Book a routine appointment if:

• Diarrhoea that lasts more than a few days
• Recurring stomach cramps after a possible exposure
• You have recently travelled and are not improving
• Need advice about work, school, or swimming restrictions

Diagnosis

Your doctor will ask about your symptoms, travel history, and any possible contact with contaminated water or food. They may then ask for a stool (poo) sample.

Tests that may be done

• Stool sample – the main test to find Giardia parasites under a microscope
• Sometimes more than one stool sample is needed over a few days
• If the infection is hard to find, your doctor may arrange a blood test or an endoscopy (a small tube with a camera to look inside your gut)

What to expect at your appointment

Collect the stool sample as directed by your doctor or local clinic. Results usually take a few days. If the test is positive, your doctor will discuss treatment and hygiene steps to prevent spread to others.

Treatment

Treatment focuses on clearing the parasite and preventing dehydration. Many people are treated with medication, but even without medication the infection sometimes clears by itself. Your doctor will decide based on your symptoms, age, and general health.

Self-care at home

• Drink plenty of fluids – sips of water, or a pharmacy-bought oral rehydration solution if needed
• Rest, and do not go to work, school, or nursery until you have had no diarrhoea for 24 to 48 hours
• Wash your hands thoroughly with soap and water after the toilet and before touching food
• Do not prepare food for others until symptoms have stopped
• Avoid swimming pools, hot tubs, and lakes until fully recovered

Medical treatments

A doctor may prescribe an anti-parasite medicine to kill the Giardia parasite. The drug and duration will depend on your age, pregnancy or other health conditions. It is important to take the full course even if you feel better. Some people need a repeat course if the parasite persists. Always follow your doctor’s advice.

Living with this condition

While you recover, it’s important to keep up your fluid intake and eat gentle, easy-to-digest foods. Most people feel noticeably better within 1–2 weeks, but tiredness can linger a little longer.

Lifestyle tips

• Keep hands clean and avoid sharing towels or flannels
• Stay away from work, school, or nursery until you are cleared to return
• Wash fruits and vegetables carefully, and drink safe water
• Delay travelling to areas with poor sanitation until you are fully recovered

Diet and exercise

Stick to plain foods such as rice, bananas, toast and boiled potatoes. Avoid dairy products, greasy, spicy or very sugary foods for a few weeks. Gentle exercise like walking is fine when you feel up to it, but stop if you feel dizzy.

Mental health and emotional wellbeing

Having persistent diarrhoea can be exhausting and embarrassing. It’s normal to feel low, anxious, or fed up. Talk to your doctor if you are struggling, and remember that this infection does not define you – most people recover with simple steps.

Prevention

Yes. The key is good hygiene and safe water habits. Wash hands frequently, especially after the toilet, before eating, and after touching animals. When travelling or camping, boil water or use water purifying tablets, and avoid ice or raw food that may be washed in unsafe water.

Vaccines

There is currently no vaccine to prevent giardiasis.

Screening programmes

Routine screening is not needed for the general public. But if you are in a high-risk group (for example, a family member of an infected person), your doctor may suggest testing.

Complications

If left untreated

• Prolonged diarrhoea leading to dehydration, especially in children and older adults
• Poor absorption of nutrients (malabsorption), causing weight loss and low body weight
• Temporary lactose intolerance – difficulty digesting dairy products for a few weeks
• Longer-term fatigue or joint aches in some people

Long-term outlook

The outlook is very good. With proper treatment, most people recover completely within a few weeks. Even without treatment, it often clears on its own, but it can take longer. Rare long-term problems are uncommon, and your doctor can help you manage any lingering symptoms.

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