Giardiasis Cases Rise in the UK: What Travellers Need to Know About Symptoms, Prevention and Treatment

Giardiasis cases in the UK have increased, prompting travel health advice. Learn about Giardia symptoms, causes, prevention, treatment and when to seek medical help.

A parasitic stomach infection is attracting renewed attention in the UK after health officials reported a significant increase in cases. Known as giardiasis, the infection can cause persistent diarrhoea, bloating, stomach cramps and other digestive problems, and travellers may be particularly vulnerable when visiting areas where food and water safety standards differ.

According to figures from the UK Health Security Agency (UKHSA), 6,069 cases of giardiasis were reported in the UK during 2025. That represents an increase from 5,450 cases recorded in 2024 and the highest annual total reported since 2016.

The rise has prompted renewed advice for people travelling abroad, particularly those visiting parts of Southern Asia, South-Eastern Asia, Africa and South America.

What is giardiasis?

Giardiasis is an intestinal infection caused by a microscopic parasite called Giardia. The parasite can infect the digestive system after a person accidentally swallows it.

Giardia can be present in contaminated drinking water, food and recreational water. Infection can also spread through close contact with an infected person or animal.

Although giardiasis can occur in the UK, international travel can increase exposure to contaminated water and food. Travellers may encounter risks when drinking untreated water, eating raw foods washed with contaminated water or swimming in potentially contaminated water.

The infection is not necessarily limited to remote destinations. Giardia can also be found in streams, lakes, wells, swimming pools and other water sources.

Why are giardiasis cases increasing?

The UKHSA reported an 11.4 per cent annual increase in cases between 2024 and 2025.

Health officials have suggested several possible explanations for the increase. These include the return of international travel following the pandemic, changes associated with climate conditions and improvements in testing and diagnosis.

However, an increase in reported infections does not necessarily mean that every case was acquired overseas. Giardiasis can be contracted within the UK as well as abroad.

The important message for travellers is that basic food, water and hygiene precautions can help reduce the risk.

What are the symptoms of giardiasis?

Symptoms can vary from person to person. Some people infected with Giardia may have no noticeable symptoms, while others can develop uncomfortable and prolonged digestive problems.

Common symptoms include:

• Diarrhoea, which can sometimes be particularly unpleasant or foul-smelling
• Stomach pain and cramps
• Bloating
• Excessive wind
• Smelly burps
• Nausea
• Tiredness
• Weight loss

One of the concerns with giardiasis is that symptoms may not disappear quickly. According to NHS guidance, the infection can sometimes continue for several weeks or longer.

Persistent diarrhoea can also lead to dehydration. This can be particularly concerning for young children, older adults and people with weakened immune systems.

In children, prolonged untreated infection can potentially contribute to nutritional problems and affect growth.

How does Giardia spread?

Giardia is primarily spread when microscopic parasites are swallowed.

Contaminated water is an important source of infection. This can include untreated drinking water as well as water in lakes, rivers and other recreational environments.

Food can also become contaminated. Eating raw foods that have been washed with unsafe water may create a risk, particularly in destinations where tap water is not considered safe to drink.

The infection can also spread through direct contact with an infected person or animal.

Because of this, hand hygiene is an important part of prevention. Washing hands thoroughly with soap and water after using the toilet, changing nappies and before preparing or eating food can help reduce transmission.

How can travellers reduce their risk?

Travellers can take several practical precautions to lower their chances of contracting giardiasis.

When visiting destinations where water safety is uncertain, consider drinking bottled water from a sealed container. Water that has been appropriately treated can also be used where suitable.

Be cautious with raw foods, particularly salads and uncooked vegetables that may have been washed using unsafe water.

Food that has been thoroughly cooked and served hot is generally a safer choice in situations where food hygiene is uncertain.

Travellers should also think carefully before swimming in rivers, lakes and other natural bodies of water abroad. Avoid swallowing recreational water, as even apparently clean water can contain microorganisms.

Good hand hygiene remains important throughout a trip, especially after using the toilet and before handling food.

What should you do if you develop symptoms after travelling?

Developing diarrhoea after returning from a holiday does not automatically mean that you have giardiasis. A number of infections and other conditions can cause similar symptoms.

However, persistent diarrhoea, significant bloating, unexplained weight loss or continuing stomach problems after travel should not be ignored.

People experiencing concerning symptoms should contact a GP or seek appropriate medical advice. A healthcare professional may recommend testing to determine whether Giardia or another infection is responsible.

Treatment can involve prescription medication, including a course of antibiotics or other anti-parasitic medicines depending on the circumstances.

Keeping hydrated is particularly important when experiencing diarrhoea. People should seek urgent medical advice if they develop signs of significant dehydration or become seriously unwell.

What if you have giardiasis?

Anyone diagnosed with giardiasis should follow medical advice and take steps to avoid passing the infection to others.

Because the parasite can spread through contact with infected faecal matter, careful handwashing is essential.

The UKHSA also advises people with giardiasis to avoid swimming until two weeks after their diarrhoea has stopped. This can help reduce the risk of contaminating recreational water and exposing other people.

Parents and carers should pay particular attention to children with diarrhoea because dehydration can develop more quickly in young children.

The UKHSA advises contacting a GP or NHS 111 if a child or adult is experiencing dehydration, if diarrhoea becomes worse or if it lasts for more than three days.

The key takeaway for UK travellers

The rise in reported giardiasis cases is a reminder that stomach infections remain a potential travel health concern. Giardia can be contracted both overseas and in the UK, but travellers can reduce their risk by taking sensible precautions with drinking water, food, swimming and personal hygiene.

For most people, giardiasis is treatable. However, symptoms can sometimes persist and complications can be more serious for vulnerable groups.

If you develop prolonged diarrhoea, bloating, stomach cramps or unexplained weight loss after travelling, speak with a healthcare professional rather than assuming the symptoms will disappear on their own.

Sources

• UK Health Security Agency (UKHSA): Reported 2025 giardiasis figures and travel-related health advice.
• NHS: Information on giardiasis symptoms, transmission and treatment.
• The Independent, published 26 August 2026.

Disclaimer

This article is for general information and educational purposes only. It is not medical advice and should not be used to diagnose or treat giardiasis or any other illness. Symptoms can have many different causes. If you are concerned about persistent diarrhoea, dehydration, severe abdominal symptoms or illness following travel, contact a GP, NHS 111 or another qualified healthcare professional. In an emergency, seek urgent medical assistance.