Giardia Cases In England Hit Highest Level

Why are Giardia cases rising in England? Here’s what the latest data and research reveal about symptoms, transmission, treatment and prevention.

Cases of giardiasis, a parasitic gastrointestinal infection, have reached their highest level in England since 2016, according to new data from the UK Health Security Agency (UKHSA). ()

England recorded 6,069 laboratory-confirmed cases in 2025, up from 5,450 in 2024. That represents an 11.4% increase, or 619 additional cases, and the highest annual total reported since 2016. London recorded the most cases at 1,568, followed by the North West with 1,029.

What is Giardiasis?

Giardiasis is a gastrointestinal infection caused by the parasite Giardia intestinalis. It commonly affects the digestive system and can cause diarrhea, abdominal cramps, bloating, burping, excessive wind and weight loss. While many infections resolve, symptoms can sometimes continue for weeks or several months.

In rare cases, prolonged or untreated infection can lead to serious complications, particularly among young children, older adults and people with weakened immune systems. Children may experience significant weight loss, malnutrition and impaired growth.

Why Are Giardia Cases Increasing?

UKHSA said it is investigating the reasons behind the rise. Several factors may be contributing, including more effective diagnostic testing, increased international travel following the pandemic, and climate and environmental changes. Laboratory-confirmed cases returned to pre-pandemic levels in 2023 and have continued to increase since then.

Giardia can be acquired in England as well as during international travel. It spreads through direct contact with infected people or animals and by swallowing contaminated food or water. It can also be sexually transmitted. UKHSA has reported infections among travelers returning from Southern Asia, South-Eastern Asia, Africa and South America.

Research Links Giardiasis To International Travel

The travel connection is also supported by research. A study of gastrointestinal infections among UK international travelers examined factors associated with acquiring these infections during overseas trips, highlighting travel destinations and exposure to different food, water and sanitation conditions as important considerations. ()

What Are The Symptoms Of Giardiasis?

Common symptoms include:

• Diarrhea, which can be persistent
• Abdominal cramps or stomach pain
• Bloating
• Excessive gas or wind
• Burping
• Weight loss

Some people may have no symptoms, while others can experience digestive problems for weeks or months. The UKHSA says cases in England peaked during autumn 2025, with 599 reports in October, 580 in September and 574 in November.

Can Giardiasis Become Difficult To Treat?

Most cases can be managed with appropriate treatment and hydration, but researchers are also investigating infections that do not respond to standard treatment.

A 2026 study from researchers in London examined 531 Giardia cases seen at the Hospital for Tropical Diseases between 2020 and 2024, focusing on nitroimidazole-refractory giardiasis, in which the infection does not respond to commonly used first-line drugs. This research adds another dimension to the current rise in cases, showing that while giardiasis is often treatable, some infections can prove more challenging to manage. ()

How Does Giardia Spread?

People can become infected by swallowing Giardia cysts through contaminated food or water. Transmission can also occur through close contact with an infected person or animal. Travel can increase exposure to contaminated water and food. UKHSA recommends that travelers take precautions, including drinking bottled water and choosing cooked food rather than raw foods such as salad vegetables washed in potentially contaminated tap water. People should also take care around recreational water, including rivers, lakes and open-water swimming areas, where contamination may occur.

How Can You Prevent Giardiasis?

Good hygiene remains one of the simplest ways to reduce the risk. UKHSA recommends washing hands with soap and water after using the toilet, after changing nappies and before preparing food.

Travelers should also:

• Drink bottled or otherwise safe water
• Avoid raw food washed in potentially contaminated water
• Practice careful hand hygiene
• Take precautions when swimming in potentially contaminated water

Anyone diagnosed with Giardia should stay hydrated and seek medical advice. UKHSA advises people with an infection not to swim until two weeks after diarrhea has stopped. Parents should contact a GP or NHS 111 if they or their child develops dehydration, if diarrhea worsens or if it lasts for more than three days.

What Does The Rise In Giardia Cases Mean?

The increase to more than 6,000 reported cases in England highlights the continued importance of food and water safety, particularly for international travelers. Although improved testing may account for part of the increase, UKHSA is also examining the potential contribution of travel and environmental changes.

For people with persistent diarrhea, abdominal discomfort or unexplained weight loss, particularly following international travel or exposure to potentially contaminated water, giardiasis is one possible cause that may require medical assessment.

References:

1. Giardia cases in England reach highest level since 2016 – (https://www.gov.uk/government/news/giardia-cases-in-england-reach-highest-level-since-2016)
2. Risk factors associated with acquiring gastrointestinal infections in UK international travellers: a case-control study – (https://pubmed.ncbi.nlm.nih.gov/41566745/)
3. Epidemiology and management of nitroimidazole-refractory giardiasis – (https://pubmed.ncbi.nlm.nih.gov/41543148/)

Source-Medindia