Key Summary
- Giardia infection can spread through direct contact with infected people or animals, or by swallowing contaminated food or water.
- The infection can be acquired in the UK as well as during international travel.
- The treatment includes maintaining hydration and antibiotics.
A new data by the UK Health Security Agency (UKHSA) shows a rise in cases of Giardia, a gastrointestinal illness caused by a parasite Giardia intestinalis, across the country.
The most common symptom is diarrhoea, which is often accompanied by abdominal cramps, bloating, burping, wind and weight loss.
The treatment includes maintaining hydration (drinking plenty of water) and antibiotics.
If left untreated, in rare cases, children can experience significant weight loss, malnutrition and stunted growth.
The number of giardiasis cases in England rose from 5,450 in 2024 to 6,069 in 2025, and this is the highest number of cases reported since 2016.
The number of laboratory-confirmed cases reported each year returned to pre-pandemic levels in 2023 and has risen since.
London accounted for nearly a quarter of cases (1,568), following by North West (1,029).
Cases peaked in autumn, with the highest number of reports in October (599 cases), followed by September (580 cases) and November (574 cases).
Main causes
UKHSA is investigating the reasons for rise in cases, but it is possibly due to a mix of factors, including new and more effective testing, increased travel since the pandemic and climate and environmental changes.
Giardia infection can be acquired in the UK as well as during international travel.
It spreads through direct contact with infected people or animals, or by swallowing contaminated food or water. The infection can also be sexually transmitted.
Infections are also seen in returning travellers from Southern Asia, South-Eastern Asia, Africa and South America.
Precautions to be taken
International travellers should take precautions when travelling abroad, including drinking bottled water and consuming cooked food, rather than raw items such as salad vegetables washed in tap water.
Travellers should be careful when swimming in rivers, lakes, the sea, where water may be contaminated.
Nicola Love, Senior Food Safety Surveillance Lead at UKHSA, said: "There are some simple precautions everyone can take to reduce their risk, whether you are planning an autumn getaway somewhere warm or staying in the UK.
"Good hygiene can help prevent giardiasis and other common gastro illnesses. Wash your hands with soap and water after using the toilet, after changing nappies, and before preparing food. Encourage children to wash their hands regularly too.
"If you have a Giardia infection, continue to hydrate yourself and see your GP, do not go swimming until 2 weeks after your diarrhoea has stopped. Parents should contact their GP or NHS 111 if they or their children are ill with dehydration, or if diarrhoea worsens or lasts longer than 3 days."
