Cases of giardiasis, a parasitic stomach bug causing diarrhoea, bloating, burping, wind and weight loss, have risen by 11.4 per cent year-on-year in England, according to data from the UK Health Security Agency (UKHSA). The agency recorded 6,069 cases in 2025, the highest since 2016 and up from 5,450 the previous year.
Regional and seasonal trends
London reported the highest number of cases with 1,568, followed by the north west with 1,029. Cases peaked in autumn, with the highest number of reports in October (599 cases), followed by September (580) and November (574).
Giardia infection can be picked up in the UK as well as overseas, and is spread by consuming contaminated food or water, or through direct contact with infected people or animals. It can also be sexually transmitted. In rare untreated cases, children with the infection can suffer malnutrition and stunted growth.
Possible causes and official advice
Health officials said the 11.4 per cent annual rise may be linked to increased travel since the pandemic, climate change, or better testing. According to the UKHSA, infections are being seen in people returning from Southern Asia, South-Eastern Asia, Africa and South America.
Nicola Love, senior food safety surveillance lead at UKHSA, said: “We are seeing a rise in giardiasis in the UK. Symptoms can last from weeks to several months and if left untreated, it can cause serious complications especially in young children, the elderly and those with weakened immune systems.”
Travel precautions and hygiene tips
Those travelling should drink bottled water and eat cooked food rather than raw items, such as salads that have been washed in tap water. The UKHSA also advised people to avoid swimming in rivers, lakes or the sea when abroad.
Ms Love added: “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.”
She advised washing hands with soap and water after using the toilet, after changing nappies, and before preparing food, and encouraging children to wash their hands regularly. Those with a giardia infection should continue to hydrate and see their GP, and should not go swimming until two weeks after 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 three days.
