Health officials have issued fresh warnings about giardiasis, a parasitic stomach bug that can cause prolonged diarrhoea, cramps, and bloating, as new data from the UK Health Security Agency (UKHSA) reveals infections in England reached their highest level in nearly a decade. The agency recorded 6,069 laboratory-confirmed cases in 2025, an 11.4% increase from the previous year and the highest annual total since 2016.
UKHSA investigates spike in giardiasis infections
The UKHSA is investigating the reasons behind the surge, which peaked between September and November. The agency said more effective testing, increased travel following the pandemic, and climate change were likely contributing factors. While the illness can be contracted within the UK, a number of cases were reported in people returning from Asia, Africa, and South America.
To reduce risk, travellers are urged to drink bottled water, stick to cooked food in affected regions, and be cautious when swimming in rivers, lakes, or the sea. Nicola Love, senior food safety surveillance lead at UKHSA, stressed the importance of awareness and precaution across the board, since giardiasis can cause serious complications, especially in young children, the elderly, and those with weakened immune systems.
Symptoms and spread of the parasitic infection
According to the NHS, symptoms of giardiasis include smelly diarrhoea, stomach pain or cramps, flatulence, smelly burps that may smell like eggs, bloating, and weight loss. Daniel Turnbull, professional standards pharmacist at Pharmacy2U, told Metro: 'The infection itself can last around a week, however there are some cases where symptoms have persisted for several weeks and even months. This is an important reminder to why ongoing diarrhoea should not be ignored.'
Hanna Yusuf, prescribing pharmacist at Chemist4U, explained that giardiasis is transmitted 'primarily through contact with infected people or animals, as well as ingesting contaminated food, water and drinks.' She also warned that the infection can be contracted through sexual contact, noting that the NHS website says this is especially common during unprotected anal and oral sex.
Daniel added: 'Giardiasis can be easily spread, particularly as some people can carry the infection without showing symptoms. When someone has contracted giardiasis, they are most infectious from the onset of symptoms, if any present, until around two days after they have stopped.'
Treatment and prevention advice
If giardiasis is suspected, individuals should visit their GP, who will likely arrange a stool sample to confirm the infection. Daniel explained that treatment 'is usually in the form of antibiotics to treat the infection, alongside plenty of fluids to reduce the risk of dehydration.' Hanna highlighted that dehydration is 'one of the biggest concerns with the infection,' and that 'drinking plenty of fluids is so important, alongside adding oral rehydration sachets or solutions to replace electrolytes you may have lost through vomiting and diarrhoea.'
While giardiasis is unpleasant, Daniel said it is 'unpleasant rather than dangerous in most healthy individuals.' He advised: 'The best protection from giardia and giardiasis is good hand hygiene: washing your hands thoroughly with soap and water after using the toilet or changing nappies and before preparing food and drink. If you are suffering from a giardiasis infection, avoid swimming until two weeks after your diarrhoea has stopped and avoid preparing food for other people whilst you are infectious.'
