Health officials have issued fresh giardiasis warnings this week amid surging rates of the parasitic stomach bug that can cause diarrhoea, cramps and bloating for months on end. The UK Health Security Agency (UKHSA) recorded 6,069 laboratory-confirmed infections in England in 2025 — up 11.4% on the previous year, marking the highest number of annual cases since 2016.
Investigation into the spike
The agency is investigating what’s behind the spike, which peaked between September and November, but said more effective testing, increased travel since the pandemic, and climate change were likely potential reasons. While the gastrointestinal illness — caused by a parasite called giardia intestinalis — can be picked up here, a number of cases were seen in people returning from Asia, Africa and South America.
To reduce their risk, travellers were urged to drink bottled water and stick to cooked food in affected regions, and to be careful when swimming in rivers, lakes, and the sea. But 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
According to the NHS, symptoms of the condition include smelly diarrhoea, stomach pain or cramps, flatulence, smelly burps – which may smell like eggs – bloating, and weight loss. “The infection itself can last around a week, however there are some cases where symptoms have persisted for several weeks and even months,” Daniel Turnbull, professional standards pharmacist at Pharmacy2U, told Metro. “This is an important reminder to why ongoing diarrhoea should not be ignored.”
As Hanna Yusuf, prescribing pharmacist at Chemist4U, explains, giardiasis is transmitted “primarily through contact with infected people or animals, as well as ingesting contaminated food, water and drinks.” She warns you can also contract the infection “by having sex with someone who has it” — which the NHS website says is especially common during unprotected anal and oral sex.
Daniel adds: “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
If you suspect you may have giardiasis, you should visit your GP, who will likely arrange a stool sample to confirm infection. After this, Daniel explains treatment “is usually in the form of antibiotics to treat the infection, alongside plenty of fluids to reduce the risk of dehydration.” In Hanna’s view, this is “one of the biggest concerns with the infection,” and why “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.”
Although you certainly don’t want to catch it, and should be extra careful around younger children, older adults and those with a weakened immune system, Daniel says it’s “unpleasant rather than dangerous in most healthy individuals.” He continues: “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.”
