Every summer, a small but steady number of UK travellers return from holidays abroad with an unwelcome souvenir: a parasitic infection that can leave them dealing with unpleasant gastrointestinal symptoms for weeks. This summer we’ve seen a sharp rise in illness caused by cyclospora.
What is cyclospora?
Cyclospora is a microscopic parasite that causes an illness called cyclosporiasis. It doesn't occur naturally in the UK, but is found in a number of tropical and subtropical countries, including parts of Central and South America, South and Southeast Asia, the Middle East and Africa. For UK travellers, most cases in recent years have been linked to visits to Mexico.
The parasite spreads through food or water contaminated with infected human poo. It's most commonly associated with fresh produce, particularly soft or unpeeled fruit, salad leaves, and herbs such as coriander or basil, though contaminated water can also be a source. Cyclospora is not passed from person to person through everyday contact, so you won’t catch it from someone who is unwell.
What are the symptoms?
Symptoms typically appear around a week after eating or drinking something contaminated. They can include watery diarrhoea, stomach cramps, bloating, wind, nausea, fever, tiredness, muscle aches, and loss of appetite or weight.
For most people, the illness is unpleasant but self-limiting, resolving on its own within a few days to a few weeks. However, symptoms can sometimes persist for longer, or return after apparently clearing up. People with weakened immune systems, including those living with HIV, are at greater risk of more severe or prolonged illness. Diagnosis is confirmed through a stool sample test, and while most people recover without treatment, antibiotics can be prescribed for severe or lingering cases.
What should I do before I go?
Being prepared can help you avoid illness or cope with symptoms better:
- ahead of travelling, you can visit NaTHNaC's TravelHealthPro website to check country-specific travel health information
- pack a basic first aid kit, including hand sanitiser and oral rehydration sachets in case you develop diarrhoea
- make sure you have comprehensive travel insurance
How can I reduce my risk while travelling?
There's no vaccine against cyclospora so prevention comes down to good food and water hygiene, whether you're backpacking or staying in a 5-star all-inclusive resort. Useful precautions include:
- washing your hands regularly with soap and clean water, using alcohol hand gel only when handwashing isn't available
- drinking only bottled or boiled water where the tap water isn't safe, including for brushing your teeth
- avoiding ice in drinks
- avoiding fresh produce that may not have been washed in safe water, such as berries, salads and herbs
- choosing fruit you can peel yourself, like bananas or oranges
- opting for pasteurised dairy products
- eating freshly cooked food served hot
- being cautious with smoothies and juices, which may contain raw fruit or vegetables
What should I do if I fall ill while abroad?
If you do develop gastrointestinal symptoms while abroad, staying hydrated with safe fluids (bottled water and hot drinks made with freshly boiled water) and oral rehydration solutions is important, and you should seek medical advice promptly if you have a weakened immune system or your symptoms are severe. If you have symptoms when you return, you should get medical help and mention your recent travel, including everywhere you visited. This helps healthcare professionals consider the right possible causes and arrange appropriate testing.
What is UKHSA's role in this area?
The UK Health Security Agency (UKHSA) is responsible for protecting the public from infectious diseases, including gastrointestinal infections like cyclosporiasis. This work includes monitoring disease trends, investigating outbreaks, and issuing public health advice.
UKHSA does not carry out routine, ongoing surveillance of cyclosporiasis as it does for some pathogens. Instead, laboratory-confirmed cases are reported to UKHSA through the national laboratory notification system, and the agency publishes findings and advice when it identifies a rise in cases, such as during a notable outbreak. When this happens, UKHSA may work with partner organisations, including the National Travel Health Network and Centre (NaTHNaC), ABTA, and public health authorities in affected countries, to investigate clusters and ensure travellers have access to up-to-date guidance.
This is part of UKHSA's broader responsibility for health protection: tracking a wide range of infectious diseases, spotting unusual patterns or increases, and translating that surveillance into practical, timely advice for the public and for healthcare professionals.
Cyclospora is a good reminder that even in comfortable holiday settings, food and water hygiene matters. Simple precautions, drinking safe water, choosing well-cooked food, and being cautious with unpeeled produce help to reduce your risk. If you do become unwell after travelling, don't hesitate to seek medical advice and mention your travel history.