Cyclosporiasis Cases Rise Among UK Travellers Returning From Mexico

A rise in cyclosporiasis among UK travellers has prompted fresh health advice as officials investigate infections linked mainly to holidays in Mexico’s Riviera Maya and Cancún regions.

UK health authorities have reported 67 cases of cyclosporiasis between 30 April and 15 July 2026, including 30 in England, 27 in Scotland and 10 in Wales.

Travel information was available for 52 patients. Of those, 48, about 92%, had visited Mexico, including one person who had also travelled to the United States. One other patient reported visiting only the US and another had travelled to Kenya.

The 67 infections recorded in approximately 11 weeks are equivalent to about 72% of the average annual total of 93 cases reported between 2022 and 2025.

The comparison does not amount to a full-year forecast, but it explains why the UK Health Security Agency has described the increase as sharp and expects the number to continue rising during the summer holiday season. The highest recent annual total was 359 cases in 2016.

Detailed information has so far been collected for 28 Mexico-linked patients. Most reported travelling to the Riviera Maya, while several stayed in Cancún.

They used different hotels and consumed a range of food and drink through all-inclusive packages, meaning the published investigation has not identified one resort or single food item responsible. Data collection remains under way.

Dr Philip Veal, a consultant in travel health at UKHSA, said: “We have recently detected a rise in Cyclospora infections among travellers returning from Mexico.”

The agency is working with ABTA and Mexican public health authorities to investigate the clusters. It is also monitoring the potential for infections associated with travel to the US, where a widespread outbreak has been reported.

What Is Cyclosporiasis?

Cyclosporiasis is an intestinal illness caused by the microscopic Cyclospora parasite. It does not occur naturally in the UK and is usually acquired by consuming food or water contaminated with infected human faeces.

Fresh produce can be a source, particularly salad leaves, herbs such as coriander and basil, berries and fruit that has not been peeled. The infection is not passed between people through ordinary contact.

Symptoms normally begin about a week after contaminated food or drink is consumed. They can include frequent watery diarrhoea, stomach cramps, bloating, nausea, tiredness, fever, wind, muscle aches, reduced appetite and weight loss.

Most patients recover without treatment within days or weeks, although symptoms may persist or return after appearing to clear. People with weakened immune systems face a greater risk of prolonged or more serious illness. Doctors can confirm an infection using a stool sample, while antibiotics may be prescribed for severe or continuing cases.

Advice For London Travellers

UKHSA’s published figures provide a total for England but do not include a London-specific case count or identify a cluster in the capital. Its warning nevertheless applies to London residents preparing to visit Mexico and those who have recently returned.

There is no vaccine against Cyclospora. Travellers are advised to drink bottled or boiled water where tap water may be unsafe, including when brushing their teeth, and to avoid ice.

Officials also recommend choosing freshly cooked food served hot, peeling fruit personally and avoiding salads, berries and herbs that may have been washed in unsafe water. Smoothies and juices can also contain uncooked produce.

Anyone who becomes unwell abroad should remain hydrated and seek prompt advice if symptoms are severe or they have a weakened immune system. Returning travellers experiencing gastrointestinal symptoms should contact a health professional and disclose every country and resort they visited so appropriate testing can be arranged.

The investigation remains active, with UKHSA expecting additional travel-associated cases as summer journeys to Mexico and the US continue. Its current response centres on food and water precautions, continued surveillance and cooperation with travel organisations and Mexican authorities.