Travel alert as parasite behind ‘explosive diarrhoea’ surges

Travellers heading to popular beach resorts this summer are being urged to review basic food and hygiene precautions as cases of cyclosporiasis, a parasitic infection widely described as causing “explosive diarrhoea,” climb in key holiday hotspots.

Sharp rise in cases linked to Mexico resort areas

Publicly available surveillance data from the United Kingdom and North America indicate a marked increase in confirmed cyclosporiasis cases since late spring, with many infections linked to recent travel to Mexico’s Caribbean coast. Reports describe clusters among holidaymakers returning from all-inclusive resorts in the Riviera Maya and Cancún areas, where visitors often share buffet dining and large pool complexes.

Cyclosporiasis is caused by the microscopic parasite Cyclospora cayetanensis, which infects the small intestine. It is typically contracted by consuming food or drink contaminated with microscopic oocysts shed in human faeces. The illness has a history of appearing in seasonal waves, often tied to fresh produce supply chains and peak travel periods, but this year’s jump has prompted renewed attention to risks in mass-market resort destinations.

Health coverage from the UK and US highlights that many affected travellers had stayed at a range of different hotels rather than a single property, and had eaten a wide variety of foods via all-inclusive packages. This pattern points to broader contamination issues in local food or water systems rather than a problem confined to one resort, and may complicate efforts to trace the precise source.

Officials in Mexico have previously worked with international partners during similar outbreaks, focusing on agricultural practices and water quality in areas supplying fresh herbs, salad greens and soft fruits to hotels and export markets. Current investigations are again centring on the safety of produce and food-handling practices along the tourism corridor.

What the ‘explosive diarrhoea’ parasite does to travellers

Cyclosporiasis typically begins several days to a week after exposure, a delay that means many holidaymakers do not fall ill until they are back home. The hallmark symptom is frequent, watery diarrhoea that can be sudden and forceful, leading to the widely used “explosive diarrhoea” description in media coverage and public-health advisories.

In addition to diarrhoea, infected travellers often report painful stomach cramps, bloating, nausea, loss of appetite, low-grade fever and profound fatigue. Without treatment, symptoms can come in waves and last for weeks, sometimes leading to significant weight loss and dehydration. In otherwise healthy people the illness is rarely life-threatening, but it can be debilitating and disruptive, particularly after long-haul flights or for those returning directly to work.

People with weakened immune systems, including older adults and those with chronic medical conditions, may face a higher risk of prolonged or more severe disease. Clinical guidance notes that cyclosporiasis can require prescription antibiotics rather than standard over-the-counter remedies used for routine travellers’ diarrhoea. Diagnosis typically relies on stool tests that specifically look for Cyclospora, which means cases can be missed if clinicians are not alerted to recent travel to affected areas.

Unlike some bacterial causes of food poisoning, this parasite does not usually spread directly from person to person in household or hotel settings, because the oocysts passed in faeces need time in the environment before becoming infectious. The main risk is therefore linked to contaminated water used in agriculture or food preparation, rather than casual contact with an ill fellow traveller.

Key hotspots and timing for heightened risk

The latest surveillance summaries point to Mexico’s Caribbean resort belt as a primary focus of concern, coinciding with the peak summer holiday season for visitors from the United Kingdom, United States and Canada. Many of the recent UK cases with travel information had stayed on the Riviera Maya or in Cancún, while US reports also reference infections among people returning from Mexican beach destinations.

Historically, cyclospora outbreaks involving travellers from North America and Europe have been detected most often between late spring and early autumn. This timing overlaps with increased consumption of fresh, uncooked produce such as salad mixes, coriander, basil and soft fruits, as well as heightened demand in tourist zones where thousands of meals are prepared daily for international guests.

Although Mexico’s Caribbean coast is currently drawing the most attention, cyclosporiasis is not confined to a single country. The parasite occurs in many tropical and subtropical regions, and sporadic cases linked to imported produce have been recorded in people who did not travel at all. For travellers, however, the combination of buffet-style resort dining, busy kitchens and reliance on complex food supply chains appears to create conditions in which contamination events can affect large numbers of guests.

Travel industry analysts note that there is no broad evacuation or no-go advisory for Mexico’s main resort areas related to the parasite. Instead, health agencies are focusing on targeted alerts, improved detection and practical advice for visitors, aiming to reduce risk without halting tourism to destinations that rely heavily on international arrivals.

Practical steps holidaymakers can take

Experts in travel medicine emphasise that cyclosporiasis is preventable, though no vaccine currently exists. The most important protection involves food and water choices. Travellers are advised to favour food that is thoroughly cooked and served hot, and to be cautious with raw items that may have been washed in untreated water, including salad greens, fresh herbs, unpeeled fruit and garnishes.

Where possible, visitors can choose fruit they peel themselves, such as bananas or oranges, and opt for bottled drinks with intact seals or beverages made from boiled water. Ice of uncertain origin is a potential risk, as are drinks mixed with tap water. In resort settings, it may be difficult to know the exact source of ingredients, but avoiding large amounts of raw salad and uncooked toppings during periods of heightened alerts can lower the chance of exposure.

Good hand hygiene remains another key measure. Regular handwashing with soap and safe water before eating, and after using the bathroom or changing nappies, helps reduce contact with faecal contamination. Alcohol-based hand sanitisers do not reliably inactivate Cyclospora on their own but can be a useful supplement when soap and water are not immediately available.

Travel health guidance also encourages people to seek medical advice if they develop persistent watery diarrhoea, stomach cramps or unexplained fatigue during or after a trip to an affected area, particularly if symptoms last more than a few days. Mentioning recent travel, resort stays and buffet dining can prompt clinicians to order specific tests for parasites rather than assuming a short-lived viral or bacterial infection.

What this means for upcoming summer travel

For many would-be holidaymakers, news of a parasite linked with severe diarrhoea in popular sun destinations is unsettling. Travel planners and health commentators stress, however, that the overall risk for any individual traveller remains relatively low, and that simple precautions can substantially reduce it. Most visitors to the affected regions will not become ill, and those who do generally recover fully with appropriate care.

At the same time, the current surge in cases illustrates how modern tourism and global food supply chains can amplify local hygiene problems into international health issues. Large, all-inclusive resorts that cater to thousands of guests each week depend on high volumes of fresh produce and prepared foods, meaning that a single point of contamination can affect people from multiple countries within a short period.

Publicly accessible outbreak updates suggest that monitoring activities are ongoing, with health agencies using laboratory data and interviews with patients to narrow down likely sources. Investigators are paying close attention to specific food items, distribution networks and common patterns among travellers, information that could later inform targeted recalls or stronger guidance for food producers and resort operators.

For now, prospective visitors to resort hotspots are being encouraged to stay informed about current cyclosporiasis trends, consult up-to-date travel health advice before departure and build basic food safety habits into their holiday routines. By paying closer attention to what they eat and drink, and by acting quickly if symptoms arise after travel, holidaymakers can continue to enjoy beach destinations even as public health agencies track this uncomfortable, but largely preventable, parasitic threat.