Cyclosporiasis outbreak reaches nearly 7,000 cases in the US
A parasitic illness causing severe, explosive diarrhoea has spread rapidly across the United States, infecting nearly 7,000 people across 34 states, according to the US Centers for Disease Control and Prevention (CDC). At least 145 people have been hospitalised, and more than 5,100 additional cases are under investigation. The outbreak, caused by the microscopic parasite Cyclospora cayetanensis, has prompted concerns among UK travellers visiting the US for the World Cup, though the parasite is not endemic in the UK.
What is cyclosporiasis and how is it spread?
Cyclosporiasis is an intestinal infection caused by ingesting food or water contaminated with Cyclospora. Past outbreaks have been linked to fresh produce such as salads, herbs, raspberries, and lettuce that were not properly washed or cooked, the Guardian reported. Unlike contagious diseases like COVID-19, cyclosporiasis cannot be transmitted from person to person. The main symptom is frequent, watery diarrhoea that can be explosive, along with stomach cramps, nausea, fatigue, and loss of appetite. Most people recover without treatment within days or weeks, but those with weakened immune systems may require antibiotics.
Why is tracing the source so difficult?
Cyclosporiasis symptoms can take up to two weeks to appear, making it extremely challenging to identify the contaminated food source. Investigators must interview all confirmed cases to recall what they ate in the two weeks prior, then wash large quantities of suspect produce and test the run-off for the parasite. Steven Manderach, executive director of the Association of Food and Drug Officials, told the BBC the search is like looking for 'a microscopic portion of a needle in a haystack.' The difficulty is compounded by a time-consuming testing process and reduced public health funding following Trump administration cuts, which have hampered outbreak monitoring and investigation.
Despite these challenges, officials in Michigan, Ohio, West Virginia, and Kentucky have confirmed a link between cases. Health officials in Michigan have suggested that lettuce served at Taco Bell restaurants in the state may be a potential source.
Should people in the UK be worried?
For most UK residents not travelling to the US, the risk is low because cyclosporiasis does not spread from person to person. However, UK travellers to the US—especially those attending the World Cup—should exercise caution with fresh produce. Health officials recommend thoroughly washing all fresh fruit and vegetables or cooking them. The parasite is also found in parts of Central and South America, South and Southeast Asia, the Middle East, and Africa.
The NHS advises travellers to these regions to: wash hands regularly with soap and clean water or use alcohol hand gel; drink only bottled, boiled, or purified water; eat thoroughly cooked food; stick to fruit that can be peeled, such as bananas or oranges; and drink hot drinks made with boiling water or sealed drinks. The NHS also recommends avoiding salads, raw vegetables, fruit washed in tap water, ice in drinks, and tap water for drinking or brushing teeth.
What to do if you suspect cyclosporiasis
If you develop persistent, watery diarrhoea after travelling—especially if it does not clear up within a few days—see your GP and mention your travel history. Cyclosporiasis is not always included in standard stool tests, so you may need to specifically request testing. Most cases resolve on their own, but antibiotics can be prescribed for severe or persistent symptoms. Stay well hydrated in the meantime.
