Cyclosporiasis outbreak: Lettuce under investigation as source

Lettuce is being investigated as a possible source of a large cyclosporiasis outbreak in the US, with health officials urging consumers to follow food safety practices while the investigation continues.

The parasitic infection, which commonly causes severe diarrhoea, has sickened thousands of people, with Michigan reporting the highest number of cases. Officials say lettuce has repeatedly appeared in patient interviews and traceback investigations, although no specific type, grower or supplier has been identified.

Why lettuce is under investigation

Cyclospora, the parasite that causes cyclosporiasis, can contaminate lettuce through polluted irrigation or wash water, as well as during harvesting, processing or distribution.

Experts say leafy greens are especially vulnerable because their folded leaves can trap the parasite, and they are usually eaten raw, meaning there is no cooking step to kill harmful organisms.

While lettuce is the leading suspect, investigators have not ruled out other fresh produce. Previous cyclosporiasis outbreaks have also been linked to cilantro, basil, raspberries, snow peas and green onions.

How to reduce your risk

Health experts are not advising people to stop eating lettuce but recommend following safe food handling practices.

Consumers should wash their hands before preparing food, rinse produce under running water and, when possible, buy whole heads of lettuce instead of pre-packaged salad mixes. Removing the outer leaves and thoroughly washing the remaining inner leaves may also help reduce contamination.

People who develop symptoms such as watery diarrhoea, nausea or flu-like illness should seek medical attention. Cyclosporiasis can be confirmed through stool testing and is treatable with antibiotics.

Officials continue to investigate whether the cases stem from a single nationwide outbreak or multiple unrelated outbreaks involving different food sources.