Health officials across the United States are investigating a widespread outbreak of cyclosporiasis, an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis, after confirmed infections were reported in more than half of the country’s states.
According to the US Centers for Disease Control and Prevention (CDC), the outbreak has reached 31 states, with hundreds of laboratory-confirmed cases recorded since early May. Public health officials believe the actual number of infections is likely much higher because many people recover without seeking medical attention or undergoing testing.
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Cases Continue to Rise Across Multiple States
CDC surveillance data covering the period from May 1 to July 9 identified 843 confirmed infections nationwide. The agency has also said it is reviewing more than 1,500 additional reports that may ultimately be linked to the outbreak, meaning official case totals are expected to increase as investigations continue.
Michigan has emerged as one of the hardest-hit states, reporting a sharp increase in infections over recent weeks. New York, Illinois and Ohio have also recorded unusually high numbers of cases compared with previous years. Although dozens of patients have required hospital treatment, health officials have reported no deaths linked to the current outbreak.
What Is Cyclosporiasis?
Cyclosporiasis is a gastrointestinal illness caused by the parasite Cyclospora cayetanensis. People become infected after consuming food or water contaminated with the parasite, most commonly through fresh produce exposed to contaminated irrigation water or unsanitary conditions during production.
Unlike some other intestinal infections, cyclosporiasis is not typically spread directly from one person to another because the parasite must mature in the environment before it becomes infectious.
Symptoms usually begin about one week after exposure and commonly include:
- Frequent watery diarrhoea, which can become severe or explosive
- Stomach cramps
- Loss of appetite
- Nausea
- Fatigue
- Bloating and gas
Without treatment, symptoms may continue for several weeks and, in some cases, return after temporarily improving.
Investigators Have Not Yet Identified the Source
Federal and state health agencies are working to determine which food item introduced the parasite into the food supply.
So far, investigators have not identified a specific grower, distributor or produce item responsible for the current outbreak. The CDC has said affected patients became ill after eating food in the United States and had not recently travelled abroad, suggesting the contamination occurred domestically.
Previous cyclosporiasis outbreaks have been associated with a variety of fresh produce, including bagged salad mixes, cilantro, basil, raspberries, leafy greens, snow peas and green onions. Because contamination often occurs during farming or irrigation, tracing infections back to a single source can be particularly difficult.
Health Officials Urge Food Safety Precautions
While investigators continue tracing the outbreak, public health authorities are encouraging consumers and food businesses to reduce their risk through careful food handling.
Experts recommend thoroughly washing fruits and vegetables under running water, even though washing alone may not eliminate every parasite. Cooking produce where practical provides additional protection because heat can destroy Cyclospora. Restaurants and commercial kitchens have also been advised to strengthen produce handling procedures while the investigation remains active.
Anyone experiencing persistent diarrhoea or other symptoms consistent with cyclosporiasis is encouraged to seek medical evaluation. The illness is treatable with antibiotics, and early diagnosis can help prevent prolonged illness and dehydration.
Investigation Remains Ongoing
The CDC expects additional cases to be identified as laboratories complete testing and state health departments submit new reports. Until investigators pinpoint the contaminated food source, officials are likely to continue monitoring infections nationwide and updating guidance as more evidence becomes available.
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