Cyclospora Outbreak Sickens Thousands Across US, CDC Investigates Salad Greens

Health authorities in the United States are investigating a large outbreak of cyclosporiasis, an intestinal illness caused by the parasite Cyclospora cayetanensis. According to the US Centers for Disease Control and Prevention (CDC), nearly 7,000 confirmed or probable cases have been reported across at least 34 states since May 1, making it one of the largest foodborne illness outbreaks in the country in recent years.

The CDC has confirmed 1,645 laboratory-confirmed cases, with more than 5,100 additional cases under investigation. This figure is significantly higher than the 249 cases recorded at the same point last year. The outbreak's epicentre appears to be the Midwest, with Michigan and Ohio reporting over 3,000 cases combined. Michigan alone has over 3,300 cases, according to CDC data cited by NBC News.

Investigators believe lettuce or salad greens may be the source, though no specific product, grower or supplier has been officially identified. Dr Natasha Bagdasarian, Michigan's chief medical executive, stated that early findings keep pointing toward a single culprit, but other foods cannot yet be ruled out. The CDC has linked cases across four Midwestern states—Michigan, Ohio, West Virginia and Kentucky—as part of a single connected outbreak of roughly 400 illnesses. Authorities are also examining a possible connection to Taco Bell restaurants, as reported by The Washington Post.

Cyclospora spreads when people consume food or water contaminated with human faecal matter, often through tainted irrigation water, poor farm labour conditions, or runoff into fields where produce is grown, per the CDC's explanation cited by CNN. Symptoms typically begin one to two weeks after exposure, starting with fatigue and body aches before progressing to sudden, watery diarrhoea, along with bloating, cramping and nausea. Unlike a typical stomach bug, the illness can last for weeks if untreated and is usually treated with the antibiotic Bactrim.

Cyclospora infections are notoriously hard to track. The parasite sheds intermittently in stool, meaning a single test can miss it, and it is not part of standard lab panels for stomach illness. Doctors often have to specifically suspect and order the test, as CNN reported. The two-week incubation period means confirmed cases reflect infections from weeks earlier, complicating efforts to pinpoint a source. Former CDC director Dr Robert Redfield told CNN that reduced federal surveillance funding has made early detection harder, warning that cutting such programmes is not in the country's interest since surveillance is key to early identification of outbreaks.

Only a handful of cyclospora outbreaks have exceeded 1,000 cases in the past two decades, including a 1997 outbreak linked to Guatemalan raspberries and a 2019 outbreak tied to Mexican basil, according to CNBC, citing food-safety researcher Melanie Firestone.

As speculation circulated online, several major food chains moved to reassure customers. Taco Bell said it had voluntarily and temporarily removed limited ingredients at affected locations. The company stated it is cooperating with health authorities to determine if its products are linked to the outbreak.