Details on the outbreak

Cyclosporiasis is a disease caused by the parasite cyclospora and is most common during the spring and summer months. People can be infected with the parasite if they consume food or water that's been contaminated with feces.

On July 1, CDC reported that there had been 145 cases of cyclosporiasis across 17 states between May 1 and June 16 that didn't involve travel outside of the country. However, the agency acknowledged there are now likely more cases throughout the United States.

Michigan, which was not included in the initial 17 states, reported more than 300 cases on Thursday, and said it has seen over 170 cases since June 22. According to Teena Chopra, a professor of medicine at the Wayne State University School of Medicine, Michigan typically sees only 50 cases of cyclosporiasis a year, and even the state's most recent numbers are likely an undercount since many people who are sick don't go to the doctor and get tested for the disease.

"This is the tip of the iceberg," Chopra said.

According to CDC and state health officials, New York, Texas, Illinois, and Michigan have reported the highest number of cyclosporiasis cases so far. Other states that have reported cases include:

• Alaska
• Colorado
• Connecticut
• Florida
• Georgia
• Louisiana
• Massachusetts
• New Jersey
• North Carolina
• Ohio
• Pennsylvania
• Tennessee
• Virginia
• Wisconsin

So far, at least 20 people have been hospitalized, but no deaths have been reported.

Symptoms of cyclosporiasis include cramps, nausea, loss of appetite, vomiting, fatigue, diarrhea, body aches, low-grade fever, and other flulike symptoms. Cyclosporiasis can last for a few days to over a month, and symptoms can come in waves, returning more than once after going away, CDC said.

Infections are typically treated with a combination antibiotic, but CDC noted that most people with healthy immune systems will recover on their own. CDC also said that it typically takes one to two weeks outside the body for the parasite to become infectious, which means human-to-human transmission is highly unlikely.

In the past, outbreaks have generally been traced to a single source like a large batch of produce that was distributed in a region or nationwide, said Luis Marcos, a professor of medicine and infectious disease physician at Stony Brook Medicine. For example, a 2022 outbreak in Florida was linked to bagged romaine lettuce in a Caesar salad kit.

Once the source is identified, "we'll know what not to eat," Macros said.

However, Chopra noted that identifying a source can be difficult because it can take around a week for symptoms to show up after an infection, and people have difficulty remembering what they ate.

So far, CDC says there is no evidence that the outbreaks across the country came from a single source.

Currently, CDC advises people protect themselves from cyclosporiasis by following general hygiene and food safety practices. The parasite is killed by heat, so cooking food normally takes care of it. According to Freeman, it's important to thoroughly wash all fresh produce before eating it, as washing "with a lot of water is certainly going to get the organisms off of there," he said.

However, Freeman noted that bleach doesn't kill the parasite, so bleach wipes won't work. Instead, thorough handwashing with soap and water and a follow-up with an alcohol-based hand sanitizer is safer.