What to know about cyclosporiasis as the parasitic infection is found in 34 states

An intestinal parasite that causes “explosive” diarrhea is sickening people across 34 states, the Centers for Disease Control and Prevention said Tuesday.

Despite outbreaks affecting two states bordering Pennsylvania, the Philadelphia region so far shows no signs of widespread illness from Cyclospora cayetanensis.

Speaking to reporters, federal health officials said they had linked cyclosporiasis cases in a widespread outbreak in Michigan, Ohio, Kentucky, and West Virginia. Michigan alone had reported more than 3,000 cases by Tuesday.

“It’s a much higher number than we typically see in a cyclosporiasis season — much, much higher than last year or the year before,” said Gwen Biggerstaff, the deputy director of CDC’s Division of Foodborne, Waterborne, and Environmental Diseases.

Reporting requirements for cyclosporiasis cases differ in Pennsylvania, but cases here remain relatively low. Cases were also at typical levels in New Jersey, and none has been reported in Delaware since May.

Here’s what you need to know about the parasite and how to prevent it:

Cyclosporiasis is caused by a single-celled parasite, cyclospora, that spreads through fecal material. It can infect a person’s gut after consuming food or water contaminated by feces.

Common symptoms include watery diarrhea, a loss of appetite, cramping, nausea, and fatigue. Past outbreaks have been associated with leafy greens and other produce, said Rosemary Trout, an associate professor of food science at Drexel University.

The disease doesn’t spread directly from person to person. It becomes infectious after one to two weeks outside the body, and infected people may not immediately develop symptoms.

“It can take two days to two weeks for symptoms to appear,” said Akhil Vaidya, a distinguished professor in the Department of Microbiology & Immunology at Drexel’s College of Medicine.

“That has been the challenge for tracking where the parasite came from. Most likely it’s in some produce, but which produce it’s coming from is not really clear. People don’t remember what they ate two weeks back.”

Health officials in 47 states, including New Jersey and Delaware, are required by law to report cyclosporiasis cases to the CDC.

Pennsylvania is among a handful of states where doctors are not required to report cases to health officials, but they do so on a voluntary basis, and state officials investigate and submit case reports to the CDC.

A federal foodborne illness surveillance system, FoodNet, stopped tracking cyclosporiasis last year.

But that program’s goal is to “look at trends over time to inform policy and prevention activities,” not monitor active outbreaks, and only drew data from 10 sites around the country, the CDC’s Biggerstaff said.

“[FoodNet] doesn’t give us the data we have from national surveillance,” she said. That broader program is “unchanged,” she said.

Though Pennsylvania borders Ohio and West Virginia, two states involved in an ongoing outbreak, cases here have been relatively low. So far this year, state health officials have reported 28 cases, 14 of them in Southeastern Pennsylvania.

New Jersey has reported between 31 and 80 cases since May, when cyclosporiasis cases typically rise, according to the CDC. But health officials there said last week that the state is experiencing “normal seasonal circulation without known clusters or outbreaks.”

Delaware has not reported any cases since May 1, the CDC said.

Cases in Michigan, Ohio, Kentucky, and West Virginia are considered part of a “multistate outbreak” that is likely tied to a common source, Biggerstaff said. But it’s still unclear what that source is.

Though the CDC has lagged behind states in confirming cases so far, the agency has confirmed 1,645 cyclosporiasis cases since May, and is monitoring 5,100 additional reported cases that will “require additional analysis to confirm,” Biggerstaff said.

Good handwashing practices are the first line of defense against cyclosporiasis: Wash your hands for at least 20 seconds in hot, soapy water.

Washing produce also helps, but rinsing does not necessarily remove all traces of cyclospora, said Trout, the food safety professor. Heating produce to 150 degrees Fahrenheit can kill the parasite.

Trout said that higher-risk groups — immunocompromised people, young children, elderly people, and pregnant women — may want to avoid fresh produce and instead opt for frozen or canned fruit and vegetables.

Most of those products have been treated with heat at some point in their packaging process.

“If you are in a high risk population, or very worried about it, it’s valid,” she said. “The case number is very high, and it’s proximate to our state.”