An outbreak of a parasitic infection that causes severe diarrhea has sickened nearly 400 people in New York since the beginning of May, the majority of which have been in New York City, according to state health officials.
Cyclosporiasis has been spreading across the United States in recent weeks. Michigan has seen nearly 1,000 cases already in what has become the largest such outbreak in the state’s history, and one the nation’s largest in years.
New York’s Department of Health said Thursday there had been 394 cases found in the state since May 1. Of those, 273 were found within the five boroughs, with 121 throughout the rest of the state, the department said.
“While cyclosporiasis is not likely to spread directly from one person to another, and is generally not life-threatening as many people with healthy immune systems recover without treatment, the Department encourages all New Yorkers to be aware of the best practices to prevent Cyclospora and other infections common in the summer months,” the Health Department said in a statement.
Officials noted that there was no evidence of a single, multistate cyclospora outbreak that would link all the cases. The department said it would continue to work with the Centers for Disease Control and Prevention, U.S. Food and Drug Administration and local health departments in order to determine any possible sources of exposure.
Cyclosporiasis cases can rise in the spring and summer months, though cases are reported year-round and the current case count is not unusual for this time of year.
What is cyclospora?
Cyclospora is a microscopic, spherical parasite that commonly causes watery diarrhea “with frequent and sometimes explosive bowel movements,” according to the U.S. Centers for Disease Control and Prevention. The illness, called cyclosporiasis, is not usually life threatening and is typically treated with antibiotics. Outbreaks tend to occur most often in the late spring and summer.
The heat-loving parasite infects the bowels and spreads through feces. In the past, people have been infected by consuming fruits or vegetables that were exposed to feces-contaminated irrigation water.
It’s less common than a number of other kinds of foodborne illnesses, including salmonella and E. coli. For years, few U.S. cyclospora outbreaks were reported each year. But the number started rising about a decade ago, with a particularly notable spike in 2018 and 2019. Experts attribute the increases to climate change and better detection.
How does this outbreak compare to previous ones in the US?
Comprehensive data on cyclospora outbreaks is lacking. But available information shows only a small number of documented outbreaks in the last 20 years have surpassed 1,000 cases. That short list includes a 1997 outbreak tied to Guatemalan raspberries that sickened more than 1,000 in the U.S. and Canada, and a 2019 outbreak linked to Mexican basil that sickened more than 2,400.
There are several reasons it’s challenging to know the exact toll, said Melanie Firestone, a University of Minnesota foodborne illness researcher. Some tests used to check for types of food poisoning are not geared to detect cyclospora, “so there is a lot of underreporting when it comes to this,” she said.
Other challenges: Technicians aren’t able to grow the parasite in labs, making it hard to draw evidence from contaminated produce. And it can be hard to figure out what food sick people had in common, because sometimes it’s a single ingredient that might be common in multiple recipes — like basil or cilantro.
Also, it’s possible that food distributors may channel contaminated foods to both grocery stores and restaurants, making it hard to discern where tainted food came from. Investigations can take months and sometimes never find a clear source.
What’s the current situation?
Cases seem to be surging in and around southeastern Michigan. But it’s not considered a national health emergency.
There’s no evidence that the parasite has evolved to become more infectious, said Dianna Blau, the CDC’s acting parasitic diseases branch chief.
Thousands of cyclospora illnesses are reported in the U.S. each year and it’s not yet clear how unusual this year will be, she added. That said, the case total so far is four times higher than at the same point last year, according to current CDC national data, which lags dramatically from what’s being reported by the states.
Michigan appears to be suffering the worst of it, but the state’s aggressiveness in investigating and reporting cases may be “part of the reason why this looks like a Michigan problem,” Bagdasarian said.
How can you protect yourself from cyclospora?
People who have diarrhea that hasn’t gone away on its own within a few days should see a health provider and discuss the possibility of cyclospora, officials say.
The best way to prevent infection with a parasite is to avoid food or water that may have been contaminated.
Fresh produce should be thoroughly washed before being eaten. But be aware that cyclospora can really stick to some foods, so washing may not eliminate the risk of infection.
As Michigan officials investigate the potential source, they recommend consumers purchase whole heads of lettuce rather than prewashed, bagged lettuce or salad mixes, and to remove the outer two to three leaves before washing the remaining leaves under running water.
They also say to cook vegetables when possible.