More than 400 cases of cyclosporiasis, the diarrhea-causing parasitic infection sweeping the country, have been identified in New York City this year, health officials said Tuesday. Ninety-three percent of them have come in the last 10 weeks. “The NYC Health Department is currently investigat ing a rise in cyclosporiasis cases, which can cause watery diarrhea, stomach cramps, and nausea,” the health department said in a statement Tuesday. “We are working with our partners to determine a common source.” The state health department didn’t immediately respond to a request for updated data Tuesday. Last week, on July 9, they said 394 cases statewide had been identified since May 1. Nearly 70% of those were in the city. The spike isn’t limited to the five boroughs. Cyclosporiasis has been spreading across the United States in recent weeks. Michigan has confirmed more than 3,300 cases in what has become the largest such outbreak in the state’s history. At least 34 states are reporting cases, according to the CDC. The CDC’s data lags state data. In a Tuesday update, the CDC said it had gotten 1,645 confirmed U.S. reports and was investigating 5,100. Nine percent of those people have been hospitalized. None have died. The true case count, though, is likely higher, health officials acknowledge. Some people recover without needing treatment, or even knowing they were infected, driving down official numbers. Health officials in Michigan, the epicenter of the outbreak, say their testing indicates lettuce or salad greens as a potential source. The CDC said in a telebriefing Tuesday that no food source had been confirmed at this time. Cyclosporiasis cases can rise in the spring and summer months — especially from June through August — though cases are reported year-round. 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. Health wellness Jul 9 What is cyclosporiasis, the ‘explosive diarrhea' parasite infection tied to produce? Health Jul 7 Cyclosporiasis outbreaks: What to know about the foodborne illness and symptoms 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 abated 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. ...read more read less