Summer is peak season for beach trips, barbecues and — unfortunately — a microscopic stomach parasite that causes explosive diarrhea called Cyclospora cayetanensis. The parasite that causes this illness, Cyclospora, is considered a nationally notifiable disease, which means healthcare providers are legally required to report cases to the federal government so the Centers for Disease Control and Prevention can monitor outbreaks and prevent their spread. As of June 16, the CDC is tracking 145 cases of the intestinal illness across 17 states, but health officials emphasize this is a seasonal occurrence and it’s highly treatable, even if it’s hard to trace. Patients range in age from 5 to 86 years, and 61% are women. Twenty were hospitalized, and no deaths have been reported. The people told health officials they got sick after eating U.S.-based food and did not travel 14 days prior to getting sick. The CDC’s numbers are just the tip of the iceberg. The CDC also notes that the actual number may be higher than 145 infections, but that’s usually the situation with reportable diseases, Dr. Bobbi Pritt, Chair of the Division of Clinical Microbiology at the Mayo Clinic, told HuffPost. “It never really completely reflects all the cases,” she said, “because of all those things that go into play of someone thinking about it, ordering the right test, and making sure it’s reported.”GettyThe majority of the cases are congregated in New York State — where there are between 31 and 80 cases — with many in Texas and Illinois, too.According to Pritt, it’s common there are likely a number of people who have mild symptoms who wait it out and don’t get tested, a number of people who go to the doctor but don’t take the right test, and a number of people whose cases weren’t reported to the CDC. “We see that with all the reportable diseases,” she said. Cyclospora is also not detected by a simple stool test and requires an additional stain, which isn’t part of the standard repertoire of testing, Pritt added. Here’s where the outbreak is spreading — and why it’s happening now. The majority of the cases are congregated in New York State — where there are between 31 and 80 cases — with many in Texas and Illinois, too. There are also cases present in Alaska, Colorado, Connecticut, Florida, Georgia, Louisiana, Massachusetts, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia and Wisconsin. Case counts typically rise during the spring and summer months because the parasite thrives in tropical and subtropical regions, the CDC said, so the cyclosporiasis season is considered to be May 1 through Aug. 31. This year, the first reported case was on May 13. “This is a season where we get more fresh produce coming in,” Pritt said. “People are eating more salads and herbs and berries and vegetables that are often eaten raw, and therefore, it’s more likely that if there are parasites present, they’d still be active in a live plant instead of being cooked, which would inactivate them.”Since this is a recurring infection, the CDC has developed more molecular genetic analyses to examine the DNA of these organisms, Pritt told HuffPost. It’s not just about detecting the parasite, but also about identifying each type and determining whether it’s related to outbreaks in other states.“That really helps them track it,” she said. “They could type the parasite from the people infected in all those different states and see if it’s even coming from the same source. If they’re [not] all related, it could be that they’re unrelated and maybe there is multiple different infected produce supplies coming into the country.” You cannot catch this from another person. There is no evidence that the disease can spread person-to-person; it is more likely to be transmitted through contaminated food. “If one person in the household is sick, they’re not going to be able to spread it to other people,” Pritt said. “Now, other people in the family might get it if they eat the same food, but it’s not going to spread person-to-person through shedding virus like norovirus.”Imported fresh produce, including basil, cilantro, raspberries and snow peas, has been traced to cyclosporiasis in the past, according to the CDC. The parasite, which is shed in human stool, is likely present in the soil where produce is grown for export to the U.S., so it settles into the food supply, Pritt said. “It isn’t like some of the other parasites we find in the U.S., where they could be shed by animals. This is really a human disease, and it’s associated with poor hygiene, human fecal waste entering the food supply, and that food then being shipped to the U.S. via imported produce,” she said. Patients typically experience these symptoms within a week after consuming the contaminated food or water. “It lasts a little longer than the typical 24-hour stomach bug,” Pritt said. “The hallmark is really prolonged watery diarrhea, and it’s very often accompanied by abdominal cramping, abdominal pain, bloating, nausea, fatigue and loss of appetite.”The infection and its symptoms can go away without antibiotics, but sometimes, without proper treatment, the symptoms could last longer than a month — fatigue, specifically, can persist even after gastrointestinal symptoms subside, according to the CDC. How to safely handle your summer produce. Experts do not fully understand how Cyclospora gets into food and water, but the best way to prevent contracting the parasite is to wash hands with soap and water before and after handling raw fruits and vegetables. Produce should also be washed under running water before being consumed or prepped — even if it is labeled “prewashed.” Certain firm foods, like melons and cucumbers, should be scrubbed with a produce brush. However, it is important to note that chemical disinfection or sanitization is unlikely to fully kill the Cyclospora parasite. “For the most part, I would say our produce is pretty safe,” Pritt said. “Most of the time, fresh produce in general is very safe, and it’s actually an important part of a healthy diet, so we wouldn’t want people to stop eating it. But I do think it’s important to note that at this point, if someone becomes symptomatic and they develop prolonged watery diarrhea, they go to their healthcare provider.”