(HealthDay)—As U.S. health officials continue to try to track down the source of a widespread stomach bug outbreak, the number of confirmed illnesses keeps climbing.
According to the latest statistics from the U.S. Centers for Disease Control and Prevention, posted on its website Wednesday, 504 cases of infection with the cyclospora parasite have now been reported in 16 states and New York City, with 30 patients hospitalized in five of those states.
Earlier this week, the source of the outbreak in at least two states was traced to a Mexican farm that supplied salad mix to Olive Garden and Red Lobster restaurants.
The U.S. Food and Drug Administration announced on its website Sunday that illnesses in Nebraska and Iowa have been traced to Taylor Farms de Mexico, the Mexican branch of Taylor Farms in Salinas, Calif. The FDA said that it was trying to determine whether the prepackaged salad mix was the source of infections in the other states.
"It is not yet clear whether the cases reported from other states are all part of the same outbreak," the agency said in its statement. "The investigation of increased cases of cyclosporiasis in other states continues."
Taylor Farms chairman and CEO Bruce Taylor said in an email earlier this week that the plant involved produced 48 million servings of salads for thousands of restaurants in the Midwest and eastern U.S. in June, the month the outbreak started, the AP reported. He added that the plant has an extensive water-testing program.
"All our tests have been negative and we have no evidence of cyclospora in our product," Taylor said in the email. "We are working closely with the FDA to continue this investigation."
Taylor noted that Taylor Farms de Mexico does not supply Olive Garden and Red Lobster restaurants in Texas, the state that now has the highest number of illnesses in the outbreak.
According to the CDC, 190 of the illnesses reported so far were in Texas. Iowa has had 153 illnesses and Nebraska has had 85.
Meanwhile, U.S. health officials said the overall investigation continues.
In a posting on its website, the CDC said that it "will continue to work with federal, state and local partners in the investigation to determine whether this conclusion applies to the increase in cases of cyclosporiasis in other states. It is not yet clear whether the cases from all of the states are part of the same outbreak."
Prior outbreaks of cyclospora infection have typically been caused by tainted produce, the agency noted.
Cases have now been reported in Arkansas, Connecticut, Florida, Georgia, Illinois, Iowa, Kansas, Louisiana, Minnesota, Missouri, Nebraska, New Jersey, New York, Ohio, Texas and Wisconsin.
One expert said that while cyclospora can make people very ill, it is not usually life-threatening.
"On the infectious disease scale, this ranks well below the more notorious and dangerous ailments like E. coli and salmonella," said Dr. Lewis Marshall Jr., chairman of the outpatient services at Brookdale University Hospital and Medical Center in New York City.
"It is unlikely to be fatal, but certainly can make one's life miserable," he added. "Symptoms include crampy abdominal pain, watery diarrhea, loss of appetite, bloating, nausea, fatigue, fever, headache and body aches."
Cases of cyclosporiasis are caused by a single-celled parasite and cannot be spread from person to person; it has to be ingested via contaminated water or foods such as fruit and vegetables, according to Dr. Monica Parise, chief of the parasitic diseases branch at the CDC.
"It can be pretty miserable, because it can give diarrhea that can last for days," Parise said.
It takes about a week for people who are infected to become sick.
Marshall said there may be more cases of cyclospora infection out there than people realize. It is possible "that most occurrences go unreported, as many people wouldn't recognize the symptoms as any different than a common stomach bug," he explained.
Dr. Thomas Frieden, CDC director, urged people who have suffered from diarrhea for longer than a couple of days to be tested for cyclospora.
"If not treated, symptoms can last from a few days to a month or longer, go away and then return later," Marshall said. "Cyclospora can be treated with an antibiotic combination of trimethoprim-sulfamethoxazole [Bactrim]."
The best option, however, is to avoid the bug altogether.
"The safest way to protect oneself and one's family is to always rinse fresh produce under water, and even put vegetables in a cold water bath ahead of time to properly clean them," Marshall advised.
One expert stressed that the wash-your-produce rule includes prepackaged salads.
"Wash all your fruits and salads before ingesting," said Dr. Salvatore Pardo, vice chairman of the emergency department at Long Island Jewish Medical Center in New Hyde Park, N.Y. "My hunch is the public does not do this to 'prepackaged' salad, which is normally purchased for convenience and dumped into the bowl since it tends to be free from particles—dirt, sand, critters—one would normally find in locally picked ingredients."
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For more information on cyclospora, visit the U.S. Centers for Disease Control and Prevention.