Nearly 3,000 people have contracted a gastrointestinal illness called cyclosporiasis, a foodborne infection characterized by severe, watery diarrhea, according to state health departments across the country. The Centers for Disease Control and Prevention reported Friday that 31 states have reported cases of cyclosporiasis and 86 people have been hospitalized.
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As health officials struggle to find the source of the illnesses, the CDC said it is unclear whether outbreaks in different states are connected.
The numbers represent a sharp increase compared to this time last year, he said. The agency has confirmed 843 of those cases, all acquired in the US, and is still investigating more than 1,500. No deaths have been reported.
The outbreak has been particularly intense in Michigan, which had 1,562 cases as of Friday. Diseases caused by the cyclospora parasite, Cases have also been reported in neighboring Ohio, as well as in Colorado, Illinois, New York, North Carolina, Texas, Wisconsin and other states.
Dr. Natasha Bagdasarian, Michigan’s chief medical officer, said the rapid increase is “very unusual.” The state typically sees between 40 and 50 cases of cyclosporiasis a year. He said state labs are scrambling to sequence the insect’s genome to track where it came from.
“We can see if the isolates are closely related, meaning there was probably a common source, and then we can potentially go back and look for the source of that contamination,” he said.
Historically, fresh produce has been behind outbreaks. Cyclospora parasites attach to fruits, vegetables, and herbs, making them difficult to rinse off.
Dianna Blau, acting chief of the CDC’s Division of Parasitic Diseases, said it’s challenging to investigate outbreaks because symptoms can take a week or more to appear. “In an average year, there is a small proportion of cases that can actually be traced back to a particular food,” he said.
Whatever is making people sick now was probably consumed over a week ago. Very often, contaminated foods are combined with other foods (cilantro in sauce or bagged lettuce in salads, for example) and are easily forgotten days later.
As of Friday, the Food and Drug Administration said it was “actively engaging” with state partners. There have been no recalls of products possibly related to the outbreaks.
Where is it spreading?
Michigan has been hardest hit this summer, the season when cyclosporiasis cases typically occur. The state had confirmed 1,562 cases as of Friday, with at least 36 hospitalizations. Most are concentrated in the southeast corner of the state that borders the northwest part of Ohio, which is also experiencing an outbreak.
The Ohio Department of Health had 177 cases listed, with 28 people hospitalized, as of July 2. Those numbers are sure to increase, because the Toledo-Lucas Health Department reported 306 cases last week. New York has reported 394 cases and Illinois has 141 cases so far.
An NBC News tally of state health department data shows 2,912 cases have been reported or confirmed nationwide. Last year, there were approximately 2,700 cases nationwide, Blau said. Cases tend to increase during the summer, generally between May 1 and August 31.
What is cyclosporiasis and what are its symptoms?
The disease, cyclosporiasis, is a foodborne illness caused by a microscopic parasite called cyclospora. Fresh produce is almost always the source. Previous outbreaks have affected raspberries, lettuce or bagged salads, cilantro and basil. In rare cases, it can also be transmitted through water.
Regardless of how it enters the human body, people usually start to feel unwell about a week later. The illness may begin with flu-like symptoms, such as severe fatigue and body aches.
What really sets the symptoms apart from cyclosporiasis is the explosive, watery diarrhea that is sometimes uncontrollable. People may also have unusually bad gas, stomach cramps, and nausea. As a result, most people lose their appetite. Low fevers are rare.
Cyclosporiasis is treated with an antibiotic, usually Bactrim. If left untreated, symptoms can persist for weeks. People who suffer from this disease need to drink plenty of fluids to counteract diarrhea.
On average, 10% of patients need to be hospitalized, often for dehydration, Blau said. Young children, older adults, and other people with compromised immune systems are most at risk.
Test results usually take about 24 hours. In some areas, however, the demand for testing has stretched the turnaround time to two or three days, doctors said.
How is the disease tracked?
In July of last year, the CDC made cyclospora monitoring optional by scaling back its Foodborne Illness Active Surveillance Network. At the time, food safety experts were concerned that actions like this and other cuts at the CDC would make it harder to identify and respond to outbreaks.
Donald Schaffner, professor of food microbiology and chair of the Department of Food Sciences at Rutgers University, said it’s unclear whether that made a difference in the current outbreaks of cyclosporiasis.
“Could we have learned sooner? Could we be discovering more?” said. “We need to do more to track them.”
The CDC’s Blau said there have been no differences in how cyclosporiasis cases are reported or handled at the agency in recent years.
State and local health departments are responsible for interviewing patients to see if they can remember what they ate in the past few weeks that might be the culprit, as well as analyzing grocery receipts to look for similar brands of food products. Blau said the CDC is providing technical assistance to states and helping analyze samples as researchers try to determine if they are linked to other outbreaks.
How is it spread?
The disease does not spread from person to person like a respiratory virus or norovirus, another stomach virus. Even when a person sheds the parasite through bowel movements, the parasite is not mature enough to infect other people right away.
It takes days or weeks for these parasites to grow in the environment before they become strong enough to cause a new infection.
And although cyclospora is not known to remain on surfaces, food safety experts always recommend washing countertops and cutting boards with soap and water.
Staying safe from cyclosporiasis
Cooking food is the only sure way to kill the parasite. Rinsing produce may reduce the risk of cyclosporiasis, but it does not eliminate it.
Janet Buffer, senior director of the Institute for Food and Nutrition Security at George Washington University, recommends against using dishwashing soap because it could leave residue on the surface of fruits and vegetables, which could also upset your stomach.
Instead, “shake the surface vigorously,” he said.
Raspberries in particular can be difficult to clean because they are covered in small hairs that make it easy for the parasite to attach to them. There is no indication that the berries are involved in the current outbreaks. The country’s largest berry supplier, Driscoll’s, told NBC News that it has not been contacted by health authorities regarding any connection to the increase in cases.
The Michigan Department of Health and Human Services suggests cooking raspberries when possible, such as in pies and jams. It is possible that freezing could kill the parasite, but it is not guaranteed.
Other tips to reduce the risk of cyclosporiasis, according to Michigan health officials:
- Buy whole lettuce instead of pre-washed bagged lettuce or salad mixes. Remove the outer leaves and rinse the remaining leaves.
- Separate the coriander and basil leaves and wash them well under running water.
- Trim the green onions by removing the root end and removing the outer layer before washing.
Until a source is found, Rutgers’ Schaffner warns against eating fresh fruits and vegetables. “We know that fresh produce is part of a healthy diet. We know that cyclospora cases peak between May and August, which is also the main season for fresh produce consumption,” he said. “I can tell you that I am not going to change my consumption habits.”
