For more than a decade working in infection prevention, Nicole Pirlot, RN, has seen her share of outbreaks. But nothing compares to the cyclosporiasis outbreak now sweeping across the Midwest.

In Michigan alone, thousands of people have become sick from the parasite this summer. According to the Michigan Department of Health and Human Services, the state has reported 8,176 cyclosporiasis cases and 160 hospitalizations, as of July 24, with just over 600 cases reported in one day. About 2% of those cases have led to hospitalization.

“Normally, we see in Michigan about 50 cases a year of cyclosporiasis,” says Pirlot, an infection preventionist at OSF HealthCare St. Francis Hospital & Medical Group in Escanaba, Michigan. “Most of those come from individuals who have traveled internationally in developing countries. We do see occasional cases locally in Michigan, but not at the extent we're seeing right now.”

Nine states now have related cases of diarrheal illness caused by iceberg lettuce contaminated with the microscopic cyclospora parasite, according to the U.S. Centers for Disease Control and Prevention (CDC). On July 24, the CDC added Illinois, Indiana, Kansas, Oklahoma and Pennsylvania to the cyclosporiasis outbreak investigation. A total of 41 states has reported at least one case since May 1.

Pirlot says people become infected by ingesting the cyclospora parasite, usually through contaminated food or water. Fresh produce, including fruits and vegetables, have been linked to outbreaks when it becomes contaminated. Scientists are still studying how long the parasite remains infectious under different temperatures, humidity, and agricultural conditions. This knowledge could improve prevention strategies.

Pirlot says symptoms include watery diarrhea, loss of appetite, weight loss, low-grade fever, cramping, bloating and increased gas, nausea and fatigue. “Studies show that you can start with symptoms two days to two weeks after eating,” Pirlot says.

Most healthy people will recover without long-term problems. However, it can last longer in people who are elderly, young children or people who are immuno-compromised. Seek medical attention if your symptoms become worse or you become dehydrated.

Cyclosporiasis is treatable with prescription antibiotics, so it's important to contact a health care provider if symptoms are severe or don't improve.

“(Especially) anyone who is feeling dehydrated, if they cannot keep their fluids up, starting to feel weak, multiple loose stools, or you're just not getting any better,” says Pirlot. “Come in, see your provider. They can help you out.” Consult with your medical provider to see if a virtual visit is an option.

Pirlot reminds people to always wash fruits and vegetables, which can reduce the risk of illness but won’t reduce the threat completely. Cooking food to at least 158 degrees Fahrenheit will help since heat destroys the parasite. For lettuce the recommendation is buying whole heads over chopped prepackaged kits and discarding those first outer layers before preparation.

“Good hand hygiene, washing those fruits and vegetables,” she adds. “Even if you're going to peel them, make sure you wash those skins and cook everything thoroughly. Use clean utensils. That way, you'll prevent all those other foodborne illnesses from undercooking and contaminated surfaces.”

Pirlot says the current outbreak serves as an important reminder that people can't control every source of contamination. The best defense is identifying symptoms early and seeking care when needed.

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Cyclosporiasis, caused by the parasite cyclospora, has made headlines this summer, as investigators work to identify its source. 

"It is a microscopic parasite. So, you can't see it with the naked eye," says Sharjeel Ahmad, MD, an infectious disease doctor with OSF HealthCare. "It causes an infection of the small intestine and produces a diarrheal illness."

As of July 14, nearly 7,000 cases of cyclosporiasis across 34 states are under investigation, with 141 people hospitalized, according to the U.S. Centers for Disease Control and Prevention (CDC). “This is substantially higher than the 249 cases reported nationally by this same time last year,” the CDC points out. Many of these cases are not connected to the Taylor Farms outbreak, which the CDC lists as having more than 1,644 cases as of Monday, July 20.

Michigan has reported the most cases so far, with health officials there recently identifying lettuce as a possible source.

How does cyclospora spread?

Unlike other gastrointestinal illnesses like norovirus, cyclosporiasis does not spread from person to person. Instead, the parasite must mature in the environment before it becomes infectious, a process that can take up to a week, Dr. Ahmad says.

"It's beginning at the farm," Dr. Ahmad says, adding that it spreads through fecal matter contaminating the soil and water, which then passes on to the food being grown.

Common foods affected are leafy greens like lettuce, as well as herbs, melons and berries.

"When the running water for irrigation gets contaminated, then the soil gets contaminated while you're growing raw produce," Dr. Ahmad adds. "It's meant to be consumed raw, but things like berries and lettuce have a big surface area with crinkles, cracks and crevices."

Contamination can also occur during harvesting if workers do not properly wash their hands after using the restroom.

How to reduce your risk

Wash each piece of produce individually.

"Washing may not make the risk go down to zero, but that's your best bet. Wash your hands first before you wash the products and then wash them individually," Dr. Ahmad says. "That will give you the most effective protection. Take the berries individually and washing them will help more than anything."

Refrigerating or freezing the products does not kill the parasite. Only cooking produce to 158 degrees Fahrenheit or hotter can kill it. Chemical washes and vinegar are not guaranteed to eliminate the parasite. Don’t use bleaches or other cleaners with your food, as they can cause health problems.

People who are pregnant or immunocompromised should be especially cautious, Dr. Ahmad says. During this time, Dr. Ahmad recommends that such people only eat leafy greens after they have been thoroughly cooked.

Cyclosporiasis symptoms to look out for

While explosive diarrhea has received the most attention, it is not the only symptom of cyclosporiasis. Other symptoms include:

• Bloating
• Cramping
• Fatigue
• Loss of appetite
• Low-grade fever
• Headaches
• Weight loss

Symptoms may come and go, meaning you may feel better for a period before they return, and they can last anywhere from a few days to a month.

Treatment options currently available

Treatment includes staying hydrated by drinking plenty of fluids and replacing lost electrolytes. An antibiotic called Bactrim, the brand name for trimethoprim-sulfamethoxazole, can be prescribed to kill the parasite and relieve symptoms.

Healthy adults may eventually clear the infection on their own as the immune system fights off the parasite. However, if your symptoms are severe, Dr. Ahmad recommends contacting your primary care provider to discuss testing. Routine stool tests do not screen for cyclospora, so a specialized test must be ordered.

Dr. Ahmad expects cases to continue increasing over the next few weeks before gradually declining. Historically, most cyclospora infections are reported between May and August, but this year is a much bigger outbreak than usual.

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