This undated photo taken through a microscope provided by the CDC shows Cyclospora cayetanensis oocysts found in a fresh stool sample which had been prepared with a formalin solution and stained with safranin. (CDC via AP)

Several cases of a parasitic illness that’s spreading across the country have been reported in Alaska, state public health officials say.

As of Thursday, five cases of cyclosporiasis had been reported throughout the state, according to a Department of Health bulletin issued through the Alaska Public Health Alert Network. The first case of the intestinal illness was reported here in May, according to the alert.

People can be become ill when they consume food or water contaminated with feces containing the Cyclospora parasite. The illness often results in watery diarrhea in frequent, intense bowel movements, according to the Centers for Disease Control and Prevention.

The alert comes as the number of cases surges nationwide, the CDC said: Cyclospora had sickened about 1,650 people nationwide since May as of Wednesday, with another 5,100 or so potential cases that have not yet been confirmed.

In Alaska, all of the illnesses involve adults, officials said.

The Alaska cases haven’t resulted in any hospitalizations, public health officials said. Nearly 10% of those sickened in the U.S. have been hospitalized, the CDC said.

Three of the Alaskans who contracted the disease had traveled internationally before becoming sick, according to the state alert. One person reported out-of-state travel and exposure to fast food, state officials said. The fifth case involved someone who hadn’t traveled outside Alaska, according to the bulletin.

It’s unclear if Alaska’s cases are tied to the same source of the larger outbreak in the U.S., said state epidemiologist Dr. Joe McLaughlin.

Cyclosporiasis cases are most likely to occur between May and August and typically come from eating fresh produce contaminated by feces-tainted water, he said.

Alaska public health officials said no single food item, grower or supplier has been identified as the source of the outbreak, but the Washington Post reported on Thursday that investigators had identified lettuce supplied to Taco Bell restaurants as the potential source of the wave of illnesses.

Generally, most people who end up being hospitalized due to the parasite are young children, older adults or people with weakened immune systems suffering with severe dehydration from prolonged diarrhea, McLaughlin said.

Those with the illness should drink plenty of water, with added electrolytes, he said. Antibiotics can also help reduce the severity and duration of the sickness.

A sickened person could also experience several bouts of diarrhea over a prolonged period, McLaughlin said. Other symptoms include appetite loss, fatigue, nausea and a low-grade fever.

While most people recover completely, “unfortunately, this particular illness can linger for weeks, and in some cases, even months,” he said.

About 250 cyclosporiasis cases in the U.S. were reported from May to July 16 of last year, according to the CDC. In Alaska, about five cyclosporiasis cases are reported to state health officials a year, according to Thursday’s bulletin.

The most effective way to prevent cyclosporiasis is to thoroughly wash fresh fruits and vegetables before eating them, McLaughlin said.

“Even if it’s labeled as pre-washed, go ahead and clean it. One of the things with these cyclospora protozoans is that they cling pretty tightly to produce,” he said. “They’re also resistant to routine chemical disinfection. So, the better you wash your fruits and vegetables, the more likely you are to get most of that cyclospora off of them.”

McLaughlin also said it was important to avoid cross-contaminating surfaces or utensils while cooking and to wash hands frequently. Cooking produce to a temperature of at least 158 degrees will also kill the cyclospora, he said.

In the state alert, officials asked Alaska healthcare providers, laboratories and tribal health organizations to watch out for patients with prolonged or relapsing watery diarrhea and to test those with symptoms. Officials also asked health care providers to report suspected or confirmed cases to the state Section of Epidemiology.