Ask the Doctors

Dear Doctor: What's the deal with this new bug that made a bunch of people who ate raw vegetables get really sick? So much for trying to eat healthy!

Dear Reader: You're referring to an outbreak of cyclospora, an infection by a one-cell parasite that causes watery (and sometimes explosive) diarrhea. It enters the body when you eat food or drink water that has been contaminated with stool from someone who has been infected with the parasite.

At the time that we're writing this, there have been two distinct outbreaks of cyclospora this summer. In the first, 237 people in Minnesota, Iowa, Wisconsin and Michigan fell ill. According to the Centers for Disease Control and Prevention, that outbreak was traced to Del Monte Fresh Produce vegetable trays, which contained carrot and celery sticks, broccoli and cauliflower florets, plus a dill-flavored dip. Which component (or components) of the trays was contaminated by cyclospora is not yet known. A second outbreak in Texas, which sickened 56 people, has been also been reported. Health officials are working to track down the source of that outbreak and are also investigating whether the two outbreaks are linked in any way.

The infection, known as cyclosporiasis, can last anywhere from a few days to several weeks. In people whose immune systems have been weakened either by disease, such as HIV/AIDS, or through medical treatment, such as chemotherapy, the infection can last for several months. In addition to diarrhea, which can be quite severe, the infected individual can experience loss of appetite, abdominal cramps, gas or bloating, nausea or vomiting, as well as flulike symptoms such as fever, body aches and fatigue. Symptoms begin to arise anywhere from two to 11 days after the parasite has been ingested.

Because diarrhea has many possible causes, diagnosis of cyclosporiasis can be a challenge. Even in cases when a physician suspects that a parasitic infection may be the cause of a patient's symptoms, he or she must specifically request that cyclospora be included in the laboratory testing of stool samples. According to the CDC, repeated tests may be needed. That's because cyclospora is infectious only at a specific moment in its life cycle, when it produces something known as oocysts. Those may be shed intermittently and at such low levels that they can easily be missed.

A mild case of cyclosporiasis will clear up by itself. In these cases, it's sufficient to address the fluid loss that diarrhea causes by adequate hydration. However, when symptoms persist beyond a few days, it's important to seek medical help. Be prepared to tell your physician about any recent travel to tropical regions where cyclospora is common and any potentially contaminated foods you may have eaten.

A combination antibiotic known as trimethoprim-sulfamethoxazole (Bactrim, Septra) is commonly prescribed for more severe infections. Ciprofloxacin or nitazoxanide (Alinia) may be used as alternatives. You can track the latest information regarding these outbreaks at cdc.gov/parasites/cyclosporiasis/outbreaks/2018/a-062018/index.html.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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