“The oysters on the half shell were the specialty of the house,” Brian explained, “and as much as I love raw oysters, I knew they could make me sick, so I didn’t have any. In fact, that’s what bothers me most — I don’t really know how I got so sick.”

Brian was in my office explaining the details of his recent Caribbean vacation. A few days after returning from a weeklong trip, he had come down with such severe gastrointestinal symptoms (nausea, cramps, and diarrhea) that he’d gone to the emergency room. He ended up spending several days in the hospital, being rehydrated and nourished while the doctors conducted tests to determine what was wrong with him.

The tests showed that Brian had contracted a parasite known as cryptosporidium (crypto for short) that infects thousands of Americans every year. Raw seafood — those oysters on the half shell Brian had passed on — is one source of crypto, but it can also be found in unpasteurized cider, public drinking fountains, and food washed or cooked in contaminated water.

Brian was sent home with a prescription for nitazoxanide to ease his symptoms. But the road to recovery was a bumpy one. He would feel better for a few days, then relapse, then get better, and then end up back in bed.

Frustrated, Brian, who had been my patient for several years, came to see me. An avid cyclist, he had been in excellent health until he became sick. Now Brian was concerned because he was not improving as quickly as he would have liked. He also wanted me to help him determine how he could have become so ill at a luxury four-star resort, even though his wife, Betsy, was perfectly fine. “We ate in the same restaurants and went to the same beaches. Now I’m sicker than I’ve ever been, and there’s nothing at all wrong with Betsy.”

I did a little detective work and called the resort. Long story short, quite a few people had gotten sick at the same time as Brian had, all from swimming in the resort pool, something Betsy skipped. Pools, lakes, Jacuzzis, and hot tubs can all be sources of this parasite, usually from contamination by feces, and chlorine doesn’t have much effect on it. Swallowing just a small amount of water is all it takes to make a person very sick.

As many people with crypto discover, waterborne illness can be just as distressing to deal with as food poisoning. Even in the healthiest people, crypto often seems to go away and then returns, repeating the process for a month and sometimes more. I encouraged Brian to continue his medication and follow my instructions for boosting his immune system. After six weeks or so, he was fully recovered and back to his healthy, active self. Although the resort paid for his treatment, most people aren’t that lucky. That’s why I encourage you to be careful with food and beverages, even water.

Last Updated: August 16, 2018
Originally Published: September 17, 2012