Bugged by Bad Water on the Trail? Try Treating It

During a Grand Canyon rafting trip, Cliff Sharpe and his buddies always filtered and purified the Colorado River water before drinking it.

Well, almost always. At one point, Sharpe recalls, “a stream was coming out of a wall of rock.” He and his friends assumed the water had been filtered through layer after layer of rock and therefore was pure. So they drank it without treating it.

Not long after, one of the group got sick with cramps and diarrhea. Later, a park ranger said that cattle grazed on top of a ridge near the stream they thought was so pure. Sharpe figures the untreated water was what had sickened his friend, even though the others somehow escaped the misery.

Sharpe should have known better than to trust the water, as he’s the first to point out. He is a water quality engineer and chief of field operations in the drinking water division of the California Department of Health Services.

He tells the story on himself to illustrate that even the most careful outdoor veteran can trip up.

If you’re uncertain about the origin of water in the wild, Sharpe cautions, filter it and treat it chemically, or boil it for one minute.

Hikers and other outdoor enthusiasts who drink untreated water from streams and rivers risk taking in a host of bacteria, viruses and other bad bugs. The bugs most often mentioned by the experts are a couple of nasty parasites called Giardia lamblia and Cryptosporidium parvum. Both are protozoa that can cause diarrhea, sometimes severe.

Giardiasis can last two weeks or even become a chronic intestinal infection. Intestinal cryptosporidiosis can persist for a week or so.

It is impossible to pinpoint specific “hot spots” for either of the organisms, says Dennis Juranek, associate director of the federal Centers for Disease Control and Prevention’s division of parasitic disease. Both are extremely common in bodies of water.

Cryptosporidiosis can occur two to 10 days after drinking tainted water. Giardiasis may not show up for one to two weeks. Both infections can be diagnosed with lab tests of stool samples.

Cryptosporidiosis usually goes away on its own with time. “We don’t have a drug to treat it effectively,” Juranek says. But it can be dangerous in people with compromised immune systems, such as those with AIDS or who have recently undergone chemotherapy or an organ transplant.

Giardiasis, also diagnosed by lab testing of stool specimens, is often treated with metronidazole (Flagyl).

Prevention is simpler. If you’re bound for back-country hiking or camping, take bottled water or purifiers such as iodine tablets or filters--or both. Or boil it.

When buying a water filter--they’re widely sold at sporting goods stores--look for a model with a pore size of one micron or less. “One micron is needed to kill cryptosporidium, and will also easily kill giardia,” which is three times bigger, Juranek says. But one-micron filters might not kill some viruses, so he advises chemical treatment as well.

In lieu of filtering and chemically treating water, boiling water for one minute kills giardia, cryptosporidium and bacteria, even at high altitude, Juranek says. But if you’re worried about the altitude, boil water for three minutes.

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Lyme disease alert: Now that LYMErix, the first vaccine against Lyme disease, is on the market, who should consider taking it to reduce the risk of contracting the bacterial infection spread by ticks?

The Centers for Disease Control and Prevention is expected to recommend next month that the vaccine be considered by people who spend frequent or prolonged time outdoors in areas where the disease-carrying ticks are endemic. But the vaccine will be available too late to give full protection for this season. The manufacturer recommends three doses of the vaccine over a one-year period, with the final dose several weeks before the tick season opens in April.

Lyme disease is concentrated in the Northeast and North Central U.S. and, to a lesser extent, in the coastal regions of Northern California, the CDC reports. See its Web page: https://www.cdc.gov.

The Healthy Traveler appears the second and fourth Sunday of the month.