Usually the downfalls of a hike into the woods are mosquitos, ticks and black flies. All fairly noticeable. However, there are those occasions when unpleasant encounters are made unknowingly.

A quick drink from a cold, mountain stream can be refreshing on a hot, summer day. Most of the time there are no ill effects. On the rare occasion though, tiny parasites may be lingering in the water. Some of these parasites are known as giardia.

Giardia causes giardiasis, a diarrheal illness. It is not fatal, but is extremely uncomfortable. The odds of contracting giardiasis here are slim. To be exact, the incidence rate for Boundary County in 2009 was 0.92 persons per 10,000 people. Over the last thirteen years, between nine and thirty-one cases have been reported each year for all of the five northern counties in Idaho.

Giardiasis is more of a threat in undeveloped countries that do not have adequate sanitation facilities. However, it can be contracted wherever giardia lurks, such as lakes, streams, swimming pools or childcare centers. Inadequate hand-washing by an infected person or one caring for an infected person can spread the parasite.

One can become infected with giardiasis by swallowing parasites in water or food that has come into contact with infected feces. Giardia is a parasite that lives in the small intestine and is passed along in feces. It can survive for months outside the body because it resides in an outer shell, called a cyst.

Once ingested, stomach acids trigger the release of the parasite from the cyst. The parasite then moves into the small intestine where it asexually reproduces. As it moves towards the large intestine, the outer shell surrounds the parasite again.

Feces can contain hundreds of millions of cysts, but it only takes 10 to 25 cysts to cause an infection. Sometimes there are no symptoms, but usually the symptoms appear seven to ten days after ingestion and last for two to six weeks. Symptoms include abdominal cramps, diarrhea, increased gas, bloating, fatigue and nausea.

The body can naturally rid itself of the parasites within one to two months, but there are several treatments that will kill giardia in one to two weeks.

Since giardia is not visible, it is impossible to tell if water is contaminated. However, it helps to know how giardia is transferred and its likely hosts. Hosts include small aquatic and semi-aquatic mammals, such as beavers, muskrats and small rodents. Birds and other mammals can also be hosts if they have ingested contaminated water. 

Fortunately, I have only heard accounts of other people having giardiasis and thankfully there are ways to prevent it. First of all, drink water from home or a known, safe source. Secondly, boil water for one minute, filter the water or use chemical purification.

It may not be practical to boil, filter or treat the water you drink from mountain lakes or streams. The chances of ingesting giardia are slim around here but it doesn’t hurt to know about “beaver fever” or “backpacker’s diarrhea” in case you are traveling.

Laura Roady is owner of Roady Outdoor Photography and is a freelance photographer and writer. She can be reached at 267-5397 or roadyphoto@gmail.com