Go ahead and take a drink. I dare you. You will be on Tahosa's weight loss program in about 24 hours, and don't squeeze the Charmin. Beaver fever has been around a long time and it’s not to be taken lightly. Even though the cases have dropped over the last few years, all it takes is one sip in the wrong place and get ready to turn your brown eyes blue.

Either pack enough water with you, or take a filter. But before you even venture out, read a map to see if there are any water sources where you are going, and still carry extra water. Those water holes can dry up, and you'll be up the dry creek without a paddle. Okay, we all know we have to wash our hands after using the toilet, but what do we do while we are on a trail some place in the back country? There are those little bottles of hand sanitizer, which work real well, especially if you apply, rinse the appendages, and apply again. And yes, that mountain stream sure looks cool and inviting. And as the Coors commercial says, “It’s the water.” But no one says where the deer went, and where that other backpacker camped last night. Practice the same hygiene on the trail as you do at home, as much as possible.

Beaver fever, or backpacker’s diarrhea, are names used to describe infection with the protozoan parasite, Giardia lamblia. Found in two forms, both as an active trophozoite and as a dormant cyst, Giardia is responsible for making tens of thousands of people sick each year in the United States. Although infection by drinking untreated water is one of the most common causes of Giardiasis, Giardia is a growing health hazard in our treated water supplies and is reaching an epidemic level in daycare centers.

The good news is that a run-in with Giardia in developed areas of the world isn't going to be fatal as long as you are in good health and have access to medical treatment. In more remote sections of Asia, Africa, and Latin America, Giardia is responsible for over two million infections annually and thousands of deaths. Sadly, most of these are children. Knowing this now, if during the last time you were in the great outdoors you gulped down some cool, clean water from a stream, don't panic. Your odds of contracting Giardiasis (a Giardia infection) are extremely low when compared to your odds of slipping in the bathtub or getting into a car accident.

The parasite lives in the external environment in a cyst form. Once ingested, it emerges in the small intestines as a trophozoite. Here, the parasite causes the symptoms of gastrointestinal illness. As the trophozoites pass through the intestines and enter the colon they reform cysts and eventually exit the body as infective cysts. Because the cysts are shed in the feces of infected individuals, transmission of the parasite occurs from ingesting fecally contaminated food or water. This contamination occurs from environmental sources such as wilderness rivers, lakes or streams or from person-to-person contact via the fecal-oral route.

The incubation period of Giardia is 6-15 days, after which, symptoms begin to appear. Infection can be completely asymptomatic, or more likely it is characterized by explosive, watery, foul-smelling diarrhea combined with abdominal cramps, bloating, fatigue, weight loss, flatulence, nausea and loss of appetite.

Diagnosis relies on direct visualization of the organisms (either cysts or trophozoites) in stool specimens. Multiple stool specimens may be necessary since the excretion of the parasite may be erratic. There are also newer enzyme-linked immunosorbent assay (ELISA) techniques that are effective.

Although Giardiasis may be resolved on its own, symptoms can last 2-6 weeks or even longer. Thus, if Giardiasis is suspected, it is recommended to see a physician immediately. The medication most often used in the United States is Nitroimidazole or Metronidazole (Flagyl). Tinidazole is another medication that is popular in other parts of the world. All of the medications are more than 90% effective.

Preventive measures recommended by the Centers for Disease Control and Prevention to avoid infection by Giardia or other waterborne pathogens include: