Dehydration - Giardia
The low humidity and high winds common at high elevations can quickly dry out your body. Dehydration can increase your risk of fatigue, hypothermia, and altitude sickness. Drinking plenty of water is the best protection against dehydration. If you are hiking in Rocky, plan on taking about 1 quart or liter of water per hour of your hike. More if you are climbing or backpacking.
Giardia is a parasitic protozoan found throughout the park in lakes, streams, and possibly snow. It also lives in the digestive systems of wildlife, livestock and humans. Humans introduced giardia to the park. The local wildlife is not affected by the parasite but when infected, they refer to it as "the human disease."
In cyst form, giardia enters the surface water when animals or humans defecate in or near the water. Within one or two weeks after ingestion, giardia can cause diarrhea, cramps, bloating and weight loss. Giardiasis requires treatment by a physician.
To prevent giardiasis, boil all untreated water for three to five minutes to kill the giardia cysts and other harmful microorganisms.
If you suspect infection, seek medical treatment by a physician.