If you've ever been so cold that your teeth started chattering and your body began to shiver uncontrollably then you've experienced mild hypothermia. Most of us have been there, particularly when we were kids for indeed children are particularly prone to this potentially deadly condition.

Simply put, hypothermia occurs when heat loss from the body outstrips heat production. Even during mild weather hypothermia can occur for outside temperature is just one of a number of factors which contribute to the onset of the condition.

A tired cyclist cruising through the countryside on a fine spring day could be a potential hypothermia victim. If tired, the cyclist's energy reserves are already waning. Being, in all likelihood, sweat-soaked, the cyclist's garments will be sucking heat away from the body at a rate 240 times faster than at the start of the day when presumably the cyclist was dry. Even on a windless day the speed of the cyclist creates its own wind multiplying the rate of heat loss exponentially. Exertion is also contributing to the cyclist's quandary by causing dehydration through sweating and breathing.

Dumb is Dumber

All of these factors working in concert, dehydration and fatigue; outside temperature and dampness could spell disaster. The cyclist's inexperience more than anything else could prove deadly. Ignorance is the number one cause of this number one recreational killer. Armed with knowledge the cyclist can take simple precautions and avoid hypothermia in even its mildest form.

A savvy cyclist will dress in layers, shedding them as body temperature rises, donning them again as it drops. The inside layer will be a thin synthetic such as polypropylene that whisks moisture away from the body. Intermediate, insulative layers will be loose-fitting and made of fleece or wool. A breathable shell made of Gore-Tex will complete the package, acting as a barrier to rain, fog or condensation but at the same time allowing sweat in the form of water vapor to escape. Gloves, possibly in layers, and an insulating helmet liner complete the ensemble of a well-prepared cyclist.

Knowledge will further tell the cyclist that both water and energy will require regular replenishing and by habit the cyclist will frequently consume high-energy foods such as granola bars, trail mix and the like. Such foods contain sugars which provide immediate energy, carbohydrates which release their energy over a moderate period of time and oils and proteins which take the longest to be processed into usable energy by the body. That energy propels the bicycle forward, keeping the cyclist warm at the same time.

The informed cyclist will also recognize that chills and shivering are the earliest signs of hypothermia's onset. The cyclist will know that decision-making will soon become confused and coordination impaired if the condition is allowed to progress. Immediately the cyclist will switch from recreational mode to a survival-bent one, seeking ways to stabilize net heat loss from the body core.

Stumbles, Fumbles, Mumbles and Grumbles

If hypothermia progresses our cyclist must rely on companions to correctly assess the situation. The inexperienced may fail to notice the violent shivering, slurred speech, clumsiness, even irrationality that indicate their buddy is already suffering from moderate hypothermia. If they fail to intervene and the body core temperature of the victim continues to drop then unconsciousness, coma and finally death, all consequences of late-stage hypothermia, can be expected.

Treatment protocols of moderate to advanced hypothermia are complex and ever-changing. In the normal course of things, when adequate preparation and prevention measures are strictly adhered to, no one should ever get beyond the initial symptoms. Accidents do happen, however and a kayak spill in the west coast surf or a slip into an icy creek while hiking could be just the kind of event to precipitate the rapid onslaught of life-threatening hypothermia. The Wet Coast of British Columbia is aptly nicknamed because the conditions which prevail on Canada's west coast are ideal for hypothermia. Anyone, even casual recreationalists, who venture into the wilderness should consider taking a wilderness first-aid course which includes training in hypothermia prevention and treatment. Slipstream Wilderness First Aid offers regular, certified training at many levels of proficiency geared specifically for outdoor recreational settings.

The End

All the guide books tell you to boil, filter and chemically treat all water and I will too just to cover my butt in the event of liability issues. I always disregard this good advice, drinking directly from the stream, and thus far have never been sick. If you choose to enjoy the taste of unadulterated stream water too then you did so of your own volition. If the water made you sick then it’s your fault and not the fault of this book or the bear which crapped upstream.

Whatever your choice is get your water from clear running brooks not from lakes or ponds. Water from snow pack is better than water from glaciers. The latter contains too much clay. Carry lots of water, at least 40 litres, whenever kayaking as good water can be surprisingly hard to find on the wet coast of Canada. A green algae bloom in tide pools or wet patches trickling across a beach does not mean something horrible died in the water. It just means the water is brackish. Freshwater will be found up the slope.


Giardia cysts can exist under the most pristine, wilderness conditions. Clear running water is not a sure sign that it is drinkable.

Illustration by Manami Kimura

If your source of water is at a popular camping spot then go upstream away from the camp to get your drinking water. Take great pains to clean yourself and your dishes or clothing well away from the bank of any water body or the water will become polluted. Leftover food does not belong in the water. If fires are allowed and it is safe to do so, burn it. Try to avoid using soaps or detergents but when you must only use the biodegradable kind available from outdoor stores.

Fevered Beavers

Beavers have gotten a bad rap, taking most of the blame for spreading a disease that can just as easily be passed into the water system by deer, muskrats, raccoons, coyotes and squirrels. Indeed any mammal including domestic pets, livestock and humans are guilty of carrying the protozoan parasite into the backcountry.

Giardia lambia, as the microbe is called, enters the environment in hardy cyst form where it can survive for weeks at a time. Giardia cysts can exist under the most pristine, wilderness conditions. Clear running water is not a sure sign that it is drinkable. Ingestation of a single cyst is enough to cause infection in humans. The hard, capsule-like shell dissolves, releasing the infectious form of the parasite which multiplies exponentially.

Full-blown giardiasis may take from 5 to 25 days to manifest itself though symptoms typically appear within 10 days. The giardia protozoa latch themselves on to the intestinal tract, severely impairing the body's ability to absorb nutrients and water. Food and water pass straight through the digestive system instead, appearing as the principal symptom of giardiasis, diarrhea. Infection usually lasts for around two weeks and is usually treated with antibiotics though some individuals may never show symptoms at all and others recover without treatment. Giardiasis has been known to persist for months on end in those with weakened immune systems.

The best treatment of course is prevention and prevention typically means water purification. The surest method of water treatment is boiling. Five minutes at a steady boil will destroy every living organism in the water. Additional time is needed at higher elevations. Boiled water can be bland and dull tasting. Shaking oxygen back into it will help improve the taste.

Expensive, heavy filters are available which claim to strain out giardia lambia. Studies have shown however that not all filters are effective. In order to effectively purify water the filter porousness must be no bigger than 0.2 microns. Such fine filters are hard to pump but produce great tasting water. Chlorine-based water treatments are not effective against giardia cysts. Iodine treatments fare better but studies have shown that a typical 20 minute treatment is not enough to eliminate all cysts. Eight hours is the minimum required for effective iodine treatment. Iodized water tastes horrible however and in rare cases may cause thyroid problems.

The End

Notable Quotes

...a frank, sensibly written and slightly political guide...

-- Tom Zillich; The Westender