With snow and bugs gone from the high country, the cool days of autumn bring out the backpackers and climbers like no other time of year.
It is also, unfortunately, as likely a season as any to catch a dose of Giardiasis, better known as beaver fever.
More than 2.5 million North Americans are infected every year by Giardia lamblia, the tiny parasite that causes the infection. The majority of those people are outdoors enthusiasts, and nearly all the cases come from drinking untreated water.
Beaver fever is actually a bit of a misnomer because any mammal, humans and livestock included, can act as a reservoir for G. lamblia and pass it on in feces, either directly into water or onto land, where it is carried by runoff into lakes and streams. Once there, the parasitic cysts can survive for months.
In your gut, G. lamblia releases organisms called trophozoites that attach themselves by a sucker on their bellies to the wall of the small intestine.
Multiplying rapidly, they form colonies so dense as to inhibit the transmission of nutrients from food into your body. Weight loss and anorexia can result.
Sound ugly? Well, so are the symptoms. Within one-two weeks you can develop any or all of abdominal cramps, diarrhea, vomiting, bloating, foul breath and fever.
Typically, after three or four days, these symptoms will diminish, only to reoccur in many cases for months or even years, weakening the constitution over time, so that you become vulnerable to a range of chronic diseases. Children are particularly at risk.
Diagnosis - by examining the stool for cysts - is relatively straightforward, though treatment is not. A number of different antibiotics are used against beaver fever, though all have side effects and some will attack only the trophozoite stage, leaving the cysts unharmed.
Moreover, resistant strains of G. lamblia have been appearing for some time now, immune to most if not all available drugs. There is presently no vaccine for the parasite.
On the bright side, many people who contract beaver fever exhibit the symptoms for a few days and then apparently throw it off for good, simply on the resources of their own immune system.
You can aid this process with anti-parasitic herbs such as black walnut, cloves, wormwood, garlic and pumpkin seeds. Take vitamins A, B, C, plus minerals zinc and calcium, preferably through intra-venous therapy, in order to by-pass your digestive system, which is compromised by beaver fever.
If you are on antibiotics, be sure to take probiotics, the "good" bacteria that strengthen the flora in your gut. Also, limit your consumption of sugar. It feeds the parasite.
Finally, if you're a traveller, bear in mind that 20 to 30 per cent of the population in developing countries are infected with G. lamblia because of poor hygiene.
The usual rules apply: wash your hands frequently, drink only purified water and don't eat anything that isn't thoroughly cooked.