[pct-l] Giardia Myth... or truth?

[Steve Scoles]

The link below is to a comprehensive study of Giardia in the Sierra Nevada.
I have found it to be an excellent resource and debunks a lot of the scary
myths that are propogated about the dangers of drinking the water found
along most of the PCT.  I have drunk freely from most of the water sources
that I have encountered as a hiker over the past 40+ years.  I got sick two
times in my life from drinking trailside water, which I knew was bad when I
drank it.  Of course one has to be wary of agricultural zones and areas with
a lot of human activity.
I just hiked the Washington PCT this summer, and drank unfiltered, untreated
water from about 200 selected sources.  I treated only one ugly source,
Lizard Lake, with a couple of iodine drops per quart.  No problems.

The study is a long read, but very interesting.  A couple of highlights:

"Untreated Sierra Nevada water should be, almost everywhere, safe to
drink—if
you "drink smart."  If you don't "drink smart" you may ingest
diarrhea-causing organisms.  But it won't be Giardia.

Because up to 1 in 14 of us carries the Giardia parasite, we all need to do
what we can to keep the water pure.  Defecate away from water, and bury it
or carry it out.

Camp cooks in particular need to pay special attention to cleanliness.  Wash

hands thoroughly, especially before handling utensils and preparing meals.
If you contract giardiasis in the backcountry, blame your friends…not the
water.

High Sierra water has far too few Giardia cysts for you to contract an
infestation from it. Even if you go somewhere where the concentration is
high, you probably won't get giardiasis. If you do get giardiasis, you
probably won't have any symptoms. If you have symptoms, they will probably
go away by themselves in a week or so. If they don't or you develop serious
persistent symptoms, you should seek medical treatment. Finally, those
contracting giardiasis may develop immunity to it, thus lowering the
likelihood that they will get it again.

There is certainly no reason for anxiety about giardiasis.  Fewer than 1
percent of those who have an infestation, or about 5 percent of those with
symptoms, need medical help.

Recommendation

Our wilderness managers are in a position to educate the outdoor public
about the real culprit in the Giardia lamblia story:  inadequate human
hygiene.  When they acknowledge that Sierra Nevada water has fewer Giardia
cysts than, for example, the municipal water supply of the city of San
Francisco, maybe they will turn their attention to it.

The thrust of the following observation is long overdue:

"Given the casual approach to personal hygiene that characterizes most
backpacking treks, hand washing is likely to be a much more useful
preventative strategy than water disinfection! [††]  This simple expedient,
strictly enforced in health care, child care, and food service settings, is
rarely mentioned in wilderness education materials."

Here is the whole study:

http://www.yosemite.org/naturenotes/Giardia.htm

--Coyote Steve



On Sun, Sep 28, 2008 at 7:52 AM, Timmy Fearn <mountainprana at earthlink.net>wrote:

>
> Hey Ya'll
>
> On a recent trek of the Uinta Highline Trail in Utah my friend mentioned
> that there was a story out there that water tumbling over rocks for 20 feet
> or more would be "pure", anyone out there heard this story or better yet
> have links to more information in direct relation to this story?  I stopped
> treating 99% of my water starting in 1998.  I usually only treat when I go
> with other people because I usually am the only one who owns a filter, and I
> just filter my water as well cause I don't want to deal with the drama of
> trying to justify my position or in case I need to share my water with
> others on that trip for drinking, washing, cooking, etc...  I remember in
> 1998 Brick Robbins posted an excellent article on this list about giardia.
>  One of the things I remember about that article was that they postulated
> that only about 30% of people would have a symptomatic response to giardia.
>  Any science based info born out of an actual study of the subject would be
> greatly appreciated.
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