Re: [pct-l] Giardia, Chlorine and Iodine

[Brick Robbins <brick@fastpack.com>]

At 08:30 AM 8/23/99 -0700, Carolyn M Eddy wrote:
>I've been letting the water sit overnight. 10 minutes was the least
>recommended time on the directions but they said overnight was better.

The 10 minutes is good for most bacteria, but Giardia is tough to kill.

> But, I'm a nurse and we use 10 % bleach solution to kill everything. 

Yep. 10% will kill everything, including the person drinking it.

>Perhaps the CDC can't recommend it because the research hasn't been done?

I included the reference to answer this point, but I guess it wasn't read.
The research has been done, and can be read at
http://www.gorp.com/gorp/health/WTRFLFAQ.HTM 

The basic point is that various factors such as chlorine concentration,
contact time and organic content all interrelate to determine the efficacy
of chlorine against giardia. The interrelationship is complicated and
treatment must be tailored to meet the situation, so one treatment regimen
is not possible. A little complicated for backcountry use.

Don't take my word for it. Read what the CDC had to say.

Another distinct possibility is that you have been exposed but don't
display any symptoms of GIARDIASIS (Giardia infection). There is
considerable evidence that about half of those exposed develop sub-clinical
infections and never know they have it. A good portion of the population
seem to have immune systems strong enough to eliminate the infection all
together. 

I suspect for every hiker like GoForth who gets really sick from the bug,
there is a hiker who never treats the water and never gets sick.

-Brick
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