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olyclimber

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From the CDC (when talking about natural disasters):

 

Boiling water, when practical, is the preferred way to kill harmful bacteria and parasites. Bringing water to a rolling boil for 1 minute will kill most organisms. Boiling will not remove chemical contaminants. If you suspect or are informed that water is contaminated with chemicals, seek another source of water, such as bottled water.

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Olympia Climber: The answer is I don't know for sure.

 

Some bacterial cysts can survive in some pretty crazy environments (absolute zero temps, high radiation, vacuum, etc), but most of those probably aren't pathogenic.

 

I've only felt the need to boil water for the sake of hygenie a few times and I felt that just getting the water to the boiling point was good enough.

 

HERE is some actual data about survival rates of various pathogens I found on teh interweb.

 

Relevant excerpt:

The chart below indicates the temperatures at which the most common waterborne pathogens are rapidly killed, thus resulting in at least 90 percent of the microbes becoming inactivated in one minute at the given temperature. (The 90 percent reduction is an indicator frequently used to express the heat sensitivity of various microbes.) Thus, five minutes at this temperature would cause at least a 99.999 percent (5 log) reduction in viable microbes capable of causing disease.

 

 

 

 

Microbe Killed Rapidly At

Worms, Protozoa cysts (Giardia, Cryptosporidium, Entamoeba) 55°C (131°F)

Bacteria (V. cholerae, E. coli, Shigella, Salmonella typhi), Rotavirus 60°C (140°F)

Hepatitis A virus 65°C (149°F)

(Significant inactivation of these microbes actually starts at about 5°C (9°F) below these temperatures, although it may take a couple of minutes at the lower temperature to obtain 90 percent inactivation.)

 

 

 

 

 

 

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I'll write a grant for a water quality survey of Cascade Mountain surface waters and see if I can get it funded.

 

Since all of ~20 people (my guess) contract water-borne illnesses from backcountry sources in all of WA state/year, with zero deaths, I'm sure it will be a major priority for the DOH.

 

LINK to Ivan's story about campylobacter infection in the enchantments.

 

LINK to good info.

 

 

PREVIOIUS thread about giardia

 

A quote from THIS THREAD :

 

I took the time to read this article throughly, and it really presents a good discussion of giardia and other microbes in the back country. I thought it deserved being highlighted a bit better.

 

Giardia Lamblia and Giardiasis With Particular Attention to the Sierra Nevada By Robert L. Rockwell, PhD

 

(the following quote by no means summarizes the entire article, but seems germane to the discussion here)

 

"Also, while so much attention is being given to Giardia, there are worse organisms to worry about such as Campylobacter, Cryptosporidium, E. coli, and the other organisms mentioned earlier.

 

In an informative study, [37] investigators contacted thousands of visitors to one of the high-use sites during the summers of 1988 through 1990. Water samples taken on 10 different dates at each of three locations exhibited Giardia cyst concentrations between 0 and 0.062 (average 0.009) per liter. A goal was to enlist volunteers who were cyst-negative before their trip, verified by stool analysis, and then determine what fraction were cyst carriers after the trip. Unfortunately, stool collection is not a particularly enjoyable task, and only 41 people agreed to participate. Of these, two acquired Giardia cysts during their trip, but neither came down with symptoms. Six of the others exhibited post-visit intestinal symptoms, but none tested positive for Giardia (interestingly, all six had filtered their water). In sum, no cases of laboratory-confirmed symptomatic giardiasis were found.

 

The water that wilderness travelers are apt to drink, assuming that they use a little care, seems almost universally safe as far as Giardia is concerned. The study referred to earlier,2 in which the researchers concluded that the risk of contracting giardiasis in the wilderness is similar to that of a shark attack, is telling. What they did find is that Giardia and other intestinal bugs are for the most part spread by direct fecal-oral or food-borne transmission, not by contaminated drinking water. Since personal hygiene often takes a backseat when camping, the possibility of contracting giardiasis from someone in your own party—someone who is asymptomatic, probably—is real. Recalling that up to 7 percent of Americans, or 1 in 14, are infected, it is not surprising that wilderness visitors can indeed come home with a case of giardiasis contracted not from the water…but from one of their friends.

 

This theme, that reduced attention to personal hygiene is an important factor for contracting giardiasis in the wilderness, is becoming more frequent in the literature.2, 10, 14, 37, [38]

 

Outside of the Sierra, Giardia cysts in concentrations “as high as four per gallon [§]” have been detected in untreated water in northeastern and western states. [39] But even with this concentration, one would have to consume over nine liters of water to have a 50 percent chance of ingesting 10 or more cysts.

 

Indeed, there may be as much unwarranted hysteria surrounding Giardia in wilderness water in these other areas as there is for the Sierra. For example, an oft-cited report describing acquisition of the disease by 65 percent of a group of students hiking in the Uinta Mountains of Utah [40] is now viewed with considerable skepticism. Specifically, the attack rate was far beyond that usually seen with water-contracted giardiasis, no cysts were identified in the suspect water, there was no association between water consumption rates and the likelihood of the disease, and the authors categorically discounted food-borne or fecal-oral spread, stating that it had never been reported (correct at the time).2 "

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