A reason to prefer UV over filters in North America?

[Stephen Barber]

It has been repeatedly said that backpackers do not need to be concerned with viruses in North American waters. While the effect is not catastrophic, a 10% loss of cognitive function is disturbing.

Popular description: http://finance.yahoo.com/news/virus-found-lakes-may-literally-145000290.html

Peer reviewed synopsis: http://www.pnas.org/content/early/2014/10/23/1418895111

[Evan Chaney]

Interesting read. I have been looking into more uh than the drops.

[Greg Mihalik]

Interesting indeed.

In the human analysis n=92 and incidence = 40
No mention is made of the exposure route.

In the mouse study "… We found detectable antibodies to ATCV-1 by enzyme immunoassay (ELISA) in 10 of the 28 mice exposed to ATCV-1"

n=10 is pretty small

I'll wait for a collaborating study.

[Bob Gross]

Each of the different forms of water treatment have a completely different effect on organisms in the water. Some are more effective than others.

You really, really, need to assess what the likely threats are in the raw water where you travel, and then choose your treatment method accordingly.

Too many of these lousy scientific articles are written about water sources a thousand miles from where you travel, and they may have zero relevance to the water that you find.

I've traveled in Nepal, and the raw river water is some of the worst that I have had to use. It starts as glacier melt, but it gets contaminated by raw sewage from upstream villages. As a result, boiling the water is almost required to kill viruses.

I've traveled a lot in California's Sierra Nevada, and the typical streams there are thought to have nothing worse than Giardia. That can be easily snagged by a filter for low-tech treatment.

In other places, you have different risks. Choose your treatment tools carefully. Then decide your course of action if the primary treatment fails (e.g. the battery goes dead in your UV light).

–B.G.–

[Rex Sanders]

+1 on Greg's comment: The numbers for both mice and humans are way too small to make sweeping generalizations.

And somehow the researchers adjusted for "age, sex, race, educational level, maternal education, cigarette smoking, and place of birth" with n = 40 virus-positive individuals.

Skeptical.

Wait for a better study.

— Rex

[Roger Caffin]

> I'll wait for a collaborating study.
Understandable, but possibly misguided.

In another experiment, conducted to test the hypothesis that a Colt 45 was dangerous, it was found that 2 out of the 3 people in the experiment who put a bullet in their head died. The 3rd person managed to put the bullet through the frontal cortex and did not die; they just lost all sense of ethics or judgement.

However, since 3 people is far too small a number to form any valid statistical judgement, it was decided that the results were not meaningful.

Yeah, right.

Cheers

[Eric Blumensaadt]

I use a Steripen Adventurer for my bike bottle (carried in a front pouch) and Katadyn Micropur chlorine dioxide tablets for my hydration bladder.

The Steripen is fast for the times I need to refill my bike bottle too make more electrolyte drink like Cytomax. The Micropur tabs are also a backup. Both kill viruses and thus are EPA classified as water PURIFICATION items.

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