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#21377 - 06/21/06 01:48 PM Re: Genetic drift... [Re: irisharehere]
D75 Offline
enthusiast

Registered: 03/18/05
Posts: 293
Loc: Holiday Inn Express
Quote:

Oh yeah - bacteria on the sidewalk - turns out that paving stones exposed to UV all day are actually a really harsh environment........




So is that your education speaking, or did you actually fail to get a culture?

What's next?

Burying waste x inches deep y feet from water, or smearing it into a thin layer on a rock that is exposed to sunlight and inaccessible to the animals that might eat it? (Assuming that packing it out is not an option, of course.)

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#21378 - 06/21/06 01:51 PM Re: Genetic drift... [Re: irisharehere]
Chas Offline
Pooh-Bah

Registered: 03/22/01
Posts: 1754
Loc: Flagstaff
As for why are doses in nice round numbers. I can answer that since I've set up dosing strategies for combination products (products that contain both pharmceutical agents and devices).

1) when you set up a dosing strategy in general you start out with cell culture work and you establish the minimum therapeutic dose and the toxic limit, which in some drugs can span a couple orders or magnitude and for some its very tight.

2) you then go into a preclinical model ( and establish safety and efficacy in a model that most closely represents conditions in humans).

3) You pick an dose that shows both safety and efficacy in the preclinical model and then after a few years of diligence on the part of a significant team of people you then show safety in a clinical study. (Phase I)

4) In a Phase II clinical study you show dose dependency. And why nice round numbers, because of human nature. In most drugs the variability between individuals (or any biological systems) will vary enough that you would never show a difference between a 250ug dose and a 256ug dose. So why go with a 250ug dose. Its easier for people who are working with it.

For the drugs I work with (strong antiproliferatives) - given data from my field, since I work with research and there is confidentiality and also since its an R&D device, I am also covered by FDA yada, yada, yada....,, (and since I work with devices my dosage is given in ug/mm and actually also as a release rate which is given as a diffusion constant based on first order kinetics but I'll keep it simple here) but we see minimum variation between 5ug/mm and 20ug/mm. You keep it simple and choose round values and not 10.16ug/mm.

What I described above is a very simplistic explaination which involves years of work... but the rational is applied.


As for me calling D75 a moron (sorry for not being PC but thats it), he gives general statements not needing to treat water. Maybe from the pipe at the Trapps you don't but if you go to a stream or a lake in the Cascades (friend Adam got giardia there) the Sierras (I got giardia there) Peru (hugo was doubled over there) Nepal (about 3/4 of the people on the permit I was on there ended up on Ciprofloxin since there bowels were ready to explode) it just doesn't hold water (no pun intended). No you won't die, but for 3wks you only wish you were. Will you get it every time, of course not, but when you do.... you'll remember it for quite a while. Use your discretion. If you don't want to filter, fine- its your decision. If you want to filter- no one should chide you for it.

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#21379 - 06/21/06 02:56 PM Re: Genetic drift... [Re: Chas]
paulraphael Offline
enthusiast

Registered: 01/22/02
Posts: 321
Loc: New York, NY
Question ...

Before the mid '80s or so, most outdoors people presumed mountain stream water in this country to be safe, if it met a certain number of criteria (distance from trails, roads, livestock, etc; flowing swiftly, exposure to sun ....)

Everyone i knew drank right out of the creeks and I never saw anyone get sick. This included a month-long backpacking trip in the Absarokas with over a dozen other people, and many summers in the Tetons, Gros Ventre, and Front Range.

Then, almost overnight, there was news that the water should be presumed unsafe. There was clinical evidence, and also what seemed like an overnight emergence of people I meet who'd had giardia.

The explanation I heard is that this wasn't an information epidemic, but a real one ... that somehow, a cycle that included people but was mostly perpetuated by livestock and high mountain voles, had spread giardia throughout most of the surface water on the continent.

Does anyone know anything about this? I'm still curious about the real story.

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#21380 - 06/21/06 05:30 PM Re: Genetic drift... [Re: paulraphael]
D75 Offline
enthusiast

Registered: 03/18/05
Posts: 293
Loc: Holiday Inn Express
Start here. CDC stuff. A bit old. Ends in 2002.

Note higher incidence in young children <10 yrs. and middle aged adults. Note also that mandatory reporting was started in 2002. Oddly even though many sources were identified, community drinking water, swimming pools, day care centers, diaper changing, etc., no real attempt was made to categorized incidences by source. Closest you get is by US state.

Worst state is VT with over 20 cases / 100,000 population / year. Lowest TX, with less than 1 / 100,000.

Do not see anything here that would really help to quantify the risk (probability). I.e. given that you drank from a random Sierra source, the probability of your becoming infected.

Boiling and filtering are the recommendations. Specific filter size requirement listed. Halogenation results depend on pH, clarity, ... Effectiveness of UV would certainly depend on clarity as well.

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#21381 - 06/21/06 06:14 PM Re: Genetic drift... [Re: D75]
irisharehere Offline
Site Supporter

Registered: 12/06/01
Posts: 1658
Loc: Danbury CT
A study from sereral years back reported that of packstock surveyed at 17 commercial or government operations in the Sierra Nevada range, roughly 5% were shedding Giardia duodenalis cysts at the time of investigation.

That would make me want to treat my water out there!

I'll do some more nosing around PubMed tonight, see whats out there......
_________________________
I didn't spend nine years in Evil Graduate School to be called "Mr Irish", thank you!

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#21382 - 06/21/06 07:41 PM Re: Genetic drift... [Re: irisharehere]
MarcC Offline
Carpal Tunnel

Registered: 07/10/00
Posts: 3532
Here we are hammering away on giardia and all the OP wanted to know was if the SteriPen was worth the cost and how well it works!

Giving D75 a bone (merciless troll that he is!), it's true that in the high Sierra, you probably won't get giardia from drinking untreated water, and, the "dangers of giardia" has likely been quite a bit over-hyped. These two articles are a pretty rational take on the subject:

http://lomaprieta.sierraclub.org/pcs/articles/giardia.asp

http://www.pcta.org/help/join/magazines/SierraWater.asp

However, D75 and anyone else who insists treatment isn't necessary might want to consider.....

OK, so you probably won't get giardia unless you're taking water from streams below pastures, heavily used camp sites, and subject to run-off from pack trails. Do you know for sure your pristine stream isn't one of the risky ones? Since giardia can manifest in as little as one week, would you put 2/3s of your planned 3-week backcountry trip in jeopardy for the sake of saving a few ounces in your pack?

Alright, let's ignore giardia. What about cryptosporidium, yersinia, salmonella, campylobacter, aeromonas, other fecal coliforms, and E. coli (particularly strain O157:H7, which has been fatal in otherwise healthy, non-immunocompromised adults)?

As another poster said, it's up to you. You buys your ticket and takes your chances, but I wouldn't want to have to depend on you as my partner on such a trip.


Edited by MarcC (06/21/06 07:50 PM)
_________________________
- Marc

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#21383 - 06/21/06 10:22 PM Re: Genetic drift... [Re: MarcC]
chip Offline
Carpal Tunnel

Registered: 10/06/01
Posts: 2676
Loc: Sittin' Pretty in Fat City
My sister-in-law, the veterinarian, says that there are big problems right now with domestic animals becoming infected from drinking in streams. Seems the culprit is bacteria from deer urine. You just never know.
I've drunk heartily from many streams and rivers, including in Little Yosemite, without filtering or problems. I've also twice gotten the "revenge" in Mexico. while the weight loss is significant, it put a hefty dent in my activities for a bit.

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#21384 - 06/21/06 10:31 PM Re: Genetic drift... [Re: MarcC]
D75 Offline
enthusiast

Registered: 03/18/05
Posts: 293
Loc: Holiday Inn Express
MarcC,

thanks for injecting some real science into this thread. My take after reading the two articles would be that not only will you "probably not get a giardia infection from drinking Sierra water", but that in fact it is extremely unlikely, far less likely even than I imagined when I first labelled the concern paranoid.

I hope others who are so paranoid about their water will read the articles in their entirety.
  • Are we shocked that the city of SF water supply is more contaminated than the Sierras?
  • After reading the articles, it makes perfect sense.

What can we take away from this "troll"
  • Popular sources for science information is often outright wrong. Yet this is the source that the public relies on.
  • Even scientists often believe the information, if it is not directly in their field of study.
  • Our own personal background may leave us with a view that is perceived to be correct, and we will hold tenaciously to that, even in the face of contrary data - aka confirmation bias.
  • Manufacturers, and others, often have profit motives associated with fear, and will exploit that fear.
  • Simply questioning the data or logic, can result in discovery. In this case, I simply based my questions on experience contrary to claims, as well as the known fact that humans have been drinking these same water sources for ages.

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#21385 - 06/22/06 01:48 AM Re: Genetic drift... [Re: D75]
Mike Rawdon Offline

Carpal Tunnel

Registered: 11/29/99
Posts: 4276
Loc: Poughkeepsie
Quote:

Manufacturers, and others, often have profit motives associated with fear, and will exploit that fear.




I was waiting for this to come up. It seems to me the fears associated with backcountry water are closely aligned in time with the emergence onto the market of small water filters.

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#21386 - 06/22/06 02:25 PM Re: Genetic drift... [Re: Mike Rawdon]
Chas Offline
Pooh-Bah

Registered: 03/22/01
Posts: 1754
Loc: Flagstaff
The only thing the article didn't address (which was a well written article but only recognizes one source, while not considering other sources including bacterial or viral sources). It also doesn't address concentrations in a water bottle, which makes for a great incubator.

As I say, do what you wish. But if you ever travel with me, damn straight that you'll be drinking treated water, since I've had more then one climb ruined with partners doubled over. My last trip to Peru, we sat out a snow storm with my partner spraying shit on everything around him (drinking out of a stream contaminated with cow feces) and meant he was too weak to attempt the first one day ascent of the Peruvian route on Cayesh (heck, eay to be the first one day ascent when its the second ascent) and was too weak to attempt the Paragot Route on the North Face of Huascaran Norte, which meant I spent the trip waiting for him to get his strength back.(and yes, he did did see a doctor to have the exact type identified). He now filters and treats everything.

Yes, in other countries, giardia is not the culprit which is why Ciprofloxin is often used as a treatment (which is a broad spectrum gram positive/gram negative antibiotic). Yes, some of us, travel to other countries on a regular basis for climbing (so far this year I've already been to Nepal and South America) and treating becomes far more important.





Edited by Chas (06/22/06 02:32 PM)

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