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Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Re: Re: Re: Re: Re: Re: POP QUIZ probably wrong on 11/03/2013 08:42:12 MST Print View

"Not arguing."

Roger, I think you are just trying to be self-moderating.

--B.G.--

Mike W
(skopeo) - F - M

Locale: British Columbia
giardiasis on 11/03/2013 11:03:25 MST Print View

>> Published reports of confirmed giardiasis among outdoor recreationists clearly demonstrate a high incidence among this population <<

I think this statement just confirms my point, that what is reported by an infected person is often not correct and only serves to skew the data. Just because you have giardiasis and were in the back country doesn't me you got it from a wild water source but that's the first question your doctor will ask you (were you drinking from untreated water sources in the back country). There is no way of knowing if the wild water was the source of the infection or if the suspect water was effectively treated by the hiker.

From a lengthy Ontario (Canada) study:

"The most frequently reported probable risk settings were the home (40.1%) and travel (39.1%). The study findings suggest that a high proportion of cases occur in urban areas..."

The highest infection group is children, who have double the rate of infection as adults, and they are not being infected by drinking wild water in the back-country.

M B
(livingontheroad) - M
sickness on 11/03/2013 11:20:58 MST Print View

Have you noticed that some people will religiously filter or treat water?

But then same people dont give a second thought to rinsing socks or clothing out, soaking feet, taking sponge bath, rinsing hands, face, swimming, etc.

Any contact with contaminated water could be a way for cysts to find its way onto your hands, and into your mouth.


But still, it seems more anecdotally common I think for those that dont treat water, to get sick than for those that do.

Franco Darioli
(Franco) - M

Locale: Melbourne
Poop quiz on 11/03/2013 13:25:29 MST Print View

Bob,
Aussie :not arguing
New American : this

"this" happens to be my pet hate right now...

Susan D
(susand) - M

Locale: montana
Everyone does NOT have giardia on 11/03/2013 14:19:07 MST Print View

>>Everyone has some stran of giardia in them. You are just immuned to "your" stran"

I might have missed it, but no one has corrected this bit of misinformation. Everyone does NOT have giardia. Mayo Clinic: "Some people with giardia infection never develop signs or symptoms but still carry the parasite and can spread it to others through their stool." Maybe you are thinking of this? Certainly, this isn't the majority of people.

Also, you don't give yourself giardia (auto inoculation), as seemed to be implied earlier in the thread.

Ken Thompson
(kthompson) - MLife
Re: POP QUIZ probably wrong on 11/03/2013 14:27:10 MST Print View

Strain not stran

Franco Darioli
(Franco) - M

Locale: Melbourne
POP QUIZ on 11/03/2013 14:40:18 MST Print View

"Also, you don't give yourself giardia (auto inoculation), as seemed to be implied earlier in the thread."
I might have inadvertently done that.
My comments were about sharing rather than self administration.

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: POP QUIZ on 11/03/2013 15:09:35 MST Print View

I'm missing something here...

Is there a suggestion that one can have non-symptomatic giardia in the gut, and through less-than-ideal hygiene habits, introduce giardia orally, and then become symptomatic?

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: POP QUIZ probably wrong on 11/03/2013 15:28:27 MST Print View

Hi Bob

> "Not arguing."
> Roger, I think you are just trying to be self-moderating.
No, I was agreeing with you!

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: POP QUIZ on 11/03/2013 15:33:33 MST Print View

Hi Greg

> Is there a suggestion that one can have non-symptomatic giardia in the gut,
Yes, it happens. A sort of balance is reached with limited harm.

>through less-than-ideal hygiene habits, introduce giardia orally, and then become symptomatic?
Very doubtful, imho.
Giardia is an 'infection' of the intestines. The cysts are excreted. If you reintroduce the cysts from your intestines back into your intestines, there is no reason for you to become suddenly susceptible.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Giardia in the backcountry on 11/03/2013 15:36:59 MST Print View

Hi Buck

> There's a reason physicians often ask "Have you been camping? Did you drink any
> untreated water?"

The reason may be that they learnt this question in med school. Nothing more. Just following rote learning.

The number of people who get giardia from kids at play school is KNOWN to be huge. The number of people who report suspected giardia after going backpacking is tiny in comparison.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: All of the above. on 11/03/2013 15:43:58 MST Print View

> Let''s take it as fact that Giardia can pass through the nose to infect.
Why????
Frankly, I think it is a rather silly idea. It has no realistic mechanism.

> As a solo hiker, many of the potential human related causes go away.
Some do go away of course, but the biggest ones remain: lack of personal hygiene and contaminated water.

Cheers

Jennifer Mitol
(Jenmitol) - M

Locale: In my dreams....
Why is there so much doubt about surface water contamination?? on 11/03/2013 16:59:50 MST Print View

Here's a nice 5-yr study published in the peer-reviewed journal Wilderness and Environmental Medicine that examined water sources throughout the Sierra...a place frequently cited as spore-free (or nearly so).

My first trip to the Sierra in August was for the JMT...and wow did I see a lot of pack animals. And according to this study, just shy of cattle it was the most common area to have giardiasis contamination. It's an interesting read...

http://www.ericjlee.com/Articles/Sierra%20Water%205years.pdf

And not meaning to bring up an old argument, but seriously - does anyone have any good scientific, peer-reviewed data that says drinking untreated surface water in the wild is NOT a risk for giardia?

Craig W.
(xnomanx) - F - M
Re: Why is there so much doubt about surface water contamination?? on 11/03/2013 17:05:35 MST Print View

No peer reviewed journal papers, just my own humble experience of not treating about 75% of the water I drink in the Sierra. But this is water typically above treeline, away from trail and pack animals, and off the beaten path of most people. If I can see the source, I typically drink without treating.

Ian B.
(IDBLOOM) - MLife

Locale: PNW
Re: Re: All of the above. on 11/03/2013 17:21:53 MST Print View

"Let''s take it as fact that Giardia can pass through the nose to infect.
Why????
Frankly, I think it is a rather silly idea. It has no realistic mechanism."

As a primary source? No probably not. As a potential source? Doubtful but sure. If for some reason you stick your contaminated finger three knuckles deep into your nostril to self administer the vulcan brain massage, then do the good ol' "snnnooorrrt..... haaaaaaaaaaaawk..... (gulp)", then the now giardia contaminated booger would be routed to the stomach in lieu of the lungs.

Author's note: After a quick test, I'm only capable of going one knuckle deep for vulcan brain massage purposes but from what I've seen sitting at a red light, many of my fellow citizens are capable of digging much further.

Ian B.
(IDBLOOM) - MLife

Locale: PNW
Re: Re: Re: All of the above. on 11/03/2013 17:26:35 MST Print View

Have we learned anything here other than that following good field hygiene practices and treating/filtering water are generally recommended to prevent beaver fever?

It'd be nice to hear Colin Crusor's (pretty sure I just screwed up his last name) opinion on the matter has he seems to be the resident expert. I'll try to find some of the other threads that he's commented in but if memory serves, giardia is capable of changing its antigens which affects the human bodies ability to develop a resistance to it.

Ian B.
(IDBLOOM) - MLife

Locale: PNW
Re: Re: Re: Re: All of the above. on 11/03/2013 17:34:54 MST Print View

Yep.... screwed Colin Krusor's name up. Some of his previous comments:

"Giardia have a trick called "antigen shifting". Giardia has a repertoire of more than 200 "variant surface proteins" and individual Giardia cells are constantly changing the ones that are on their surface at any given time so your immune system will never be able to recognize them as something it has seen before. There is a Giardia vaccine in development that uses whole inactivated Giardia cells that have been genetically manipulated so all of their protein wardrobe is on the surface at once. This is not likely to confer perfect immunity but it will get one's immune system better acquainted with more of Giardia's disguises, so it is more likely to recognize new Giardia cells as pathogens."

and http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=78686&skip_to_post=671000#671000

" have no desire to be alarmist, but I think it is important to note that Crypto and Giardia are the best known eukaryotic parasites in surface waters but not the only ones.

I study the protozoan parasite Toxoplasma. Toxoplasma oocysts cannot be killed by any chemicals that are safe to drink. After 24 hours in 6% bleach (twice the strength of the stuff in the bottle at a drug store) they are 100% viable and readily cause fatal infections in mice. In my lab, we store viable Toxo oocysts in sulfuric acid. Many human infections have been reported from ingestion of water contaminated with this parasite. In 1995, about 400 people in Victoria, BC became infected from municipal tap water (which was chlorinated). Subsequent research found that the source was toxoplasma-infected mountain lions living in the areas around the municipal reservoir. The parasites were being transported in the watershed. In some areas in California, the proportion of the mountain lion and bobcat population that has the infection approaches 80%. In humans, toxoplasmosis (like cryptosporidiosis) is typically a long-term subclinical infection following an initial bout of GI symptoms. However, it has also been implicated as a risk factor for schizophrenia and cognitive changes, and it is a serious risk to a fetus if a woman becomes infected while she is pregnant.

Cysts of eukaryotic parasites (worms and protozoans) are probably in all backcountry surface waters (excluding direct snowmelt) because they are shed in huge numbers by many wildlife species and (in contrast to bacteria and viruses) they accumulate because they are extremely tough and remain viable for months or years in water and soil. Polyparasitism (concurrent infection with multiple parasites) is certainly the norm in people in many developing countries now, and it was probably the norm among people in the US until about a century ago. On the American frontier, everyone probably had parasites, and people who continue to drink untreated water when backpacking probably have them as well.

In remote alpine areas with fast-moving streams (at the top of the watershed), the risk from pathogenic bacteria or viruses is minimal, so a large pore filter (like the Frontier Pro) is enough by itself, in my opinion. In areas lower down on a watershed, but still remote, a small pore filter (<0.3 microns) is probably adequate by itself (removes worm eggs, protozoa, and most bacteria). In lowland or coastal areas, or areas regularly used by other hikers or domestic animals, it seems to me that there are only three good options: boiling, steripen treatment, or a combination of filter+chemicals. In these higher-risk places, filters alone are risky because they don't remove viruses or small bacteria (ie, Lepto, Brachyspira, etc.), and chemical treatment alone is risky because it won't inactivate some protozoa.

I use a Sawyer Squeeze or a Sawyer gravity filter and carry Aquamira tabs. I can use the Sawyer alone in remote alpine places (and I have the Aquamira tabs in case the Sawyer freezes), and in lowland places I use both (and wait 30 minutes)."

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Re: All of the above. on 11/03/2013 17:41:57 MST Print View

"> Let''s take it as fact that Giardia can pass through the nose to infect.
Why????
Frankly, I think it is a rather silly idea. It has no realistic mechanism."

Well, not really. It actually does have a mechanism, Roger. Your nose and the rest of your mucus membranes are connected directly to your stomach and help reduce the effect of the acids, enzymes used in digestion. Most of the secretions end up in the stomach...hence your mechanism. You ingest mucus from your mouth and nose as a way to recycle salts, proteins, etc, and this is a normal part of breathing. One purpose is to protect the fragile lungs by directing contaminants to the more rugged digestive system, and, out of the body.

Buck Nelson
(Colter) - MLife

Locale: Alaska
THE skeptical giardia paper on 11/03/2013 19:20:53 MST Print View

Jennifer said: does anyone have any good scientific, peer-reviewed data that says drinking untreated surface water in the wild is NOT a risk for giardia?

I know of only one peer-reviewed paper saying there is little evidence people are contracting giardia from backcountry water. Giardiasis as a threat to backpackers in the United States: a survey of state health departments It is an extremely misleading and poorly designed paper. The CDC has specifically refuted Welch's conclusions. Welch is the source of most of the skeptical "science."

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: All of the above. on 11/03/2013 21:09:37 MST Print View

Hi James

> Your nose and the rest of your mucus membranes are connected directly to your stomach
Yes, but at a molecular transport level. I seriously doubt the transport mechanism is able to cart 10 micron cysts along all the way to the stomach!

> You ingest mucus from your mouth and nose
OK, that is possibly viable. But to say it is the top route for infection, greater than contaminated hands and water? Ummm...

I say again: show me the published research to support this claim. I am always open to convincing proof.

Cheers