Interesting Article on the Effectiveness of Hiker Water Treatment

[imscotty]

Saw this on the PCT-l list.

http://distancehiking.com/tools/watertreatment/

Myself, I plan ahead, choose my water sources carefully, and never filter or treat. I carry a few water treatment tablets in case I ever am forced to drink skanky water. So far, I have never needed them in the East.

[LoneStranger]

That is some pretty quacky data science in that article. If you want to filter/treat or not is your business, but I hate to see people do such ugly things with data and then pretend it means anything.

With the number of hikers on the AT going up every year and especially because more and more people are bringing pets along for company I think making sure your water is safe is going to become increasingly important. If you are visiting real back country the risks are going to be lower, but on a footpath super highway like the AT you aren't exactly in the back country. A family member suffered horribly with giardia for a long time before his doctor was able to get it under control and that is not a fate I wish to tempt.

[DLP]

I think that a lot of the problems blamed on water are really people not washing hands often or well enough. My sister in law has remarked that I wash my hands like I'm prepping to do surgery. :)

I also think that I drank enough lake and pond water when I was a kid... I might be immune. But I generally treat water.

Icky water on JMT might be due to horses. Or something dead in the water.

[Traveler]

I have to agree with Lone, most people typically are not able to say how they got an intestinal bug. How does one differential cramps and diarrhea from a water source versus food, versus a virus? Most people will blame food when its more likely a norovirus or contamination issue. You can contract a norovirus by shaking hands, fist bumps, picking up and moving gear, food prep, or any one of a dozen other sources. This includes places around water sources people communally use, rocks and trees for balance, etc. In fact there was just a Norovirus warning on WB recently. I don't find the data in that article sufficient to make any decisions on treating or not to treat water.

The medical paper referenced in the article was for a relatively small area of the Sierras where specific lakes and streams were tested for pathological bacterias. 22 out of 55 sources had pathogens like coliform, which is at the 40% level. Given animals carry and create these pathogens and parasites, treating water is simply a way of mitigating risk in that 40% of water sources.

Treat or don't treat water, its an individual choice. That article shouldn't be considered part of the scientific body of evidence to base the decision on though.

[Colter]

Taken at face value the survey says about 9% of people reported waterborne illness but that water treatment does no good, in fact it makes you more likely to get a waterborne illness.

Something doesn't make sense, and I think it's because it's all based on the guesses of laymen about how they got sick.

[squeezebox]

Untreated/unfiltered water is not worth the risk. The survey you pointed to is very iffy. Now which scientific journal did it come out of? Oh it didn't. Bottom line is people DO get sick from unfiltered water. I'll bet the unfiltered folks won't be honest about how they get sick. I don't understand what you think you get out of non filtering/treating?? Please explain.
oh yea!! use toilet paper and wash your hands.

[rickb]

If you want to see a REALLY unscientific poll, here is one I posted on Whiteblaze years ago:

http://www.whiteblaze.net/forum/showthread.php/10785-Poll-on-FIltering-and-Illness

What strikes me as mildly interesting is the fact that of the 20 Whiteblaze members who responded they never (or vary rarely) treated thier water, only two said they got sick.

That's 10 percent -- about the same as what we are reading now. :eek:

Obviously a very small sample, but still. Of the 55 Whiteblaze members who did treat thier water 6 percent said they got sick. Better, but not all that different from this larger poll we are reading now.

[Lone Wolf]

Untreated/unfiltered water is not worth the risk. I'll bet the unfiltered folks won't be honest about how they get sick. I don't understand what you think you get out of non filtering/treating??

i bet you're wrong. i've never gotten sick from not filtering/treating. what do i get out of it? clear, cool pure mountain water

[Traveler]

If you want to see a REALLY unscientific poll, here is one I posted on Whiteblaze years ago:

http://www.whiteblaze.net/forum/showthread.php/10785-Poll-on-FIltering-and-Illness

What strikes me as mildly interesting is the fact that of the 20 Whiteblaze members who responded they never (or vary rarely) treated thier water, only two said they got sick.

That's 10 percent -- about the same as what we are reading now. :eek:

Obviously a very small sample, but still. Of the 55 Whiteblaze members who did treat thier water 6 percent said they got sick. Better, but not all that different from this larger poll we are reading now.

The overarching problem remains, anecdotes are not data. Polls on this kind of thing provide an idea of how common intestinal illness experiences can be, assigning how they relate to treating water is subjective speculation. That said, these polls do tend to make one a bit more aware of washing hands and keeping food away from contaminated surfaces, implements, and people.

[rocketsocks]

Not all maladies present as tummy troubles, some viruses and bacterium can lay dormant for years causing all kinds of ailments, ie heart, lungs, brain, and the source or pathology is never known. How do I know this then? I don't, only what I've read. I'll treat and drink my water 15 min. later than those who don't treat...no biggie.

[rickb]

Coulter makes a strong case for filters/treatment.

[Walkintom]

If you want to see a REALLY unscientific poll, here is one I posted on Whiteblaze years ago:

http://www.whiteblaze.net/forum/showthread.php/10785-Poll-on-FIltering-and-Illness

What strikes me as mildly interesting is the fact that of the 20 Whiteblaze members who responded they never (or vary rarely) treated thier water, only two said they got sick.

That's 10 percent -- about the same as what we are reading now. :eek:

Obviously a very small sample, but still. Of the 55 Whiteblaze members who did treat thier water 6 percent said they got sick. Better, but not all that different from this larger poll we are reading now.

The problem is - can you trust self reporting when the ego is involved?

How many people admit when they lose money in the stock market? How many tell others about their venereal disease? How many own up to the unattractive sexual partner, etc?

[PilotB]

Why risk a hike ending illness? $40 to drink filtered water.

http://www.rei.com/product/858764/sawyer-squeeze-water-filter-32-fl-oz


If you cannot afford that, you cant afford thru.

[imscotty]

Untreated/unfiltered water is not worth the risk. The survey you pointed to is very iffy. Now which scientific journal did it come out of? Oh it didn't. Bottom line is people DO get sick from unfiltered water. I'll bet the unfiltered folks won't be honest about how they get sick. I don't understand what you think you get out of non filtering/treating?? Please explain.
oh yea!! use toilet paper and wash your hands.

Hello Squeezbox,
I think the point of the article is that no one really knows how they got sick. Many hikers blame the water source, when in fact it could be that privy, that shelter register, that shared gorp, or that handshake that made them sick.

Although not a scientific study with controls, 879 hikers is still a pretty large sampling. Honestly, just assuming not filtering their water is what makes hikers sick is not very scientific either.

I think the really telling thing was that regardless of filtration method used, or even when no filtration method was used, hikers got sick at virtually the same rate. Even if you think that their water was the source of the sickness, why would you continue to use methods that just do not seem to work?

[Colter]

Medical risks of wilderness hiking (http://www.ncbi.nlm.nih.gov/pubmed/12681456)

PURPOSE:
We sought to determine the extent to which injuries and illnesses limit long-distance or endurance outdoor recreational activities.

METHODS:
In a prospective surveillance study, 334 persons who hiked the Appalachian Trail for at least 7 days (mean [+/- SD] length of hike, 140 +/- 60 days) in 1997 were interviewed. At the end of their hike, subjects completed a questionnaire on injuries, illnesses, water purification methods, and hygiene practices.

RESULTS:
Of the 280 backpackers who responded (a combined 38,940 days of wilderness exposure), 69% (n = 192) achieved their goal. The most important reasons for ending a hike prematurely were injury, time limitation, and psychosocial reasons. The most common medical complaints were feet blisters (64%; n = 180), diarrhea (56%, n = 156), skin irritation (51%, n = 143), and acute joint pain (36%, n = 102). The incidence of vector-borne disease was 4% (n = 11); physician-diagnosed Lyme disease was the most common, and 24% of hikers (n = 68) reported tick bites. The risk of diarrhea was greater among those who frequently drank untreated water from streams or ponds (odds ratio [OR] = 7.7; 95% confidence interval [CI]: 2.7 to 23; P <0.0001), whereas practicing "good hygiene" (defined as routine cleaning of cooking utensils and cleaning hands after bowel movements) was associated with a decreased risk (OR = 0.46; 95% CI: 0.22 to 0.97; P =0.04).

CONCLUSION: Diarrhea is the most common illness limiting long-distance hikers. Hikers should purify water routinely, avoiding using untreated surface water. The risk of gastrointestinal illness can also be reduced by maintaining personal hygiene practices and cleaning cookware.

[LoneStranger]

Hello Squeezbox,
I think the point of the article is that no one really knows how they got sick. Many hikers blame the water source, when in fact it could be that privy, that shelter register, that shared gorp, or that handshake that made them sick.

Although not a scientific study with controls, 879 hikers is still a pretty large sampling. Honestly, just assuming not filtering their water is what makes hikers sick is not very scientific either.

I think the really telling thing was that regardless of filtration method used, or even when no filtration method was used, hikers got sick at virtually the same rate. Even if you think that their water was the source of the sickness, why would you continue to use methods that just do not seem to work?

Self reporting is the issue here and it invalidates the data no matter how large the sample. Those who do not filter will not report getting sick from not filtering because it doesn't fit with their preconceived notion that they are smarter than giardia or other waterborne contaminants. Those who filter because they believe water can be contaminated are much more likely to report that bad water made them sick even if the water had nothing to do with it because of their preconceived notion that the water is out to kill them.

I always filter even in the deep back country, but you do what makes you happy. Having seen dead animals rotting in "pristine" water sources and noting that all those folks bringing their pets out on trail never seem to have a bag to carry their dog's waste I'm going to err on the side of caution.

[Traveler]

I think the point of the article is that no one really knows how they got sick. Many hikers blame the water source, when in fact it could be that privy, that shelter register, that shared gorp, or that handshake that made them sick.

I think the really telling thing was that regardless of filtration method used, or even when no filtration method was used, hikers got sick at virtually the same rate. Even if you think that their water was the source of the sickness, why would you continue to use methods that just do not seem to work?

The point overall is well taken and enlightening, most short term duration intestinal bugs are more likely from people contact directly, or from secondary surfaces/implements, not from water sources necessarily.

Conversely, contaminated water illnesses tend to be fairly serious, of longer duration and acute symptom development, and require medical attention, as opposed to the more common 24-36 hour diarrhea from noroviruses. Some examples;

E-coli infections from water will typically include a very high fever, bloody diarrhea, and last for about a week. Following that kidney (including renal failure) and blood problems like anemia can occur about two weeks after the onset of diarrhea.

Cryptosporidiosis (Crypto). The symptoms can appear 2 - 10 days after ingestion and be debilitating, including headache, watery diarrhea, cramping, nausea/vomiting, and low fever. An MD is needed to determine this parasite is present. There is no medical treatment has been found that is routinely effective, essentially if you get this, you have to live through it. Dehydration becomes the looming issue with the loss of fluids from the body and most activity will stop until the symptoms go away when the parasite finally does.

Giardiasis, infection. starting from 5 to 25 days after ingestion also has to be diagnosed via a lab test and has similar symptoms to the above. Fortunately there are some medical treatments that are used to eradicate the parasite. Dehydration is severe and likely to stop any activity until the symptoms end.

These things reside in the environment and are the top three reasons I will filter water. Nanoviruses are far less of a medical threat than these are. The risk of contracting any of these at any given untreated water source is low, the odds increase as the number of untreated water sources increase however. Mitigating the threat of these life endangering ailments (and other water borne pathogens) is what I am interested in by using a very simple process of filtering or treatment.

For me, the time it takes for this prevention is worth it, given the consequences of failure. I have buddies who do not feel they either can or will contract any of these things because they haven't yet and continue to drink untreated water. Its a personal decision.

This is an excellent topic, thanks for rolling this out, imscotty!

[kf1wv]

2-3 oz. inline or squeeze filter. No worries.

[imscotty]

Medical risks of wilderness hiking (http://www.ncbi.nlm.nih.gov/pubmed/12681456)

PURPOSE:
We sought to determine the extent to which injuries and illnesses limit long-distance or endurance outdoor recreational activities.
.

Thank you for the link Colter, here is another study...

http://www.ncbi.nlm.nih.gov/pubmed/14769284

These studies seem to indicate a decrease risk of diarrhea among hikers who treat their water. It would be great to see a study that broke out the different filtration methods and products. The studies also seem to indicate that 'good hygiene' (hand washing, etc) was the most important factor in maintaining health on the trail. I still suspect that most hikers are getting sick from the shelters, the privies and from other hikers.

[imscotty]

Self reporting is the issue here and it invalidates the data no matter how large the sample. T.

That would seem to be the issue even with the two peer reviewed studies cited above.

[Pedaling Fool]

That's the problem with most studies in the area of human health – they rely too much on self reporting.
It's why I don't really pay much attention to this area of science and just use basic common sense.

Much of what we know is from a lack of ethics, but not enough done. Think of what we could learn if we used prisoners as guinea pigs.



http://www.livescience.com/13002-7-absolutely-evil-medical-experiments-tuskegee-syphilis.html

[rickb]

Thank you for the link Colter, here is another study...

http://www.ncbi.nlm.nih.gov/pubmed/14769284

These studies seem to indicate a decrease risk of diarrhea among hikers who treat their water. It would be great to see a study that broke out the different filtration methods and products. The studies also seem to indicate that 'good hygiene' (hand washing, etc) was the most important factor in maintaining health on the trail. I still suspect that most hikers are getting sick from the shelters, the privies and from other hikers.


Look closer.

Right off the bat they state that out of 280 hikers only 56% total got Diarrhea.

If you were in a group of 12 hanging around the outhouse who were in that unfortunate 56%, 5 would have filtered thier water and 7 would have not.

But a whole lot of your friends would have been doing just fine whether they filtered or not. That number matters.

But what if you just want to improve your odds-- even a little? This study proves filtering helps some, right?

Well, it should be considered but "prove" might not be the best word.

If you are in the group with the Diarrhea who didn't filter, you would need to ask yourself if you and your fellow unfiltering risk takers share any other characteristics with each other to a bit greater degree than those poor souls who filtered and got sick anyway. That could explain the small delta between the 7 of you and the 5 of them.

But in the end, who knows. Sucks for everyone who was not among those in tht study that did not get afflicted. Again, that number matters.

Edit-- On thing confused me looking at the abstract. They stated that 56% of the 280 hikers got diarreaha, but also stated N = 56 suggesting a much lowere percentage. Hard to really get into that without seeing the actual raw data.

[perdidochas]

i bet you're wrong. i've never gotten sick from not filtering/treating. what do i get out of it? clear, cool pure mountain water

Filtering, you still get clear, cool pure mountain water.

[perdidochas]

Self reporting is the issue here and it invalidates the data no matter how large the sample. Those who do not filter will not report getting sick from not filtering because it doesn't fit with their preconceived notion that they are smarter than giardia or other waterborne contaminants. Those who filter because they believe water can be contaminated are much more likely to report that bad water made them sick even if the water had nothing to do with it because of their preconceived notion that the water is out to kill them.

I always filter even in the deep back country, but you do what makes you happy. Having seen dead animals rotting in "pristine" water sources and noting that all those folks bringing their pets out on trail never seem to have a bag to carry their dog's waste I'm going to err on the side of caution.

I agree. The dead animals rotting in otherwise pristine water is the reason I filter. Saw a dead armadillo corpse in a small creek on my last weekend trip.

[kayak karl]

I'll bet the unfiltered folks won't be honest about how they get sick. it's the people that filter their water that lie they STILL got sick from the water. heaven forbid it was their poor hygiene practices. :)

[imscotty]

Well, it should be considered but "prove" might not be the best word.

If you are in the group with the Diarrhea who didn't filter, you would need to ask yourself if you and your fellow unfiltering risk takers share any other characteristics with each other to a bit greater degree than those poor souls who filtered and got sick anyway. That could explain the small delta between the 7 of you and the 5 of them.

.

I thought the same thing RickB. Correlation does not imply causation. Perhaps people who do not filter are also taking risks with their hygiene. I would rather not think about what that may say about me :)

[rickb]

I thought the same thing RickB. Correlation does not imply causation. Perhaps people who do not filter are also taking risks with their hygiene. I would rather not think about what that may say about me :)

Wives could have something to do with it.

I have it on good authority that some of those who require all water be filtered, also repealed the 5 second rule on dropped food. On balance, probably some wisdom there.

In the interest of full disclosure, I filter most of the time these days. No choice and no debate in my real world.

[Traveler]

Wives could have something to do with it.

I have it on good authority that some of those who require all water be filtered, also repealed the 5 second rule on dropped food. On balance, probably some wisdom there.

In the interest of full disclosure, I filter most of the time these days. No choice and no debate in my real world.

"Happy wife, happy life" tends to ring true, its the wise who follow that path.

[Colter]

Self reporting is the issue here and it invalidates the data no matter how large the sample. Those who do not filter will not report getting sick from not filtering because it doesn't fit with their preconceived notion that they are smarter than giardia or other waterborne contaminants. Those who filter because they believe water can be contaminated are much more likely to report that bad water made them sick even if the water had nothing to do with it because of their preconceived notion that the water is out to kill them...


What LoneStranger said.

[Kevin108]

Taken at face value the survey says about 9% of people reported waterborne illness but that water treatment does no good, in fact it makes you more likely to get a waterborne illness.

Definitely doesn't add up. Reminds me of a similarly confusing study I saw a few years ago about the stopping power of different handgun rounds. The curve it showed indicated somewhere between 9mm and .380, getting shot could be good for you.

Mom taught me early on not to believe everything I read.


Sent from my iPhone using Tapatalk

[podin04]

There's been lots of good discussion here that I have enjoyed reading. Wanted to make a few comments myself.

1) There been a lot of commentary on this and other sites about how the survey relied on self-reporting and this somehow "invalidates the data" or otherwise renders the investigation worthless. It's true that having hikers report whether or not they got sick from water is really asking about their perception of whether it was water that made them sick. We'll never know for sure whether it was actually something from the water or something else that made a sick hiker sick. But this doesn't invalidate or render the information useless. There is always information to be gained, even if we're not taking blood samples in a perfectly designed randomized controlled double blind study that's published in Lancet. We just need to make sure we are drawing appropriate conclusions. There's the perception that if a study isn't tightly controlled or lacks a control then there's nothing to be gotten from it. I disagree.

2) One of the commenters cited a study by Boulware, et. al. (http://www.ncbi.nlm.nih.gov/pubmed/12681456), in defense of always treating water. This study was, in fact, a survey of 280 AT hikers. The researchers intercepted the hikers on the AT between NC and NH, got their addresses, and mailed them a 4-page survey, very similar to how my survey (http://distancehiking.com/tools/watertreatment/) was conducted.

I want to go over a few other points from this study that aren't apparent just from reading the abstract. One of the outcomes looked at by the researchers was the incidence of diarrhea, measured as number of instances per month:

-While it's true that hikers who drank untreated water from streams and ponds more then several times per week were more likely to have diarrhea, there was no relation between diarrhea and those who drank untreated spring water.

-The difference in diarrhea incidence between those who regularly treated and those who didn't was 1.1 days per month. The water filterers experienced diarrhea 0.5 days per month and the hikers who drank untreated water from streams and ponds had an incidence of 1.6 days per month. Based on my own long distance hiking experience, 0.5 or 1.6 days of diarrhea per month; that ain't bad either way. And for the record I always treat my water (surprised?) So while the odds ratios may point to a significant lowering of risk with treating water, the actual "clinical significance" i.e., the meaningfulness of the numbers on a real-world scale, seems small.

-45% of hikers who treated water got diarrhea anyway.

-The researchers spent quite a lot of time discussing the importance of hand hygiene. Here's a quote from the RESULTS section. "Of the 14 behaviors examined, three correlated with a reduced risk of diarrhea when performed routinely: consumption of vitamins, cooking utensils with soap and water, and washing hands after urination. These associations were independent of water disinfection behaviors or hiking duration."


So regardless of whether a study subject treated his or her water, vitamin consumption, cleaning with soap and warm water, and washing hands all reduced the risk of diarrhea.

The Boulware study does not establish causation for water treatment or anything else. It simply describes associations and relationships. Their conclusion that "hikers should purify their water routinely" was overreaching for a survey-based study that simply describes associations and dos not establish causation.

3) Lastly, go back and read my article again. The conclusion I drew from the data was not that we should all stop treating water. My survey data looked at trends and perceptions, but didn't establish causation for this question. The article's conclusion was that we should be discussing hand hygiene just as much, if not more, than water quality/purification when talking about how to prevent hikers from getting sick in the backcountry. It's a conclusion supported by the Boulware study data as well. It was a conclusion meant to stimulate discussion, which it did :-) I think my mistake was in using the catchy title "Is water treatment necessary?" which may have put some instantly on the defensive.

Thanks everyone for the good discussion. I'll be posting more analysis from the survey later this week on distancehiking.com (http://distancehiking.com)

Dan

[Colter]

While it might be true that the data in your study isn't invalidated, bias invalidates the apparent conclusion. Boulware doesn't rely on people determining the source of their sickness. That's a night and day difference.

In the Boulware study you downplay non-treaters being sick one more day per month. Most people would say being sick five or six more days on a thru-hike is a pretty big deal. Especially if it's giardia.

[rickb]

-The researchers spent quite a lot of time discussing the importance of hand hygiene. Here's a quote from the RESULTS section. "Of the 14 behaviors examined, three correlated with a reduced risk of diarrhea when performed routinely: consumption of vitamins, cooking utensils with soap and water, and washing hands after urination. These associations were independent of water disinfection behaviors or hiking duration

Too bad the full studies are not available on line.

I have a bunch of questions, but one that comes immediately to mind is if any urine that may get on my hands after peeing in the woods is a vector for diarrhea and disease.

Seems like they conclude it is, but I always though if you took the "ick" factor out of not washing your hands after peeing, there wasn't any significant health risk to yourself for not doing so.

I do think washing hands is important, but just not making the same connections as suggested in the study -- happy to pe corrected on that point, however.

[Gray Bear]

A lot of good data being dissected in this thread. One aspect I see missing is the effect that lack of rest has on our body's ability to defend itself. Day after day of physically demanding activity compounded by lack of good rest at time has to be a factor. Along with a typically poor high sugar diet certainly has to have an effect on the immune system.

Myself I'm an occasional filter user but I'm typically not on a super highway either. If I were traveling in the bubble I would most likely filter much more but sanitation would be far more of a concern than the water.

[Another Kevin]

Seems like they conclude it is, but I always though if you took the "ick" factor out of not washing your hands after peeing, there wasn't any significant health risk to yourself for not doing so.

I do think washing hands is important, but just not making the same connections as suggested in the study -- happy to pe corrected on that point, however.

I wondered about that myself.

The various studies seem to show that objects touched by unwashed hands - shelter registers and whatnot - are significant vectors.

I bet your trousers pick up a lot of nasties. And they don't seem to get laundered as regularly on the trail as they do in town. And you're handling them every time you pee.

Either that, or else regular handwashing is a marker for concern about sanitation in general, or else that washing your hands after you pee cleans up nasties that you picked up from other places than your you-know-what.

Generally speaking, you won't get sick from your own bugs - they're already in you.

[Sarcasm the elf]

30504
Just sayin...

[Colter]

We are mixing two Boulware studies to some degree, but I don't think it matters too much. To quote from Influence of Hygiene on Gastrointestinal Illness among Wilderness Backpackers (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.researchgate.net%2Fprofile%2F David_Boulware%2Fpublication%2F8881293_Influence_o f_hygiene_on_gastrointestinal_illness_among_wilder ness_backpackers%2Flinks%2F542edc8e0cf29bbc1270569 a.pdf&ei=in0mVcGiO4ncsAWnpYDQCA&usg=AFQjCNHM171Ei8IG2G6ZFQ7jAzZr0gt85w&sig2=JXvJ7mTDYBpJ0hv2sJnQkg&bvm=bv.90237346,d.b2w) (You should be able to read the whole paper at that link.)

Some of the behaviors, such as handwashing after urination, may serve more as markers for meticulous hygienic practices overall. The accrued benefit comes probably not from washing sterile urine off one’s hands, but through regular handwashing 3–4 times daily.

Water treatment vs. hygiene is a false choice. Both will significantly improve your odds of staying healthy. There is plenty of data to support that view.

[teefal]

\
Just sayin...

78 virgin mothers in NC. I had no idea this was so common. Aliens?

[perdidochas]

That is some pretty quacky data science in that article. If you want to filter/treat or not is your business, but I hate to see people do such ugly things with data and then pretend it means anything.

With the number of hikers on the AT going up every year and especially because more and more people are bringing pets along for company I think making sure your water is safe is going to become increasingly important. If you are visiting real back country the risks are going to be lower, but on a footpath super highway like the AT you aren't exactly in the back country. A family member suffered horribly with giardia for a long time before his doctor was able to get it under control and that is not a fate I wish to tempt.


The extra few ounces of my water filter is well worth the freedom from giardia.

On my last backpacking trip in the Sipsey wilderness, we saw a dead armadillo in one water source, and dog feces on the trail. I'm not going to risk drinking either of those if I can use my sawyer gravity filter instead.

[Redrowen]

Getting a case of the squirts out in the bush is always fun and builds character. :) I’m a firm believer in proper risk management with every endeavor I partake and always treat my water when resources permit. IMO Poor personal hygiene is the main cause of getting the squirts while out on the trail. I think too many people mistakenly rely on what I call hiker’s snake oil (hand sanitizers) for proper hygiene.

[imscotty]

@RickB
[Quote: 'I have a bunch of questions, but one that comes immediately to mind is if any urine that may get on my hands after peeing in the woods is a vector for diarrhea and disease.'}

I have always been taught that urine is a pretty sterile waste product. I can tell you that on my Grand Canyon/Colorado River rafting trip standard practice is to pack all 'solid' wastes out, and to just pour all 'liquid waste' (urine) into the river. The same river that was the source for our cooking and cleaning water.

@Kevin
[Quote: 'I bet your trousers pick up a lot of nasties. And they don't seem to get laundered as regularly on the trail as they do in town. And you're handling them every time you pee.']

Kevin, the thing that always gives me the skivvies is my shoe laces. The areas around shelters can be filled with disgusting land mines that we drag our laces through. If I go to retie my shoes, those hands are not going near my mouth until I have a chance to wash up again. Taking a leak, honestly, I'm not worried about that very much. I know where that has been, and it is clean :)

[Colter]

...The conclusion I drew from the data was not that we should all stop treating water. My survey data looked at trends and perceptions, but didn't establish causation for this question...

Yet there's a clear connotation that treating water is a waste of time. Here's what you said on Facebook: ...the same proportion of people who treat and don't treat get sick. So practice good hand hygiene above all else. Seems like you think it did establish causation.

Did your survey even ask any questions about hygiene?

[rickb]

Since I am forced to filter water for reasons explained earlier, my concern was not whether filtering was a waste of time, but rather if my Sawyer Mini was putting me at additional risk.

As one who now hikes only a fraction of the miles walked by those taking place in these studies, my risk to begin with (or prior probability for those with a Bayesian bent) of getting sick is relatively low.

The idea that I am now required by the wife to concentrate Giardia cysts in a little plastic tube -- a leaky one at that -- sort of disturbed me. Without any scientific understanding of these things I figured I could fend off a few solitary cysts, but that a Horde of them all together could overwhelm us both if they got loose.

Sort of like with zombies on the Walking Dead.

From what I am reading here, I see those concerns we probably misplaced-- even if my filter leaks bit -- because they all do.

I am going to have nightmares about shoelaces now, though.

[imscotty]

Since I am forced to filter water for reasons explained earlier, my concern was not whether filtering was a waste of time, but rather if my Sawyer Mini was putting me at additional risk..

I have had the same thoughts RickB. I am sure the manufactures have studies demonstrating the effectiveness of their products in the lab, but who knows what can happen in the field. It would be interesting to see which devices truly remain effective (and sterile) after a few weeks on the trail.

[Another Kevin]

I have had the same thoughts RickB. I am sure the manufactures have studies demonstrating the effectiveness of their products in the lab, but who knows what can happen in the field. It would be interesting to see which devices truly remain effective (and sterile) after a few weeks on the trail.

One thing that I suspect might help. I try to flush the filter every so often with water that's got a double dose of Aqua Mira. (I then dilute the remaining water with filtered water before drinking it, so I'm not getting the double dose of ClO2). I suspect that having the ClO2 in contact with whatever is on the inlet side of the filter will help control whatever nasties are growing there.

When I used a MSR pump filter, I would boil the element, and bleach everything else, before putting it away after a weekend trip. I don't think a Sawyer is boilable, more's the pity.

[Fredt4]

A couple of factors that probably impact the results are age & experience. Older hikers may have more experience and may be more selective about their water source. In addition they may have more immunities to any given contamination, sort of like "Been there, done that". I hiked the AT in 2011 with no filter and caught no illnesses. I was selective about my water and occasionally boiled the water. I know that gardia is a greater threat to younger children than older adults. My experience is that younger persons are more communal in their behavior, therefore have greater opportunities to get and spread illnesses. In addition babies and everything about babies is just nasty. Older adults probably have fewer contact with babies (at home before they get on the trail), and anyone touching babies or touching anyone (or anything) touched by a baby is more likely to bring the illnesses with them to the trail. I read an article by a researcher many years ago about how common colds are spread and methods of prevention. He noted at the end of the article that given he had a baby and other small children in his household that it was pointless for him to try to avoid getting the various variations of colds as it was impossible due to the children's behavior, basically they touch everything and there's no avoiding it.


Therefore it's reasonable to ask if the filters are merely delaying the various illnesses or preventing the spread of the illnesses. If I get one variation of gardia today, I'll probably have a minor or no reaction (perhaps unnoticeable) to that variation if infected years later. Several years ago a swine flu that was spreading around Mexico was having a greater impact (deadly) on younger, healthier adults. Turns out that older people had been vaccinated against a previous variation the back in the '70, and the vaccination was providing protection against the new strain. Hence the new strain wasn't targeting younger healthier adults, it was targeting adults without previous exposure to similar strains.


Old Chinese proverb says, "One illness, short life. Long life, many illness."

[Colter]

...If I get one variation of gardia today, I'll probably have a minor or no reaction (perhaps unnoticeable) to that variation if infected years later...

Maybe. But a person may never build up resistance to all strains of giardia that infect humans. I had giardia at least twice decades ago. Many years later I got the sickest yet with giardia on the PCT.

[jeffmeh]

A couple of factors that probably impact the results are age & experience. Older hikers may have more experience and may be more selective about their water source. In addition they may have more immunities to any given contamination, sort of like "Been there, done that". I hiked the AT in 2011 with no filter and caught no illnesses. I was selective about my water and occasionally boiled the water. I know that gardia is a greater threat to younger children than older adults. My experience is that younger persons are more communal in their behavior, therefore have greater opportunities to get and spread illnesses. In addition babies and everything about babies is just nasty. Older adults probably have fewer contact with babies (at home before they get on the trail), and anyone touching babies or touching anyone (or anything) touched by a baby is more likely to bring the illnesses with them to the trail. I read an article by a researcher many years ago about how common colds are spread and methods of prevention. He noted at the end of the article that given he had a baby and other small children in his household that it was pointless for him to try to avoid getting the various variations of colds as it was impossible due to the children's behavior, basically they touch everything and there's no avoiding it.


Therefore it's reasonable to ask if the filters are merely delaying the various illnesses or preventing the spread of the illnesses. If I get one variation of gardia today, I'll probably have a minor or no reaction (perhaps unnoticeable) to that variation if infected years later. Several years ago a swine flu that was spreading around Mexico was having a greater impact (deadly) on younger, healthier adults. Turns out that older people had been vaccinated against a previous variation the back in the '70, and the vaccination was providing protection against the new strain. Hence the new strain wasn't targeting younger healthier adults, it was targeting adults without previous exposure to similar strains.


Old Chinese proverb says, "One illness, short life. Long life, many illness."

My personal experience suggests that it is not that the baby that communicates nasties, in a relatively clean home where the parents practice good hygiene. Rather, when the child first goes to day care or nursery school, the "fun" really starts. :)

[LoneStranger]

If I get one variation of gardia today, I'll probably have a minor or no reaction (perhaps unnoticeable) to that variation if infected years later.

Keep in mind this does not mean you won't be infected, only that you will be asymptomatic. You would still be capable of spreading the infection to others who may not have the same immunities. People and dogs are major vectors for giardia and I'd wager most of them are in this group who no longer feel sick so have no clue what they are leaving behind.

[Another Kevin]

My personal experience suggests that it is not that the baby that communicates nasties, in a relatively clean home where the parents practice good hygiene. Rather, when the child first goes to day care or nursery school, the "fun" really starts. :)

And the whole household enjoys much better health once the kids learn to wipe their own .... noses.

[Traveler]

Keep in mind this does not mean you won't be infected, only that you will be asymptomatic. You would still be capable of spreading the infection to others who may not have the same immunities. People and dogs are major vectors for giardia and I'd wager most of them are in this group who no longer feel sick so have no clue what they are leaving behind.

A good point, indeed. There is really no immunity from parasites, most people will exhibit symptoms, some people (around 15% of those infected) are asymptomatic and don't have any outward signs of the parasite but are still infected and will spread it for a long time. Though the chances are fairly low in exposure to this parasite in water you may find in the forests, Giardiasis at least can be treated, though it takes a while to be rid of all the symptoms.

There are far more serious parasites and bacteria that are more common to find in water that will ruin your day. Campylobacter, cryptosporidium, and E. Coli are far more common and do not have reliable medical treatments, a course of antibiotics may work with Campy, however there are a lot of "ifs" in that. With this nasty stuff most all that can be done is to keep people hydrated with IVs and. If you are not strong enough, has a compromised immune system, or have kidney illness, exposure can be lethal.

Some champion the risk of exposure is low. However, with any risk comes consequence of failure, in this instance the consequence of failure is significant if not extreme, which is why I filter water where ever I get it.

[Fredt4]

Maybe. But a person may never build up resistance to all strains of giardia that infect humans. I had giardia at least twice decades ago. Many years later I got the sickest yet with giardia on the PCT.

"The intestinal parasite Giardia lamblia changes outfits nearly as often as a fashion model on a Parisian runway. With more than 200 protein coats in its molecular wardrobe, this troublesome creature—the cause of innumerable cases of diarrheal infections each year—can change its appearance from one instant to the next, throwing the body’s immune cells off track."

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