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Worms in the Water: Are Chemical Treatments and UV Too Risky?
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Home › Forums › General Forums › Food, Hydration, and Nutrition › Worms in the Water: Are Chemical Treatments and UV Too Risky?
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Aug 29, 2011 at 12:26 pm #1278657
Why do many backpackers ignore the risk of worms or worm eggs in their water? Chemical treatments and UV light aren't effective against them. It appears that raccoon roundworm is very prevalent in raccoons, and one site even implies that the eggs are resistant to boiling water:
"To destroy the egg you must use boiling lye or propane torching."
http://www.mass.gov/dfwele/dfw/wildlife/diseases/raccoon_roundworm.htmHere's one of the possible effects:
http://www.cbsnews.com/video/watch/?id=6888137nI've drunk untreated water before, but I think I'm switching to drinking only filtered water.
Of course, it's really a question of how likely it is that the eggs are actually in the water. I might risk a long bout of diarrhea, but I'm not willing to put my brain or other essential organs at risk.
Aug 30, 2011 at 4:21 pm #1774476This is yet another reason for me to justify the weight of my filter. Bleh.
Aug 30, 2011 at 4:33 pm #1774486but at least out west for us we rarely treat even, let alone filter – probably 90% of the water we drink is coming off of alpine snow slopes fresh from melting within a few hours or else coming straight out of the ground from snow melt above and thus ground-filtered. we treat from lakes though. if/when we ever get sick sick from water, we'll probably change our behavior but years going and no problems so..
Aug 30, 2011 at 10:34 pm #1774577It's called baylisascariasis (caused by Baylisascaris procyonis, a raccoon roundworm). It's really, really horrible, but also really quite uncommon – per the CDC, there have been only 13 well-documented cases of pretty bad central nervous system involvement reported… It is usually contracted by children that are playing with or eating dirt contaminated with raccoon f*ces (containing the eggs) in raccoon-heavy areas (often their own back yards).
One for the "too much information" file, from your friendly medical microbiologist/pathologist backpacker…
Edit to add: Not sure how this guy got it, but it might be prudent to filter if gathering water from areas with big raccoon populations…
Aug 30, 2011 at 11:05 pm #1774583It's ignored due to the low risk of this occurring in general – there are many competing risks and there are many others that have a much higher probability. It's like worrying about being attacked by a shark while swimming but ignoring the fact your more likely to drown or being in a plane crash while ignoring the hazards associated with driving your vehicle everyday. Concerned about cancer even though at most age groups your much more likely to die from a cardiovascular event. Very dramatic terrifying events, but unlikely to actually occur relative to other much more common risks.
However, the risk is not constant -this may be an issue with significant raccoon populations and may warrant precautionary measures. If I'm in New Jersey hiking I'm being cautious of deer ticks due to them being a lyme disease vector and the risk is real there per the epidemiology studies. Here in WA though, lyme disease isn't an issue so why worry about it?
Where you hike are there significant populations of raccoons?
Aug 31, 2011 at 8:22 am #1774648In the adult, I'd bet inhalation would be more common. Raccoons tend to live in attics of older homes so being in the attic without a proper mask would be one way on contracting the bug.
Sep 1, 2011 at 10:08 am #1775055@Kristin: With it being so prevalent in raccoons, and the eggs being so hardy, I wonder if baylisascariasis isn't more common. Maybe it just rarely causes obvious problems? Maybe it commonly eats away at the part of the left parietal cerebral cortex which causes people to fail to realize they don't really need to carry a heavy pack? :)
@Ryan: I agree. There are raccoons in the areas I hike (Appalachians and foothills), although I wouldn't say there are significant numbers. I guess I just don't like the Russian roulette approach to water safety. The water is most likely clean, but there might be a raccoon latrine just upstream too.
@John: True, good point.
@Matt: Right, different situation in the high mountains… unless maybe mountain goats and marmots can be carriers of any dangerous worms?
@Laurie: My perspective exactly. The risk is enough to make me choose filtration over chemical or UV. I don't like adding chemicals to the water anyway, and I'm skeptical of relying on electronics with batteries. The admittedly small risk of baylisascariasis or even a less dangerous worm is enough to sway me toward filters over other methods. Btw, I just got a Sawyer Squeeze filter which is 4.5 oz (wet weight, including dirty bag). That's heavier than chemicals, but around the same as UV, and tastes better than chemicals.Sep 1, 2011 at 1:06 pm #1775108What size filter is needed for keeping eggs out?
If they are big like Cholera, then a couple of layers it tight woven cloth would be
a possible filter. Then the water could be otherwise treated.Sep 1, 2011 at 1:21 pm #1775111"Baylisascaris procyonis eggs are 80-85 µm by 65-70 µm in size"
http://www.dpd.cdc.gov/DPDx/html/ImageLibrary/A-F/Baylisascariasis/body_Baylisascariasis_il1.htm
It sounds like a material with a 40 µm pore size would be adequate, to be on the safe side. What type of material has a pore size <= 40 µm?
Sep 1, 2011 at 1:36 pm #1775119The Steripen prefilters are 40×40 µm, as one that comes to mind. Pretty coarse, actually.
Cheers,
Rick
Sep 1, 2011 at 1:40 pm #1775120"An old cotton sari, folded, creates a smaller effective mesh size (approximately 20-μm). This should be small enough to remove all zooplankton, most phytoplankton, and thus a large proportion of the cholera in the water (99%, according to laboratory studies). However, the nylon net with the larger mesh size was found to be "almost equally effective."[2]"
http://en.wikipedia.org/wiki/Cloth_filter
—
What is the pore size of a bandana?
about 100μm
"Do Bandanas Provide Protection?
Bandanas have been used by wildland firefighters for decades, however, they should not be considered a viable
choice for respiratory protection. Scanning electron microscope photographs of both new and used bandanas have
shown openings (pore sizes) within the fabric that exceed 100 μm in length and width, which allow particulate matter
to pass freely through the fabric (Reh and others 1994)."http://www.fs.fed.us/eng/pubs/pdf/hi_res/07511301hi.pdf
—
So it looks like a tight woven cloth would work, but it would need to be tighter than
a common bandana and it would need to be folded at least once.Sep 1, 2011 at 3:47 pm #1775162@Andy: Lower frequency of clinically apparent disease may be a dose-related effect. A number of the case reports I've read have involved children with developmental disorders or autism who eat a lot of the stuff… Do note that humans are not part of the normal life cycle of this worm, but are "incidental hosts" (which fits with a low prevalence). EDIT TO ADD: I like the idea that this explains why some people don't realize they don't have to carry a heavy pack. Unfortunately, that would mean that I was infected for many years and suddenly got better… :D
@John: The eggs are too large to be inhaled and cause infection through the pulmonary route. Andy beat me to it in posting the size of the eggs, but they're quite large…Sep 1, 2011 at 4:39 pm #1775177AnonymousInactive"An old cotton sari, folded, creates a smaller effective mesh size (approximately 20-μm). This should be small enough to remove all zooplankton, most phytoplankton, and thus a large proportion of the cholera in the water (99%, according to laboratory studies)."
I'm skeptical of this, given that the size of a cholera bacterium is 1-5 microns.
Sep 1, 2011 at 8:09 pm #1775241@Kristin: That makes sense I guess. The more worms there are, the more likely they'll burrow into something important. Ha ha! Good point about the heavy pack part! :D
Sep 2, 2011 at 6:49 am #1775326Tom, I too am skeptical. A micron is pretty darn tiny.
Sep 2, 2011 at 7:32 am #1775337In the last year or two there have been a lot of scary articles about this in the papers – but it is still pretty rare overall.
IMO you have more to fear with gardening bare handed in raccoon areas (where we live we have plenty of them loitering around due to a healthy population of feral cats). Anyhow….the whole point is that you can pick them up doing normal activities – but that I agree with other posters here: in the West up high you never see coons. Coons like the coast where the living is easy and the food is easy to get – for example you see them on the coastal strip as they looooovvvveeee shellfish. But outside of there and car campgrounds I have never seen one above 1K in elevation. Coons are opportunistic critters and like life to be easy. Alpine isn't easy. And more so coming from experience (I lived on an Island for 1 1/2 decades) they like to stay put once they find a gravy train – and live there, breed there and breed some more. In other words, right under your bedroom since you live right above a lovely cove of water.
Sep 2, 2011 at 7:52 am #1775338I hate it when I finally get comfortable with my water treatment and someone makes me question if I'm doing enough all over again. ;)
Sep 2, 2011 at 7:59 am #1775341Yup. You can get worms from going barefoot too.
There are raccoons around Lake Union in the center of Seattle. I live a few miles north and we have them all over, along with beaver, eagles, hawks, great blue herons, opossum and coyotes– and even an occasional black bear or cougar.
+1 on the raccoons on the coast. Bear cans are required on the Olympic Beaches. We haven't seen a bear in over 20 years, but the raccoons are numerous and the cans help there. The lil' monsters will come right up to your camp in broad daylight.
Sep 2, 2011 at 1:58 pm #1775485"I'm skeptical of this, given that the size of a cholera bacterium is 1-5 microns."
You filter out the host and the host's food, which are much larger. When you reduce the
total load (number of things being ingested) you get reduced, sometimes greatly reduced,
infection."The disease is caused by the bacterium V. cholerae that attaches itself to tiny, water-borne animals called copepods. The bacteria collect around the mouths and on the egg casings of female copepods, said Colwell, and the bacteria and copepods seem to have developed a mutually beneficial relationship. The animals offer transportation to the bacteria, which in turn help rupture the egg casings of the females so that they can disperse their ova."
http://www.hsph.harvard.edu/ats/Apr28/
Reduced load applies to Giardia too. If you only ingest one or two cysts you are unlikely
to get the disease. That's why drinking from huge glacial rivers and fresh sierra snow pack is of little concern due to dilution.Sep 2, 2011 at 2:23 pm #1775496As posted on the recent gun thread and updated to this thread.
"The need to carry (a water filter) in the city or the wilderness just reaks of fear. I realize others see it different, but I see it as a sign of fear."
Sep 2, 2011 at 2:27 pm #1775497The closest designated wilderness area to me has sketchy water at best, that is, if it has flowing water at all.
Sep 2, 2011 at 3:39 pm #1775518I have long felt that water safety is a classic "YMMV" kind of deal. For those of us in the wet part of the West it isn't a big issue – I'll say this – I fear water being tainted from old mines over anything else – such as high levels of (Jeez, it won't let me post a-r-s-e-n-i-c, it says it is a profanity????), lead, etc – which in some areas is a a real concern. But as for eggs….not so much.
Sep 2, 2011 at 3:54 pm #1775526AnonymousInactive"Jeez, it won't let me post a-r-s-e-n-i-c, it says it is a profanity????), lead,"
Careful, Sarah. Lead is a four letter word. ;)
Sep 2, 2011 at 4:07 pm #1775528AnonymousInactive"You filter out the host and the host's food, which are much larger. When you reduce the
total load (number of things being ingested) you get reduced, sometimes greatly reduced,
infection."The word "sometimes", when applied to removing a nasty like cholera makes me even more skeptical.
"The disease is caused by the bacterium V. cholerae that attaches itself to tiny, water-borne animals called copepods. The bacteria collect around the mouths and on the egg casings of female copepods, said Colwell, and the bacteria and copepods seem to have developed a mutually beneficial relationship. The animals offer transportation to the bacteria, which in turn help rupture the egg casings of the females so that they can disperse their ova."
This, and the quote above, would imply there are no free floating cholera bacteria in a water source. If fecal material is discharged into a water source and there are no copepods to attach to, it would seem there is a reasonable chance of trying to filter out 1-5 micron bacteria with a handkerchief or sari. That is not a chance I would want to take, given the potential consequences, particularly when it is so easy to carry a filter or other treatment device/chemical. The thing that bothers me here is the imprecision of the concept.
Sep 2, 2011 at 4:14 pm #1775531AnonymousInactive"The need to carry (a water filter) in the city or the wilderness just reaks of fear. I realize others see it different, but I see it as a sign of fear."
Depending on the city or "wilderness" involved, fear can be a very healthy emotion.
as I think anybody who has ever had the pleasure of contracting a serious GI infection will agree. For those of you who have not experienced the rapture, by all means place your trust in a folded hanky when treating water potentially infested with cholera. I'm sure there are some tiny lil' critters floating around And don't forget to let us know how it turned out. If you survive. -
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