Outbreak of Giardiasis Associated with Drinking Surface Water Along a Hiking Trail [Aquamira]

[Buck Nelson]

This is an interesting paper to me because it supports one of my conclusions, that backcountry water is a significant risk for giardiasis, while putting into question another of my convictions, that, used as directed, Aquamira is fairly dependable for treating water that might hold giardia cysts.

RESULTS: Eleven campers were interviewed. Six cases were identified, including two laboratory-confirmed with Giardia. The group primarily used chlorine dioxide water treatment drops to treat their water; none reported drinking untreated surface water. The median amount of time campers reported usually waiting between treatment with the drops and consumption of water was 30 minutes (range, 20 to 45 minutes). The length of time waited did not differ significantly between cases and controls. The package instructions specify that water should stand 15 or 30 minutes before use depending on water temperature or turbidity; however, the label indicates the drops kill odor causing bacteria but does not make a claim that the product kills Giardia or other pathogens. The manufacturer of the drops was contacted and reported that the product requires 4 hours of contact time to inactivate Giardia cysts. Swimming at any water body was not significantly associated with illness.

CONCLUSIONS: This was a waterborne outbreak of giardiasis associated with drinking surface water at multiple points along a hiking trail. Chlorine dioxide can be an effective pathogen reduction method; however, the product used by the campers is not certified for pathogen reduction, although it is frequently marketed as such. Consequently, while the campers followed the package instructions, the treatment appears to have been ineffective at inactivating Giardia cysts in the water. Future efforts to prevent illness from the consumption of backcountry water need to include creation of clear guidelines recreationalists can use to choose effective water treatment methods.

https://cste.confex.com/cste/2015/webprogram/Paper4528.html

[Cayenne Redmonk]

I thought that it was common knowledge that the contact to treat giardia was 4hours, and not the time quoted for treating clean warm water for bacterial contamination.

I, for one, am not at all surprised that following the popular 'Do this quick treatment like I do' fails when the water actually requires treatment.

Most people choose not to read. Even with a link shown in plain text, most won't take the time to manually navigate to the page. Even if the package said clearly 4 hours, most people wouldn't read it because they heard 15 minutes is close enough for the super clean water they will encounter.

[Justin Baker]

What trail?

4 hours contact time just to drink the water is ridiculous, no way I would ever choose that method.

[Roger Caffin]

> 4 hours contact time just to drink the water is ridiculous,
That's why many of us have switched to UV treatment. NO waiting time.

Cheers

[Hikin’ Jim]

UV treatment is good, unless you're in an area that has cloudy water. In clear water, particularly if you filter out the "floaties", you should have good results.

The other problem with chemical treatment is the taste. Barf. Chlorine dioxide's flavor is marginally more tolerable than iodine, but it's still bad.

I guess the advantage of chemical treatment is that it is less vulnerable to breakage and dead batteries than a UV device.

Eleven campers were interviewed. Six cases were identified, including two laboratory-confirmed with Giardia.

Interesting that roughly half the campers did not get giardiasis. This is consistent with what I have read elsewhere that Giardia doesn't affect approximately half the adult population. Not that I want to engage in direct experimentation to determine which half I fall into.

HJ
Adventures In Stoving
Hikin' Jim's Blog

[HkNewman]

There is a need to read the instructions. UV is looking better

[Chad B]

Did they research hygiene practices of the group while on trail?

[Jerry Adams]

> 4 hours contact time just to drink the water is ridiculous,

That's why many of us have switched to Sawyer Squeeze – doesn't rely on complicated electronic device with batteries : )

[Buck Nelson]

The McNett/Aquamira people say: "Under worse case scenarios (really cold and turbid water), it could take up to 4 hours to effectively remove Cryptosporidium"
https://mcnett.zendesk.com/entries/26536537-Aquamira-Wait-Times [Giardia is easier to kill]

McNett hasn't been given permission by the EPA to claim the drops will kill giardia and crpyto, even though they can. So the directions for the drops are for killing viruses and bacteria. Most people will naturally believe that 15-30 minutes is enough for giardia as well and it USUALLY will be.

Check out the in the following thread. Under "normal" conditions chlorine dioxide (Aquamira drops or tablets) should kill 99.9% of giardia in 30 minutes. http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/64484/index.html?mb_sort=desc

It seems pretty clear that along the Superior Hiking Trail something unusual was happening. Aquamira is widely used, giardia is widespread although USUALLY in low concentrations. I'm guessing there were some beaver ponds or other water sources that had really high concentrations of cysts, 1,000 per liter would be possible. Perhaps the water was unusually cold and turbid as well. This paper would seem to reinforce the findings that standard wait times are not enough in worst case scenarios.

"Did they research hygiene practices of the group while on trail?"

They don't directly address that issue but say An outbreak investigation was initiated to determine if there was an association between a water source and illness.

METHODS: Epidemiologists from MDH interviewed campers to obtain information on drinking water sources and treatment, swimming exposures, and illness history

So it would seem they looked at whether someone brought giardia in with the group.

Although it's probably happened, as far as I know there has never been a single epidemiologist-verified case of backcountry giardia (let alone a backcountry giardiasis outbreak) attributed to poor hygiene.

[Scott S]

Here's a textbook example of a study you should ignore.

– miniscule sample size
– not published in a reputable, peer-reviewed journal (it's a conference proceedings)
– lack of controls of any kind

I'm not saying that the researchers are wrong. But this is not the sort of science on which anyone should be basing their water treatment decisions. There are loads of better sources out there.

[Rick Reno]

You're right; that "study" won't pass muster in many peer-reviewed journals. Still, it's pretty compelling anecdotal evidence. "I talked to 11people who used Aqua Mira and thought they were doing it right. Over half of them got giardia."

OK, they got my attention… Sawyer squeeze for me!

[Jerry Adams]

maybe they were all using the same package of bad Aqua Mira

maybe they all used the same, broken clock to measure time

maybe they all took from an exceptionally contaminated source of water

yet, Squeeze (or Steripen) is so lightweight and easy, may as well use it. Chlorine takes too long, so you have to carry extra water, which weighs way more than the Squeeze (Steripen)

[Greg Mihalik]

My Katadyn Hiker pump/filter weighs 14 ounces when wet. Still lighter than carrying water for 4 hours.

[Justin Baker]

Greg, what's wrong with a gravity filter like the sawyer squeeze?

[Kenneth Keating]

Did they all eat at the same restaurant afterward? Did someone forget to use chemical treatment? Were they using multiple bottles and one bottle got double the dosage and one bottle got none?

[Greg Mihalik]

^^^

Nothing, if you have "dippable" water. We use them in the Boundary waters.
When I'm fishing I use a Squeeze.

But often times I'm pumping water out a gravel seep or mudhole or hardrock rivulet that you couldn't dip.

And it's faster than gravity. In the time it takes to set up a gravity system, I can be done pumping and gone.

It's familiarity and environment.

But the point I was making above is that even a heavy pump is a better option than a 2 liter carry for a couple of hours.

[Jim Colten]

Let's start with What follows isn't just MN talking. It is based on info from folks I trust to be objective to a fault (if there can be fault in that). Also personal experience.

MDH's epidemiologists have a stellar reputation both here in the USA and internationally. That isn't to say that a mistaken conclusion is impossible. But they know how to avoid the kind of errors and oversights that have been speculated about above and their methodologies are designed to avoid them.

Beyond the opinion of the folks I know, I had the "pleasure" of being visited by big G and also STEC during the same calendar year (2009). Their patient interview process is exhaustive … d*mn near exhausting! Not only that, but it was obvious that their left hand(s) know what their right hand(s) are doing. The STEC interview included numerous questions to confirm that this was an infection separate from the earlier Giardia AND to evaluate the strength of the information saying it was separate. That was just OCD thoroughness … they had conclusive lab results. They also followed up with a call after every stool sample found positive during the months long battle between my immune system and STEC … just to confirm that this was part of a single ongoing infection.

To repeat … their conclusion about this more recent event could possibly be incorrect … but I wouldn't bet the farm on it.

[Arthur]

UV is good on paper, at home. In my experience, heavy, not great with tubid water, and it stopped working when i dropped it a measly 10 inches. I think Sawyer has figured filtering out, finally.
Art

[BlackHatGuy]

"To repeat … their conclusion about this more recent event could possibly be incorrect … but I wouldn't bet the farm on it."

Thanks Jim, good to know.

[Jim Colten]

@Art: I think Sawyer has figured filtering out, finally.

That would be nice. I've had too much problems with filters clogging to feel comfortable with them. But maybe there has been progress in that regard … been a decade since I used one.

UV is good on paper, at home. In my experience, heavy, not great with tubid water

I had a recent discussion with a QC guy from our local water treatment plant. He wouldn't endorse any treatment method as risk free. He was taking scouts into the BWCAW and was gonna use filtration AND UV. Turbidity was high on his list of obstacles … but not only suspended solids, dissolved organics too … apparently carbon-to-carbon bonds absorb UV in the wavelengths used to sterilize water.

@Doug: Ya know … I don't think I can guaranty that a mouse hadn't p**d or p**ped in the snow we melted for water, he-he.

[Elliott Wolin]

Best advice I've heard came from an AquaMira salesman. He said to use ClO2 drops/tablets to kill bacteria and other easy stuff, then use a Frontier Straw to filter out the big stuff, i.e. Giardia and Crytopsporidium. With this technique you don't have to wait very long, maybe a few minutes, as the ClO2 kills the small stuff quickly and the straw filters out the rest.

I used this system for a while, but recently went to UV. But I bring some tablets and a Frontier straw just in case (along with extra batteries). Belt and suspenders…

[Andrew U]

Seems like user error. I've used aquamira in populated areas many times. Never gotten sick. If the water is questionable, I wait the full 4 hours or even overnight. This is a time tested, proven method for treating water. Some public municipalities use chlorine dioxide for water treatment.

Just because a few people get sick doesn't mean the product is defective or misleading consumers about effectiveness.

Some people are stupid. Stupid people have a harder time getting through life. This is not new news.

[Greg Mihalik]

Some people recommend that 4 hours isn't necessary, and some people believe them.

Go figure.

[Elliott Wolin]

I also treat large quantities of water overnight at typically half-dose in a large platypus. The dose-time relationship is mostly linear (within limits), e.g. doubling the time means you can halve the dose.

[Andrew U]

"Some people recommend that 4 hours isn't necessary, and some people believe them."

True, and many people use aquamira for only 30 minutes, myself included, and don't get sick. But presumably those people are adept at identifying quality of water sources and act accordingly.

Claiming that an isolated incident is proof of a product's ineffectiveness, when the people admit to using the product outside of the manufacturer's recommended guidelines, is rediculous, regardless of what "the other guy" says to do.

It's like when someone buys a truck or large SUV and then complains about the crappy gas mileage. They should have known the tech specs of the vehicle before purchasing it. Same situation here. Aquamira has never once claimed that their product will kill cysts in only a 30 minute treatment window. Expecting a product to do something it never claims to do is unfair.

And claiming ignorance is NEVER an acceptable excuse.

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