Do you filter?

Giardia transmission in the backcountry is usually between hikers — fecal oral transmission — not from the water supply. Subject of much debate until fairly recently. Livestock can contaminate streams with giardia but this is probably inconsequential. Take same precautions when handling animal fe ces (that's profanity, WTF) as human fe ces. Common sense. Also, more prevalent among g ay (that's profanity too!) men. I will let you consult other sources (perhaps the CDC website) if you are interested.

Giardia is present often at fairly high levels in many municipal water supplies. Vail used to be the giardia capital but the city has since overhauled its water purification system. The Sydney water supply often contains high levels of Giarda. Thus many of us are immune from previous exposure.

Giardia infection is very often completely asymptomatic. Symptoms when they occur are generally cramping and flatulence. Rarely causes much water loss or dehydration. Onset is usually 10 days to 2 weeks after exposure. If you drink some "bad" water and wake up the next day with diarrhea, it's not giardia! Giardia is generally regarded as a self-limiting illness (no treatment indicated) but drugs are often used. Effectively treated with tinidazole (single dose!) or metronidazole. Testing stool for ova and parasites is futile. Treatment based on suspicion.

Most surefire way is boiling — for giardia just bringing the water to a boil should be enough. Personally, I'm inclined to filter or boil. But I'm a bit prissy about these things.

Depends on where you're going. Wouldn't be terribly freaked out about Giardia in the water. It's quite likely in the water you drink at home. It's certainly in swimming pools. Illness is often asymptomatic or very mild. Poses a problem in immunocompromised. If you have AIDS, should boil at home too.

If you are traveling to places where amoebic dysentery is a problem, yes, that's something to get excited about.

We had one literally just about catch on fire this summer (hey Sarbar!). Was not a first generation one, but a current one. Something about the battery – either the wrong kind or installed incorrectly. It was a borrowed unit.

As for how it works? It somehow scrables the DNA of the critters in your water? Or something like that.

Hi Hartley

> The Sydney water supply often contains high levels of Giarda
?? Are you sure about this? Or are you thinking of Crypto? I know that latter does occur in the pipes at times.

Doesn't worry us anyhow: we drink chlorine-free rainwater from our own tanks.

Cheers

Hi Dicentra

> As for how it works? It somehow scrables the DNA of the critters in your water?
Roughly speaking, yes. It scrambles the DNA and cellular structure such that the individual bugs can't multiply.

> We had one literally just about catch on fire this summer (hey Sarbar!). Was not a first
> generation one, but a current one. Something about the battery – either the wrong kind
> or installed incorrectly. It was a borrowed unit.
Would you call this a device fault or an operator fault?

Cheers

According to the numbers from last year, sounds like the levels of crypto and giardia in sydney were quite low.

http://www.sca.nsw.gov.au/publications/awqmr08/monop/crypto

From time to time there have been high levels with advisories to boil. If I remember correctly, I think these cysts are quite hardy.

Both crypto and giardia are present in varying amounts at varying times in water supplies throughout the US and elsewhere. Most of us have been exposed. The concentrations in mountain streams are probably not terribly worrisome. Take the water upstream from campgrounds, etc. I boil/filter but cheat when I'm real thirsty. Obviously, If I were in a place where serious water-borne pathogens exist, I wouldn't be quite so causal.

As has been pointed out earlier, backcountry transmission is overwhelmingly fecal-oral between campers — much larger dose than you find in water. BTW, Giardia is rampant in day care centers.

Where we travel there are lots of bigger critters in the water… and lots of beaver dams which was most likely how I contracted giardia. I found out, after the fact, that our friend had a crack in his filter on the trip. Since that time I refuse to let anyone pump water for me – I do it myself. I'm a little more than fastidious about hand and body sanitization as well… to the point of being somewhat ocd about it.

Early in October I was on a hike during which I only used Pur. Just over a week after returning I was hit with giardia. Severe stomach cramping, gaseous, extreme weakness, and I had to force liquids and some food down for several days. Looking back at the conditions, I had previously thought that the water I was using was good enough to not even require purification. I used the correct amount of MicroPur, 1 tablet per liter, and gave it ample time to work. The only answer I could come up with was that I paid little attention to the rims of the generic bottles that I was dipping into the water to fill. The episode has almost scared me back to using a filter, but hopefully carefully cleaning the thread portion of the bottles the next time will solve the problem.

"Chemicals? filters don't filter chemicals either. Which is why one needs to be aware of mines, industrial installations, and agriculture in your area before drinking up."

"Neither chemicals nor many other filters do much to remove dissolved chemical either! Activated carbon cores can help, but don't rely on them for your health!"

Charcoal removes a vast array of organic chemicals. Or, infinitely more than the Steripen. To not use it because it doesn't remove 100% is like not wearing seatbelts because they don't prevent 100% of deaths, or not filtering because most common filters don't remove viruses. It's about taking reasonable measures to reduce risk, not risk elimination.

Also, I'm not sure that misuse of the Steripen is exculpatory if the design is conducive to it.

"Charcoal removes a vast array of organic chemicals. Or, infinitely more than the Steripen. To not use it because it doesn't remove 100% is like not wearing seatbelts because they don't prevent 100% of deaths, or not filtering because most common filters don't remove viruses. It's about taking reasonable measures to reduce risk, not risk elimination."

NO ONE SAID that you shouldn't use a filter because it doesn't remove chemicals. I SAY you should always be aware of the risks in the area you hike in and act accordingly. If there are sources other than the ones downstream of the mine, power plant, sawmill, whatever, those are the sources you should shoot for even if it means going an extra few miles – DON'T TAKE RISKS IF YOU DON"T HAVE TO. There are a lot of mines marked on my maps – I don't filter down the hill from them! I don't drink down the hill from them! You do the same and we'll be safe! I don't want giardia, but I also don't want to get sick from chemicals that the filter won't remove. EASY to avoid what you are aware of, right?

http://travel.latimes.com/articles/la-os-giardia26jul26

"The threat is comparable to the chances of beachgoers being attacked by a shark, according to University of Cincinnati researchers who studied the danger giardia poses to backpackers, namely "an extraordinarily rare event to which the public and the press have seemingly devoted inappropriate attention."

Time for me to shut up and hike!

"The threat is comparable to the chances of beachgoers being attacked by a shark, according to University of Cincinnati researchers who studied the danger giardia poses to backpackers"

Excellent point. Probability helps us compare threats or weigh a threat against the cost of prophylaxis. In that respect, my Sawyer has a lifetime guarantee which minimizes dollar cost. Used as a gravity filter, it does the work leaving me to do other things which minimizes the personal cost and it eliminates other pathogens as well as giardia; a bonus!

Check this article on Giardia out.

http://erikschlimmer.com/pdf/GiardiaMyth-Buster.pdf

Tony

> Also, I'm not sure that misuse of the Steripen is exculpatory if the design is conducive to it.

Equally, I'm not sure that misuse of a V8 car is exculpatory if the design is conducive to it.

Cheers

> http://erikschlimmer.com/pdf/GiardiaMyth-Buster.pdf

That's the trouble with evidence-based research – it upsets the vendors who have a vested interest in your wallet.

Yep – fecal-oral transmission for 99% of problems. (Contaminated food for the remaining 1%.) WASH YOUR HANDS! And don't trust others … especially in Asia.

We gave up treating most of our water a year ago. The only time we still treat is when we know we are downstream of farmed animals. (A lot of cows, sheep and goats in Europe.)

Cheers

"Yep – fecal-oral transmission for 99% of problems. (Contaminated food for the remaining 1%.) WASH YOUR HANDS! And don't trust others … especially in Asia.

I guess I must be the exception that proves the rule. I contracted both bacillary and amoebic dysentery in Asia, Afghanistan and India respectively. Very little water is safe in Asia, IME. Here in the US, the picture is less clear because fecal-oral contaimination is clearly a vector as well. This is not to say giardia or other pathogens are not a problem is some areas here. My own protocol is to first take Immodium; If that is ineffective take an antibiotic effective for gastro intestinal bacteria; If that is ineffective, it's probably a parasite and it's time to have a stool sample analyzed. I haven't had to employ this protocol so far while backpacking, partly because I filter in suspect areas and partly, I suppose, because there aren't any pathogens present in significant quanties in areas where I don't filter. Or even where I do filter for all I know.

"Giardia transmission in the backcountry is usually between hikers — fecal oral transmission — not from the water supply."

The question then arises: where did the transmitting backpacker acquire giardia?

How was it determined that transmission is usually between hikers? I'm genuinely curious as to how this conclusion was reached. Seems like it would be very difficult to figure this out, given the nature of backpacking.

Transmission is fecal oral. Many if not most people who have giardia do not know they have it. They basically contaminate their companions' food with their crap. Same way it spreads in day care centers. There are other variations on this theme but I will leave that to the reader's imagination and google.

Giardia diagnosis is difficult. You need 3 stool samples from separate dumps. You need to sift through the stuff looking for ova and parasites. It's messy and expensive and rarely done. If you think giardia is a possibility you give tinidazole (single dose, but only recently becoming popular in US) or metronidazole (must be taken 10 days or so). These drugs are relatively safe though should avoid alcohol. So just because you were treated for Giardia does't mean you had Giardia.

Just because various organisms are present in the water you drink does not mean they will cause infection.

While we're talking about fecal-oral transmission, the Hep A vaccine is probably not a bad idea. I am very wary of vaccines, picking and choosing carefully. Of course, the childhood vaccines and current tetanus are no brainers. Hep B in a healthcare environment is a no brainer, IMO. Yes, Hep A is rarely a serious illness but the vaccine is a component vaccine and should be very safe.

Thank god I can drop all forms of water purification. I am more likely to get sick If I use any sort of water treatment than if I use none at all. Please see chart from pdf.

How Often they Treated Water – Percent who got sick

Always – 21%
Usually – 28%
Sometimes – 29%
Never – 20%

I also think it is very funny that there were recent threads questioning pot washers and poking fun at soap users. According to this document, wouldn't those two actions be of utmost importance.

It also bothers me that this whole discussion is revolving around giardia and ignoring other bugs and contaminants that can exist in water.

Ha,
I'm glad to see that no one has come up with the number 1 reason on how Giardia is passed upon you from your best friends butt.

It's what mama always told you to get your finger out of.

So there are other things you shouldn't do out in the wilderness other than not wash your hands

Hartley,

How did you learn so much about medical issues? I am not being contentious; I am being complimentary.

So it sounds like some people are asymptomatic carriers for giardia? That would make a lot of sense given what’s been discussed here and elsewhere about people’s gut flora:
Seed Magazine: The Body Politic

> where did the transmitting backpacker acquire giardia?
Ah good question.

My understanding is that the bugs can reside in several parts of your 'guts'. There's your stomach, your upper intestines and your lower intestines. (Medicos, please correct if necessary, but allow for some 'gross' simplification!)

Bugs in your lower intestine apparently don't do so much harm to you, but bugs in the upper intestine and in your stomach do create more serious problems. So … when you get some new bugs via your hands and mouth, they first go to your stomach and your upper intestines. There they multiply and create big trouble. Some of them secrete toxins through the gut wall into your blood-stream; others just latch onto the gut wall and suck your blood – and irritate the hell out of the gut lining.

They subsequently migrate downwards to your lower intestines, the lining of which is a bit more robust and can withstand the bugs a bit better. They can persist here even after they have been cleared out of your more sensitive areas.

So – you might be carrying some of these bugs in your lower intestines and be an asymptomatic carrier – you have the bugs but you don't have any symptoms. But because you have the bugs, you can transmit them to someone else's mouth etc. This is basically how these bugs survive after all, and is extremely common.

Doubtful? Think about E coli. Everyone has this in their bowels, and it is harmless there. It can't progress back up towards your stomach: there are valves to prevent it. But it can cycle around outside your body into your mouth, giving you various forms of gastro etc.

Why is Giardia (and others) very common in Day Care centres? Think about the toilet habits and nappies there …

Cheers

I'm skeptical of that U. of Cincinnati study ( survey of 48 of the 50 state health departments).
From the first state I searched (VT):
"How do people get giardia?
People and animals infected with giardia pass it in their stool. People become infected:

directly by hand-to-mouth transfer from the stool of an infected person. That is, hands can be soiled when using the toilet. If hands are not thoroughly washed, the giardia can be transferred to food, drink or items handled or eaten by another person.

indirectly by swallowing water that has been contaminated with stool that contains giardia (when swimming in ponds, drinking from streams, etc.).

What are common sources of giardia?

drinking contaminated water from streams, rivers, springs and ponds

infected household and day care contacts, especially children in diapers (See Giardiasis in Day Care Centers, also available from the Health Department.)

swimming in untreated surface water, such as wading pools, ponds, rivers, streams or lakes

private water systems (wells or springs) that are not correctly installed or maintained"

Worcester, MA, had cryptosporidium in the drinking water while I lived there. The reservoir area is the sort of place that you would assume by looking at it that the water is safe without treatment.

Probably most diarrheal illness is bacterial (E. Coli, etc.). Probably most is from poor sanitation or food rather than water. However, it seems likely to me that some is from drinking water. The majority of AT through hikers get diarrhea

"Giardia diagnosis is difficult. You need 3 stool samples from separate dumps. You need to sift through the stuff looking for ova and parasites. It's messy and expensive and rarely done."

They definitely didn't bother with stool samples when I was sick in India. The doc had me lie down on a table and proceeded to palpate my abdomen gently for a few minutes. "You have amoebic dysentery" he said matter-of-factly. I asked him how he could tell and he said, "Your liver". He prescribed a round of metronidazole(Flagyl)and sent me on my way. It did the trick. I don't know if that diagnostic technique would work in the US where physicians are not as used to diagnosing serious parasitic diseases, but it was much more straightforward than waiting for stool samples to be analyzed. I guess, as Hartley said, if giardia is suspected just go ahead and prescribe metronidazole or tinidazole. Both are supposed to be hard on the liver, though, hence the proscibing of alcohol.

This I can tell you, though: If you ever contract amoebic dysentery, you will never again take a parasite lightly, even a relative wimp like giardia. It's the main reason I filter in suspect areas to this day, mainly the Pacific Northwest in my case.

"So – you might be carrying some of these bugs in your lower intestines and be an asymptomatic carrier – you have the bugs but you don't have any symptoms. But because you have the bugs, you can transmit them to someone else's mouth etc. This is basically how these bugs survive after all, and is extremely common."

I don't doubt this at all as one vector. I do doubt it is the sole vector. In the reading I have done down through the years a recurring theme is the spread of giardia from water source to water source by various animals, voles, beaver, deer, etc, from whence it is acquired by unwary humans. Mountain men in the Rockies called it "beaver fever" and they were by and large a solitary lot unlikely to pick it up by sharing their food. Nor did they treat their water. My point is that humans can also acquire giardia by drinking from contaminated water sources, and probably do. Whether that water source always contained giardia, or had it introduced by an animal or even a careless infected human is, I think, an open question. More or less often than the fecal-oral route, I don't know. Does anybody else know for sure? Have comparative analysis studies been done, or are we extrapolating from studies done in environments like nursing homes? Anybody know for sure? I'd sure love to hear a definitive answer, for my own peace of mind, as well as to satisfy my intellectual curiosity. If fecal-oral is definitively proven to be THE cause of 99% of all giardia cases in the backcountry, I will surely go about treating my water differently.