I probably have Giardia.. and it’s no fun :-(

[Buck Nelson]

One of the very best studies is "Medical risks of wilderness hiking"

http://www.ncbi.nlm.nih.gov/pubmed/12681456

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…

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.

[Greg Mihalik]

"The risk of gastrointestinal illness can also be reduced by maintaining personal hygiene practices and cleaning cookware."

That Is the common belief, but has it really been tested?

As mentioned above, What can grow in a pot overnight that doesn't get resolved with the next boil?"

And from what "d k" has said, anal-to-mouth self-infection hasn't been substantiated.

Personal hygiene and cleanliness in the kitchen seems like common sense, but the question of it's effectiveness is still in question.

[Marko Botsaris]

I always assumed this meant inoculating your food with the bugs from dirt you picked up on the trail.

[Greg Mihalik]

My food is in my pack, in bags, until it get dumped into boiling water.

You got ham hock swinging from your pack?

;-)

Oh, you mean dirty hands handling the food….

Well maybe washing away tetnus Is a good idea.

Muscular spasms (specifically opisthotonos) in a patient suffering from tetanus.
Painting by Sir Charles Bell, 1809.

[d k]

Did you read the same article I did, Greg? It had that picture too…

"Clostridium tetani is the causative agent of tetanus. … Carrier rates in humans vary from 0 to 25%, and the organism is thought to be a transient member of the flora whose presence depends upon ingestion. The disease stems not from invasive infection but from a potent neurotoxin (tetanus toxin or tetanospasmin) produced when spores germinate and vegetative cells grow after gaining access to wounds. The organism multiplies locally and symptoms appear remote from the infection site."

So in other words, you should wash your hands to keep tetanus out of your wounds (more important than keeping it out of your food! though if you keep it off your food it's less likely that you will be carrying it inside you to a later date when you will have additional chances of getting it in your wounds). My thinking (this is opinion, haven't seen this spelled out anywhere) is that handwashing on trips is probably more important in terms of washing away any disease-causing organisms you've picked up externally, and perhaps to keep any of your own internal flora from getting into foods like cheese that you carry for a number of days that can foster bacterial toxin production. Also to keep your internal flora away from your companions in case you are incubating a disease-causing strain of bacteria, or even a cold (adenoviruses and others are shed in feces too).

[Valerie E]

And getting a tetanus shot (or a booster) is probably a pretty good idea, too…

[Anonymous]

"And getting a tetanus shot (or a booster) is probably a pretty good idea, too…"

+1 big time! All the washing in the world isn't going to prevent tetanus being carried into a puncture wound, which is the way a lot of tetanus infections used to be incurred, stepping on a nail, thorn, etc.

[d k]

+1 on the vaccine! I should have said that…

[Daniel Pittman]

I had tetanus once. It's no joke. Went to the doctor with a sore throat and back spasms. Diagnosed with strep throat, and about to be discharged when a violent back spasm hit. The doctor said, "Hold on a minute, let's do one more test…" then stuck a tongue depressor in the back of my throat. I chomped down so hard it made the doctor jump! Apparently, a symptom of tetanus is that your gag reflex is replaced by a chomp reflex.

Treatment was pretty easy, IV antitoxin, oral antifungal, and a big-ass bottle of Valium.

The doctor asked if I had been exposed to rusty metal, or had any puncture wounds. I said, "I'm a bicycle mechanic, so yeah. Every damned day!"

[John S.]

No mention of confirmed diagnosis.

[James Couch]

In addition to the study Buck noted upthread here are a few more:

http://rendezvous.nols.edu/files/Curriculum/research_projects/Risk%20Management%20Reports/Medical%20Incidents%20and%20Evacuations%20on%20Wilderness%20Expeditions.pdf

http://www.ijidonline.com/article/S1201-9712%2800%2990102-4/abstract

It is also good to note the Cryptosporidium can lso cause simimilar gastro distress and crytpto can survive outside of water for much longer periods of time than does Giardia, including on your hands after being around infected water.

[Kevin Burton]

Hey guys. So just a follow up here.

After about 1.5 weeks I was better. NO official diagnosis. For various reasons the logistics around getting an official diagnosis were somewhat complicated.

I went on Metronidazole and within 72 hours I was fine. Well, much much better.

http://en.wikipedia.org/wiki/Metronidazole

Symptoms were severe lethargy, bloating, LOTS of burping (like non stop), green stool, and loss of appetite. I didn't really eat for a good 2-3 days. Normally about half the volume of food per day.

One trick I learned to make me feel better was just to rock back and forth from a horizontal to vertical position. That helped with gas and bloating.

Definitely NOT fun. Screwed up my plans as well as I was going to go back to the woods.

My doctor felt pretty confident that the burping and green stool were giardia so he just gave me meds without the test. I didn't ask him but apparently they are somewhat pricey and since he felt confident I figured I would save the money.

[John S.]

Thanks for the follow up Kevin. Glad you are better. I'd imagine many cases of suspected giardia are treated with meds and no lab test to confirm.

[David Thomas]

>"The doctor asked if I had been exposed to rusty metal, or had any puncture wounds."

Rusty nails are kind of a red herring. It's not that the tetanus bacterium Clostridium tetani is a iron-oxidizing species (there are iron-oxidizing bacteria, but no human pathogens that I know of). But rusty metal has been in moist conditions, often in the ground, and can be sharp and strong enough to cause a deep (anaerobic) puncture wound. And rusty metal has a lot of small pores and therefore more potential for delivering bacteria deep into your tissues. So, yes, many people have gotten tetanus from a "rusty" nail, but any fomite (an inanimate object that transmits an infection) could serve that purpose if it had been exposed to soil containing the bacteria (soil with livestock manure is even higher risk).

[Cameron Habib]

Quite a lot of information in this thread, some of it good, some of it bad; hopefully I can help to shed a bit of light. To preface, I’m a molecular microbiologist, with particular focus on infectious and emerging disease – in simple terms, I perform the type of research those CDC reports are based on. Some quick notes I typed up, hopefully someone finds this of use or interest.

There are two basic categories, and several subcategories, of contaminants you should be concerned with when it comes to drinking water:

1) Biologicals

1.1) Viral – Viral contamination is extremely prevalent in nature. Thankfully, most of these viruses are known as bacteriophage, and infect only prokaryotic (bacterial) cells. These cannot infect eukaryotic organisms (for reasons I can specific if anyone is interested), and as such, pose little threat to human life. Little does not mean none however. As humans, we are inhabited by thousands to millions of different bacterial species, many of which, while symbiotic in nature, are only a handful of genes away from virulence. The perhaps best known example of this is one of the most common soil bacterias, present in almost all human gut micro biomes, Bacillus subtilis. With the addition of a few very well known and studied genes, it quickly goes from a harmless organism, to something called B. anthracis, which many of you will recognize as the infamous bioterrorism agent. While unlikely the necessary genes could be transferred via bacteriophage (called horizontal transfer) for this kind of change to occur, it isn’t impossible. Some caution should be taken against viral contamination to prevent mutation of human flora and microbiome mutations resulting in increased virulence.

Depending on the nature of the viral strain, boiling can be insufficient to destroy. DNA damage (due to UV light or other method), chemical reagents (bleach), biological reagents (proteolysis), and in some cases autoclaving (pressurized super heated water) are the only options for sterility. As viruses are smaller than the filter pore size of 0.2uM, these devises are ineffective against viral particles. Your best defense against these in the field would be a UV pen or chemical agent.

1.2) Bacterial / Protozoa – It is a commonly held standard that a pore size of 0.2uM is sufficient to filter out biological contamination from liquid samples. When preparing chemical solutions in a research lab, a filtration device with this pore size will be used to sterilize material sufficient to achieve reaction grade biologicals. While there do exist both bacterial cells (known as ultramicrobacteria) as well as bacterial spores smaller than 0.2uM, though not Protozoa to the best of my knowledge. These are generally uncommon however, and to the best of my knowledge, none of yet to be identified with mammalian pathogenicity.

Heat is often enough to kill most biological samples, though boiling (as defined for this purpose to be at 100C though does change with pressure) can be insufficient in some cases. One of the most important bacterial species in science, Thermus aquaticus, part of a group of organisms known as thermophiles, thrive in high temperatures, often in excess of 80C. Other species of this group have been observed to tolerate up to 122C for extended periods. As someone previously mentioned, it is not only the temperature, but the duration of time as well that determines survivability for organisms. Any good molecular gastronomy cookbook (Modernist Cuisine being my favorite) will have kill curves showing time plotted against temperature to determine the correct conditions to adequately decontaminate (not sterilize) material. Chemical agents will have a similar effect as heat, with most being easily effected, but some having limited efficacy. Bleach is the most common compound used in laboratory settings, though some species can survive for prolonged periods in high concentrations of chlorine. Those are again rare, but highly pathogenetic when encountered.

Typically speaking, 30 minutes at 121C is considered sterile for liquid samples. For common drinking water contaminants, contaminants should be killed fairly quickly at 100C; exact times and temperature are of course entirely dependent on what you're trying to kill though. Keep in mind however, bacteria that posses the ability to infect a mammalian host, which an internal body temperature somewhere around 36C, are optimized to grow at that temperature (which is why they choice the human as a host), and are unlikely to be able to survive a wide enough range of temperatures to including 100C for any amount of time.

1.3) Protein based – These are the deadliest of all, and least common. Formally known as “prions,” these are mis-folded proteins, that upon contact with normal state proteins, auto-induce their transition to disease state. Prions are virtually impossible to remove by filtration, due to their small size, unaffected by heat, due to their hyper-stable state, and often cannot be dissolved by chemical means. There are reports of one of the more famous prions, bovine spongiform encephalopathy (otherwise known as Mad Cow), infecting a farm with farmers reacting by killing the cows, burning the property, and abandoning it for decades, only to come back and find the prion still exists. There is no cure, no test for contamination, and no real way to remove them via field or even lab setting. Current protocols call for several treatments of gaseous solvent to be passed over the contaminant, along with a number of other measures, and even then, many have proven ineffective.

2) Non-biologicals

I won’t go into great detail here, but this category includes everything from toxins produced by biological threats (such as the toxin produced by Clostridium botulinum), to nerve agents, poisons, etc. These can typically be filtered out by activated charcoal, or other distillation methods.

Now, all this said, the best thing to do is just practice common sense. How likely are you to encounter a prion from a clear moving spring along the cost of Maine? How safe is that water just outside the cattle farm to drink? What are the contaminants most common in that area, and where are they typically found? I personally rely on three purification techniques, in this order: a 0.1uM filter (Sawyer Squeeze, not mini), UV SteriPen, and chlorine dioxide (Aquamira). Between the three of them, they can neutralize almost any pathogenic biological contaminant, and certainly all of the more common ones. If a water supply looks clean and unpolluted, I simply use the filter. If I’m unsure, or want extra protection, I treat with UV for a bit, or chlorine dioxide if the volume is larger. Be safe, use common sense, and you should go home happy and healthy.

[Michael Gunderloy]

Thanks for the informed info!

"a 0.1uM filter (Sawyer Squeeze, not mini)" – Why the Squeeze over the Mini?

Has there been any work done in looking at the overall geographic distribution of viruses harmful to man? Wondering if there are regional or seasonal differences that would make it more or less likely to run into viral contamination of water.

[Cameron Habib]

I prefer the standard size as the Mini has less filtering surface area. This reduced area causes the filter to become more easily clogged, causing increased pressure and strain on the pores, which could cause damage, and as a result, allow for microorganisms to pass through. The number of cells required for pathogenicity by certain species of bacteria can be amazingly small, and as such, even a minor defect in a filtering apparatus can have drastic impacts. In short, it's a type of insurance policy.

I'm not sure about the distribution, as that would be more of a Public Health matter, though I'm sure it has been mapped out before.

[Buck Nelson]

I find the NOLS information very interesting because they are engaging in outdoor activities like us and seem to keep some good records. Thanks for the link, Jim. I'd like to note that NOLS has shown that water treatment, hygiene and clean cookware has yielded outstanding results for gastrointestinal health.

The conclusions of the oft-cited Welch paper are NOT accepted by the CDC, FDA, EPA, Mayo clinic or any other major public health organization of which I'm aware. I've outlined some of the reasons his paper has been refuted by mainstream science.

Backpacker Giardia: Debunking a Skeptical Paper

The CDC has one of the best overviews of giardiasis, including prevention.

The EPAs Giardia: Drinking Water Health Advisory is a good source of information for both underlying data and studies as well as conclusions. It has information on the prevalence of giardia cysts in backcountry water, the effectiveness of chlorine and other forms of disinfection, immunity, and many other oft-discussed topics. Well worth a read-through for those interested in the topic!

[Jerry Adams]

I assume you don't mind if I post a link to your site elsewhere

[Buck Nelson]

That would be fine Jerry.

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