[pct-l] Water borne diseases--more info about Giardia

[MAXINE WEYANT]

My apologies to the List for
the lengthy post and the inclusion of the 2 prior posts, but I thought it was
necessary to include them for reference.  
This all pertains to the article on Giardia and water sources in the Sierras
posted earlier in the month.  Maxine  

 

Ken, 

Look, my post was never meant
to be a scientific article, so you can quibble about every sentence and say
“Pul-eeze!” all you want, but what really prompted me to write that post was
the way you responded to posts that expressed an opinion which differed from
yours and those expressed in Rockwell’s article.   

 

You responded that “Dr.
Rockwell” was a friend of yours and that you’d discussed his article several
times over the years, as if that was all the proof we needed.  That’s circular reasoning, (and posturing,
some might say.)  By identifying yourself
as a physician and repeatedly referring to your friend as “Dr. Rockwell,” you
may be leading  readers who are casually
skimming the posts to believe that 2 doctors say the research indicates that
most water sources throughout “the Sierras,” a 400 mile long mountain range, is
safe to drink, all the time, and all year long. 
I reviewed his article with some scrutiny and noted that most of his
data is from the 80’s and 90’s.  There
were also a couple of things he said that didn’t seem entirely correct, which led
me to conclude that his field of expertise was in something other than medicine
or microbiology.  So I looked at his
profile and learned that his PhD was in physics or engineering, I forget which.
 I felt the PCT-L readership deserved to
know that, since the both of you were advocating something that may not be safe
for many.   I know you’ve said that people should do what
they’re comfortable with, but you may be unwittingly raising people’s comfort
level.   

 

The people who read this blog
vary from very experienced backpackers to complete novices, some of whom may
not understand all the nuances of “drinking smart” from untreated water
sources.  Not everyone who reads this
blog is in the peak of health and can tolerate high altitudes or easily hike
several miles to a better water source when the creeks north of Sonora Pass
start to dry up and or become cow-trodden.  
In the last 2 months there have been posts from at least 2
Insulin-dependent diabetics, one of whom had to leave the trail twice
(air-lifted once for severe dehydration.) 
I've met a 72 yo man in the Sierras who was on fairly high-dose prednisone
for an auto-immune condition, and last year I met a hiker who was pregnant.   Some people are already physiologically-challenged
and to put them at a higher altitude and then add a little infectious diarrhea and dehydration
could lead to an emergency evacuation, or worse.  And if you’ve done mountain rescues, which I
suspect you have, you know it doesn’t ruin just one person’s day.  

 

As I said before, Professor
Rockwell performed a valuable service by reviewing all that literature and
summarizing it for his readers.  I had no
intention of maligning him.  It’s a great
informal article, and it’s great that he and you and Brick and many others keep
pointing out that most people get sick by ingesting organisms
through improper hand hygiene, not from water. 
 

 

But we should never assume that
the types and numbers of organisms in bodies of water will be the same from one
decade to the next, or one month to the next. 
Microorganisms are constantly showing up in places they didn’t
previously exist, and they evolve constantly to ensure their survival—developing
resistance to harsh conditions, antibiotics, etc.  In natural lakes and streams most bacteria
live in biofilms , which may contain a variety of organisms including viruses
and protozoa.  Biofilms help protect
microorganisms from chemical penetration and allow them to stick to particles
and surfaces.   I don’t intend to get
into a tit-for-tat discussion but I must answer your comment to me about
biofilms.   

 

Ken said:    

 

Your understanding of biofilms is....
lacking.  They have NOTHING to do with
plugging of water filters.  Although you
state that one can read about it in the article, the article was NOT about
filters, and did not mention them, and did not comment on the issue you
mention!

 

The article I referenced
discusses biofilms in over 10 paragraphs and states:  “Filtration devices often clog as a result of
direct filtration of biofilm clusters or slimes, even in apparently clear
water.  We have found that the storage of
filtration devices or long-term use on the trail can result in biofilm growth
in the filter element that can render it useless.  Most backcountry users—and manufacturers—have
long assumed that filter failure is a direct result of filtering silty water…….But
they have ignored the effect of biofilm growth in the filter element, a
more-common-than-not means of filter failure in the absence of significant
silt, soil, or undissolved organic matter in the source water.”    By the way, I mentioned the article could
be accessed through the Aqua Mira website not because I was advertising their
product as you inferred, but because the Spring 2005 edition of
BackpackingLight, where it first appeared, requires a paid subscription to
access it.

 

Maxine  (Dys-feng shui-nal)   

 

 

    Maxine,
a few things jumped out from your post:

 

>Professor Rockwell very kindly reviewed a
lot of literature and provided his readers with a helpful distillation of
information from a number of studies, but his PhD is in physics or engineering,
not microbiology, 

 

Granted, however his findings have been reviewed
by many people with degrees in those specialties...such as myself, I have two,
and I am a medical doctor, and he is widely believed to be credible and
correct.  Although his degrees are not in
the specialty, it is incontestable that he is very trained and experienced in
searching and reading the scientific literature, and writing coherent summaries
of information subject to severe evaluation.

 

His lifetime of climbing in the Sierra on
basically a weekly basis certainly qualifies him as an empirical user of the
Sierra like few others.

 

If you feel that to consider someone's opinion
requires them to have degrees in microbiology, one wonders why one would
consider your opinion, if that is your sole criterion?

 

>There was a time when people could drink
from nearly all mountain streams and lakes in the US and now we can't--because
Giardia is probably way more prevalent than it was decades ago and it has
reached places where it didn't previously exist. 

 

PROBABLY? 
Is this what you consider EVIDENCE? 
You have not cited ONE SINGLE SOURCE! 
Pul-eeze!

 

>These biofilms can plug up water filters
and apparently can start to grow in water filters that are dirty or old.  You can read about that in an article
"Efficacy of Chemical Water Treatment Technologies in the
Backcountry" by going to the website for Aqua Mira drops and linking to it
from there.  

 

I'm sorry, but this reads like an
advertisment.  Note that the issue of
biofilms DOES NOT ADDRESS the purported title of the article, EFFICACY OF
TREATMENT...IN THE BACKCOUNTRY.  First,
it DOES NOT ADDRESS the issue of Giardia, AT ALL.  It does NOT address the issue of TREATMENT,
AT ALL.  It states:

 

Your understanding of biofilms is....
lacking.  They have NOTHING to do with
plugging of water filters.  Although you
state that one can read about it in the article, the article was NOT about
filters, and did not mention them, and did not comment on the issue you mention!

 

This rather bizzare article criticizes typical
water testing (done all over the world) for using artificial systems......then
describes a obscure system that uses a bacteria that is NOT A GI PATHOGEN, but
is chosen specifically because it forms great biofilms!  How about testing backcountry water.....like
the studies that Dr. Rockwell cited, and that the US Forest Service conducts
yearly in the Sierra????????

 

As they say: "We did not address key factors
that are important in the natural environment"

As they also said: "However, recent
scientific thought leaders in this area seem to be downplaying the real
significance of protozoan pathogen risk in backcountry waters (to the dismay of
portable water filter manufacturers)."

 

Finally, the paper was published on the website
of which he is the owner.  He is cited as
a senior partner of Cytergy, which appears to have gone out of business. Hardly
what I'd call being reviewed by peers.

 

 

 

 

 

Maxine
said:   Your friend Professor Rockwell
very kindly reviewed a lot of literature and provided his readers with a
helpful distillation of information from a number of studies, but his PhD is in
physics or engineering, not microbiology, and his article is laced with some
anecdotal information and conclusions that may or may not be correct and could
lead to some unsafe practices among current readers. 

 

Most
of the data was from the 1980's with an update in 1997.  The Sierras water conditions may not be the
same as it was then.  There was a time
when people could drink from nearly all mountain streams and lakes in the US
and now we can't--because Giardia is probably way more prevalent than it was
decades ago and it has reached places where it didn't previously exist. While
it may not thrive under freezing conditions, Giardia continually gets
reintroduced into the high country every year by wildlife, especially deer, as
well as humans, dogs, cattle, and possibly even horses, mules, and llamas. (I
don't know for a fact that horses or llamas can carry Giardia, just surmising
here.)  SInce humans may be asymptomatic
carriers, they bring it with them by defecating, but they can also shed the
cysts when they bathe in lakes and streams and they can carry some on their
shoes.  If animals eat human feces or
toilet paper, or dig up their catholes, they can become colonized too.  Birds landing in high mountain lakes can
carry lots of things from other bodies of water on their feathers, which is how
fish eggs are often transported into the high country lakes.  So the number and variety of organisms in
certain areas are constantly evolving and new diseases keep emerging over the
years--West Nile Virus, Lyme disease, Rocky Mt Spotted fever, funguses that
infect trees, parasites and worms that infect fish, etc.    

 

The
Sierras water sources are also quite different in August than they are in
June.  Water rushing hard and fast from
yesterday's snowmelt will not be carrying many organisms, but the babbling
brooks and sun-warmed lakes of August harbor a different spectrum of
organisms.  The animals have come out of
hibernation or have returned to the high country, the cows that have grazing
rights in the sections between Sonora Pass and Truckee have meandered into the
higher mountain meadows and are defecating all over the trail and in the streams.  The trail gets covered with a fine layer of
horse and mule droppings, and the flies show up, and humans walk through it all
and carry it all into streams they cross. 
They can also carry organisms into their mouths from their hands,
including giardia cysts, from touching their shoes, the dust on their legs,
their hiking pole handles, the nozzles on their water bladders, and from
leaning on the ground or folding their tarps, etc…  The other thing that happens in late summer
is there is more sediment and solids suspended in water and many organisms
coalesce into biofilms and slimes that allow organisms to attach to a solid and
make it harder for chemicals to penetrate and kill them.  These biofilms can plug up water filters and
apparently can start to grow in water filters that are dirty or old.  You can read about that in an article
"Efficacy of Chemical Water Treatment Technologies in the
Backcountry" by going to the website for Aqua Mira drops and linking to it
from there.  The article concludes that Iodine
cannot effectively penetrate biofilms, and regular chlorine is not especially
effective either.  Chlorine dioxide,
which is the active ingredient in Aqua Mira drops and tabs, was the most
effective chemical in their study for penetrating biofilms and killing
organisms and was less negatively-affected by cold temperatures than the other
substances.  Bear in mind that there
could be a commercial bias since Aqua Mira stands to benefit from this info,
but the article first appeared in BackpackingLight Spring 2005 and the authors
do not work for Aqua Mira.  Note that
while they mentioned that filters can get "infected" the study didn't
really include filters or whether pre-filters can trap the biofilm sufficiently.  

 

I
think Mr Rockwell erroneously concluded that what was making everyone sick
repeatedly on his trip in the Himalayas was giardia because he was assured that
the Sherpas handled the food safely. 
Giardia tends to take 1-3 weeks for symptoms to show up and can last for
1-2 weeks, often longer.  I'm not saying
he's wrong because no one was tested, but what he's describing is what is
typically seen with bacterial food-borne illnesses, just like the kind you can
get in any other developing country from eating unpeeled or undercooked fruits
and vegetables or foods chopped on contaminated cutting boards, etc.  I doubt highly that the Sherpas were cleaning
their cutting boards with bleach, or had been rigorously washing their hands
all the time, or that they really understood what "germs" are.  We had the same problem in Tibet where some
members in my group kept getting sick, and they got immediately better after
taking Cipro, which treats certain bacteria but does not treat Giardia.  The problem stopped after I made the Tibetan
guides soak our fruits and vegetables in iodine treated water using drops I had
gotten to clean fruits with in Mexico. 
I'm pretty sure they were just cutting up clean-looking tomatoes and
cucumbers, etc. which they served to us raw. 
Yes, this is an anecdote too, so bear that in mind.  

 

So,
you can read the info from his article and decide to take your chances in the
Sierras and you might do just fine, especially just after snowmelt.  It's your choice.  But if you get sick and ruin your trip, or
someone else's, or if you have to be evacuated, then the consequences are not
negligible.  We know that a lot of PCT
hikers get sick somewhere around the Kern River or after Kennedy Meadows and,
while it may not be from giardia,  it
still matters--and they could have avoided getting sick had they taken
precautions.   His article may also lead
you to conclude that you're more likely to have minimal or no symptoms if you
get Giardia.  I had Giardia many years
ago from drinking from a waterfall in Mexico, before I knew better.  I was quite sick at first, but assumed it was
just "turista" bacterial infection that would clear up like the
others did.  I felt better after 2-3
weeks but still couldn't eat eggs, peanut butter, or anything with fat without
having severe diarrhea.  I was pretty
young then, finally saw a doctor in the US after about a month, giardia was
confirmed with a stool sample, and by that time I had lost 10-15 lbs and
weighed 93 lbs!  My dog got giardia a
month ago from drinking from a stream in British Columbia.  He was so sick, he needed IV fluids in
addition to the antibiotics.  Obviously,
my own anecdotal experiences affect my own judgement and what I do.  

 

Respectfully
submitted,  

 

Dys-feng shui-nal