Best Giardia Story Ever

January 6, 2011

A buddy of mine who works as a college outdoor education instructor recently shared an experience with me. For reasons I will mention later, today is an amazingly appropriate day to bring this up.

My friend related a visit to one of the college’s treks by a student instructor from the west. The visitor was appalled to learn that this particular program did not practice universal water treatment during their expeditions. When told that the local instructors had carefully considered things and no longer recommended routine treatment of most Adirondack waters, he commented that it must be because of something unique to New York, since tasting even a drop of untreated water in the American west was “guaranteed” to result in giardiasis. He went on with a litany of reasons why this was to be avoided at all costs, not the least being that giardiasis was essentially incurable, and that those unfortunate enough to acquire it would have it forever–often flaring up any time an offending food was consumed. He treated everything he drank on the trek. No one else did. Everyone was just fine.

Of course, everything about this would be simply silly if it were not for the fact that the person involved is en route to becoming a professional outdoor educator, presumably about to share such nonsense with unsuspecting students. This is hardly a “controversy” anymore; it is difficult to identify any true expert in this field who considers the “treat everything” approach to be necessary or appropriate. Which brings me to the reason why today is a very good time to tell this tale.

A report today ( has confirmed once and for all that the original study linking vaccines to autism was not only incorrect, it was fraudulent. The 1998 study, by a British quack named Andrew Wakefield, reported 12 reportedly normal children in whom autism developed as a consequence of the MMR vaccine. The journal in which it was published retracted it long ago because of concerns about its validity, and all of Wakefield’s coauthors disassociated themselves with its conclusions. Literally scores of well-designed studies involving thousands of children have been published subsequently, none of which have supported the Wakefield hypothesis. One would think that the concern would have gone away by now.

Sadly, things didn’t work out that way. In the nearly 13 years since the Wakefield publication, concern about the MMR vaccine became rampant, leading many families to avoid it. This, in turn, has resulted in a resurgence of measles in the world, with countless preventable deaths. Nonetheless, uninformed “experts” have continued to trump this bogus association, believing a study of 12 patients over well-designed trials with thousands.

Believe it or not, this situation is nearly identical to the current infatuation of some wilderness folks with water-borne giardiasis.

There has been exactly one peer-reviewed scientific study suggesting a link between wilderness water consumption and giardiasis. This report, from 1976, reported that about 2/3 of participants in a camping trip in Utah’s Uinta mountains acquired giardiasis. The authors ascribed the outbreak to consumption of surface water.

In subsequent years, it has become clear this this report was incorrect (although certainly not fraudulent–just wrong). Analyzing this incident in light of contemporary knowledge about giardiasis has made it clear that this was an epidemic of food- or hand-to-mouth borne infection. (This is discussed in more detail in a paper available on my website – Evidence-Based Medicine in the Wilderness: The Safety of Backcountry Water).

Although no subsequent scientific studies have shown any association between North American wilderness water consumption and giardiasis (or, indeed, any infection), the damage was done with the single 1976 paper, just as it was with Wakefield’s 1998 autism/vaccine study. “True believers” such as the student instructor continue to tout misinformation which has been long-since discredited–often embellishing it along the way.

While the damage done by this over 30 year old paper pales in comparison to that of the Wakefield study (I doubt that anyone has died because of it!), it certainly has had negative effects. Most strikingly, the incessant attention to water quality in the backcountry has eclipsed attention to a much more important strategy–hand washing—which probably would have prevented the Utah outbreak! It has created the market for a dizzying array of technologic fixes (filters, “steri-pens”, etc) which exist to solve a problem which doesn’t exist. It has perpetuated very bad science among folks who aspire to professional careers in outdoor education.

I’ll conclude with a “stay tuned”. With a couple of colleagues and a student, I am analyzing data from a series of studies we have done examining the colonization of backpackers’ hands with (hope you’re not eating lunch now) organisms found in FECES. Without giving away the results, let me just suggest that you avoid shaking hands with folks you meet in the wilderness…