giardia - what is the primary source, IN THE WILDERNESS - human or animal?

Question

A coworker and I debated my question. His argument was that there has been a recent surge in giardia cases (in the last 20 years or so) because the number of hikers and such as increased a lot in that time and THEY have spread the organism around in the wilderness. I posited that it can be spread by human feces, but that it is far more likely that people are contracting it from animal sources than from human sources. What do you think? Also, do you know of an authoritative place I can go to for more information along these lines?

Answer 1

Giardia lamblia are excreted in the feces of infected animals, including humans, and can cause diarrheal disease if ingested. They are of particular concern in water treatment. Unlike endospores, they are readily destroyed by boiling. I'm a microbiologist who has seen these little protozoans under the scope, both in cyst and trophozoite form. I was hiking in New Mexican mountains a year ago in a spot where a member of my team had contracted this giardiasis. We were camped near a running stream and knew not to drink from it. The woman who got sick was showering (using a solar shower with water taken from the stream) and evidently wasn't careful about the water around her mouth and must have ingested the cysts which led to her violent cramps and sickness. It was later confirmed in both her diarrhetic and formed stool that she did have dysentery caused by Giardia lamblia.

As far as the primary source? It is mainly animals other than humans. But it isn't just a "hike in the woods" kind of thing...it's any fecal contaminated water supply - not just streams or rivers out in the wilderness. It's a constant problem in third world countries. But if I would have to say specifically which one IN the wilderness...I'd have to side with animals other than humans. There are far more of them in the wilderness than there are humans.

If you heard (that there was a recent surge in giardia cases) from news media....well lets just say that they'll put anything they hear on the air. Remember the supposed "summer of the shark" and how shark attacks were on the rise? In all actuality, the number of attacks was still average - no spike.

If you need a definitive source on this subject, I would check out scientific journals on the web. At least they are supposed to be more of a sure thing on accuracy than personal websites.

Answer 2

More hikers has nothing to do with the presence of giardia. Giardia comes from infected feces. Most hikers are healthy and dont have giardia unless they are drinking water that is infected with giardia so it is common sense that humans in developed countries contribute almost zero percent to giardia in the wilderness. In developing (third world) this is a different story but still isnt gonna be a problem from hikers rather from raw sewage being discharged into water systems without being treated first which would also contribute to hepetitis A

Answer 3

Giardia is caused by a protist, Giardia lamblia; if you drink contaminated water (has human feces containing the protist in its cyst form) you will likely contract teh disease. Boiling water kills the cysts- a good precaution. As far as it increasing, more people than ever hiking and not following basic trail rules and more likelihood that sewage treatment plant may overflow and enter bodies of water.

Answer 4

Animal of course. Very few people who are hikers are stupid enough to defecate in streams, lakes, or rivers. Furthermore, the 'poop' distribution is much higher for animal carriers. I could not find the source. My uncle is a hydrologist, and we discussed this a few years ago. There was a study of the spread of giardia in the west, and he commented something like: "Fifteen years ago, you could drink this water..." But I think that perception may be incorrect. Read the article linked below. You may change your view of what constitutes 'source' and 'spread' in regards to this topic. Hope this helps.

Answer 5

Guarrdia is actually no more prominant now than it was say twenty years ago in fact its numbers are on the down-swing. However you do see sporradic outbrakes in cities due to a failure in there water treatment facility or flooding. You will also see sporradic outbreaks in public swimming facilities when the water is not properly treated.