Topic

Do you filter?


Forum Posting

A Membership is required to post in the forums. Login or become a member to post in the member forums!

  • This topic is empty.
Viewing 16 posts - 51 through 66 (of 66 total)
  • Author
    Posts
  • #1539181
    backpackerchick
    BPL Member

    @backpackerchick

    Amoebic dystentery a different story. Can cause serious and ongoing problems in a foreigner. If you're going to these places, boil for the full five mins. Forget the potions and fancy gadgets.

    #1539234
    Laurie Ann March
    Member

    @laurie_ann

    Locale: Ontario, Canada

    "The most frequent method of infection is by drinking contaminated water."

    http://bodyandhealth.canada.com/condition_info_details.asp?disease_id=309

    #1539235
    Laurie Ann March
    Member

    @laurie_ann

    Locale: Ontario, Canada
    #1539237
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    The full quote from the Canadian media company (NOT the Canadian government) is:

    " The most frequent method of infection is by drinking contaminated water. However, people may also become infected through hand-to-mouth transmission. This involves eating contaminated food or touching contaminated surfaces and unknowingly swallowing the parasite."

    Unfortunately they give NO references to support their statement. While both paths are of course known to be involved, their statement has to be treated as pure journalese. We need better than this.

    Cheers

    #1539241
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Health Canada (a Government site) say:

    " Have these parasites been found in Canadian drinking water supplies?
    Low levels of both parasites, especially Giardia, were detected in a national survey of drinking water conducted by Health Canada. Only a small fraction of the parasites appeared to be viable and their ability to infect humans was not determined."
    Makes you wonder whether the water path really is all that significant, doesn't it? Low level, mostly not viable …

    " Nevertheless, outbreaks of illness linked to these parasites in drinking water have been reported in several provinces."
    I guess that it is easier to blame the water supply rather than poor personal hygiene.

    "Their spread in swimming pools has also been reported."
    A curious one. At first blush you could understand this, what with little kids swimming around, but then you start to wonder. Most swimming pools are laced with some sort of chlorine treatment, at a level where the smell and taste are readily discernable. But this same chlorine treatment is supposed to make the water safe for us to drink when we treat our drinking water in the back country? Does this add up?

    Cheers

    #1539310
    Aaron Sorensen
    BPL Member

    @awsorensen

    Locale: South of Forester Pass

    I'm not talking about the most frequent method of infection. I'm talking about it spreading from person to person.

    #1539331
    j lan
    Member

    @justaddfuel

    Locale: MN

    Thank you for bringing amoebiasis to light, I had this in Guatemala and ended up curing it using a strong wormwood (ajenjo) tea.

    Also in the discussion of hand washing, can i use diluted/full strength stove fuel to sanitize? (no white gas, ha!)

    #1539336
    Anonymous
    Inactive

    "I guess that it is easier to blame the water supply rather than poor personal hygiene."

    Roger,

    Both you and Hartley have stated unequivocally, or 99% unequivocally, in previous posts that giardia transmission is fecal-oral if I understand your posts correctly. However, neither of you have offered any documentation to support your claim. The Canadian Government, by your own reference, has pointed to waterborne giardia outbreaks of giardosis. Surely they have some credibility? If not, why not? What are your countervailing sources? I did a cursory search with the key words "giardia transmission" which came up with an extensive list, as might be expected. The first 2 I clicked on mention waterborne transmission as one of the primary vectors. Neither of these sites appear to be flogging any related product, so I tend to give them some credibility. They are:

    http://diarrhea.emedtv.com/giardia/giardia- transmission.html

    http://www.giardosis.org/transmission.aspx

    Lots of others out there, but I figure this will get us started on the path to a more nuanced view of how giardia is transmitted.

    Cheers

    #1539345
    Chris Townsend
    BPL Member

    @christownsend

    Locale: Cairngorms National Park

    Here's a meta-analytic study:

    http://www.ncbi.nlm.nih.gov/pubmed/10737847

    Conclusion: "the evidence for an association between drinking backcountry water and acquiring giardiasis is minimal."

    #1539349
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Tom

    > What are your countervailing sources?
    A fair question! Please remember that my literature research in this area was done some years ago, so I have to refresh my memory. The NCBI web site (free registration) is an invaluable resource here.

    OK, try this for size:

    Epidemiol Infect. 1994 Aug;113(1):95-102
    Risk factors for giardiasis: a case-control study in Avon and Somerset.
    Gray SF, Gunnell DJ, Peters TJ.
    Research and Development Directorate, South Western Regional Health Authority, Bristol.

    Giardia lamblia is a common and increasing cause of gastrointestinal illness in the UK. We report a case-control study that examined risk factors for giardiasis. Patients with giardiasis were identified from reports to the Consultants in Communicable Disease in Avon and Somerset, and age-sex matched controls were obtained from their general practitioners' lists. Details of travel history, water consumption and recreational water use were collected by postal questionnaire. Over the period July 1992 to May 1993, 74 cases and 108 matched controls were obtained. The data were analysed using conditional logistic regression. Swimming appeared to be an independent risk factor for giardiasis (odds ratio 2.4, 95% CI 1.0 to 6.1, P = 0.050). Travel (P = 0.001), particularly to developing countries, and type of travel (P = 0.004)–that is, camping, caravanning or staying in holiday chalets–were also observed to be significant risk factors. Other recreational water use and drinking potentially contaminated water were found to be not statistically significant after adjustment for other factors.

    PMID: 8062884 [PubMed – indexed for MEDLINE]

    Cheers

    #1539404
    Anonymous
    Inactive

    "Here's a meta-analytic study:"

    Many thanks, Chris. This study plus an article by Robert L.
    Rockwell concerning giardia in the Sierra Nevada have pretty much nailed things down as far as I'm concerned. The case for fecal-oral contamination is pretty convincing, albeit indirect. I will henceforth proceed with that in mind and lighten my load in the process(no more filter in most areas I frequent).

    #1539407
    Anonymous
    Inactive

    "OK, try this for size:"

    Hi Roger,

    Initially I didn't find this study convincing due to the small sample size, but it compelled me to dig a little deeper and I didn't get much further than an article by Robert L. Rockwell, "Giardia Lamblia and Giardiasis with Particular Attention to the Sierra Nevada". It made a very convincing case based on dozens of water samples taken by Forest Service biologists throughout the Sierra. Nowhere did they find giardia present in concentrations anywhere near high enough to infect a human. The inference is that most cases that do occur must be via another path, i.e. fecal-oral transmission, allowing for the possibility of locally high concentrations occasionally being ingested by an unlucky backpacker. Sampling is a tricky business when trying to make inferences about large areas(think soil testing), but it's the best tool available. Then I read Chris's post and went to the meta study he mentioned. All data point to the same conclusion, and I am convinced that you guys have it right. I am especially happy that I now have the last bit of information I need to ditch my filter, since I backpack primarily in the Sierra. Thanks to one and all for a very informative discussion.

    Cheers

    #1539461
    Laurie Ann March
    Member

    @laurie_ann

    Locale: Ontario, Canada

    I have to disagree with the people that say waterborne is virtually impossible and that it's just an excuse for poor hygiene.

    Maybe it's a regional thing but I've been in situations where I am camped water that is creek fed. Anyone who's travelled by canoe or pack in Canada's boreal knows the risks of waterborne illness especially when the creek you've just travelled down required crossing 10 or so beaver dams. They don't call it "beaver fever" for nothing. Sure on bigger bodies of water and spring fed sources the chances are nominal but on small northern lakes and streams you are taking a risk everytime you drink something unfiltered/untreated.

    #1539559
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Laurie

    I don't think any of the researchers said that 'waterborne is virtually impossible'. Neither did I say that. On the other hand, I will say that many cases of gastro in the wild are due to poor personal hygiene.

    The phrase used in one case re Giardia was 'Other recreational water use and drinking potentially contaminated water were found to be not statistically significant after adjustment for other factors.' What that means is that other causes were far bigger.

    I think we are looking at the difference between scientific research with real data collected in the field and anecdotal worries. There's room for both. In fact, I know of one area here in Oz where I would be very careful myself.

    So just because various research groups have found the hazard to be statistically insignificant in many areas does not mean that you have to change what you do. Far from it in fact. If you are concerned in the boreal region, take precautions.

    Cheers

    #1544584
    Larry De La Briandais
    BPL Member

    @hitech

    Locale: SF Bay Area

    I use to never filter or treat the water at the place I go to in the Sierras. But, I am/was probably immune to giardia. I'm fairly sure I drank giardia infected water every summer as a kid (cattle in the creek that the water came from, untreated). Never bothered me.

    Never filtered or treated the water at the backpacking spot I go to for the longest time. Started filtering with a First Need (over kill I know) some time in the late 80s, mostly for taste. I bought the First Need as that's what my buddy had and I found it on clearance sale at REI. I've since added the MSR prefilter, which is the best one I've found.

    Since then I was diagnosed with giardia (via "samples") and was treated after arguing with the doctor. My position is that I had to have been infected for at least 20 years without symptoms. His was that it was the only thing that came back positive. Since I was already getting better, I considered not taking the medication. However, I need to get back to work as soon as possible, so I took it.

    #1545211
    Denis Hazlewood
    BPL Member

    @redleader

    Locale: Northern California

    Don't ever let anyone put their hand into your trail-mix bag.

Viewing 16 posts - 51 through 66 (of 66 total)
  • You must be logged in to reply to this topic.
Forum Posting

A Membership is required to post in the forums. Login or become a member to post in the member forums!

Get the Newsletter

Get our free Handbook and Receive our weekly newsletter to see what's new at Backpacking Light!

Gear Research & Discovery Tools


Loading...