[pct-l] Giardia Lamblia - Excellent informative article by Robert L. Rockwell, Phd

[Ken Murray]

http://bwca.cc/tripplanning/waterfiltration.htm

"In Long Distance Hiking: Lessons from the Appalachian Trail, Roland Mueser interviewed thru-hikers who spent months walking the entire 2,150-mile-long trail. He asked about their water treatment strategies and illnesses, and found no difference in the rate of illness between those who treated or filtered the water, those who sometimes did and those who didn't filter or use disinfectants.

To test how bacteria spreads in camping situations, Gerba took a group into the Santa Catalina Mountains north of Tucson, Ariz. He split the campers into three subgroups: those who didn't wash their hands, those who washed with soap and water, and those who used alcohol gels. The hands of those who didn't wash were soon covered with E. coli bacteria. Those who used soap and water had some E. coli, and those who used alcohol gels had the cleanest hands."

http://en.wikipedia.org/wiki/Hand_washing#Substances_used

"Alcohol-based hand sanitizers are almost entirely ineffective against norovirus or Norwalk type viruses, the most common cause of contagious gastroenteritis."

"The efficacy of alcohol as a hand disinfectant has been shown to decrease after repeated use, probably due to progressive adverse skin reactions, whereas the efficacy of an alcohol-free hand sanitizer based on Benzalkonium Chloride as its active ingredient has been shown to increase with repeated use"

"n a recent study, the effectiveness of alcohol was shown to decrease after repeated use. The study demonstrated that, unlike Benzalkonium Chloride, alcohol does not have persistent or cumulative antimicrobial activity after application"

"Hand antiseptics and soap and water will not kill the endospores of bacteria (e.g., Clostridium difficile and Anthrax) and the spores of protozoa (e.g., Giardia lamblia) but soap and water may wash them down the drain. When such microorganisms are likely to be encountered, soap and water hand washing followed by use of a good hand antiseptic is preferable"

Best study I see on the issue of alcohol killing spores (clostridium is similar to giardia, both spores:

http://www.ncbi.nlm.nih.gov/pubmed/20429659

"CONCLUSIONS: Hand washing with soap and water is significantly more effective at removing C. difficile spores from the hands of volunteers than are ABHRs. Residual spores are readily transferred by a handshake after use of ABHR."