An article I wrote for the ALDHA-West Gazette, while I was a board member. I appears in the Fall 2019 Gazette
Your alcohol-based sanitizer does nothing to kill Giardia!
“Does this shock you? I know it did me when I first heard this. Doesn’t everyone have hand sanitizer in their poop bag? As you are about to dive into a friend’s trail mix bag, don’t you hear, “did you sanitize your hands” (what you should be hearing is STOP, but we will discuss that another time!)1 After filtering water from a particularly stagnate beaver pond or cow pie water trough, isn’t the first thing you do after collecting water, sanitize your hands?
“In fact, alcohol-based hand sanitizers, the way they are used, have virtually no effect on giardia. So, what does, and what is the best way to protect yourself from giardia in the backcountry? In order to understand how to best prevent Giardiasis while hiking let’s first look at what makes giardia so tough.
“Giardia outside the body is a tough “bug.” Outside the body it creates a Cyst. Literally a hard “cocoon” that allows it to survive for weeks to months outside a host. **
“Once ingested by a host the trophozoite emerges and starts to feed and multiply. The only plus side is that only about one third of those infected actually get sick. Now that we know what it is and how it works, how do we stop it? The best defense is a good hygiene offense. Since most hikers don’t eat many (not enough) fresh foods in the backcountry, the food tends to be packaged or repackaged in some manner so contamination this way is small. The biggest culprit for transmitting germs is our hands, but this is where our alcohol-based hand sanitizer should solve this problem, right?
“Alcohol sanitizers work by actually killing the germs they come into contact with. The alcohol breaks down cell walls and destroys the organisms it comes in contact with. This includes any healthy bacteria that is commonly found on your skin. This however is not a problem for a normally healthy adult as you will readily make more. It will also dry out the skin as it evaporates moisture from the surface and can lead to chafing and cracking if used frequently.
“These types of sanitizers were designed for developing countries, without clean water sources, (which could be most backcountry hiking settings) and have been in use in hospital settings for years and have been found to be very effective against most germs. However, alcohol sanitizers are ineffective if your hands are soiled, meaning debris like blood, grease, chemical solvents and especially dirt. How ironic then, that in order to “clean” your hands, your hands have to be clean. Alcohol sanitizers will evaporate if not contained but it is this evaporation that helps break down and carry away dead germs. In order to be effective however alcohol-based hand sanitizers must be wet on the skin for between 30 seconds and 5 minutes (how many of us do that?).
“It used to be commonly believed that Giardia could be killed by alcohol-based methods if it was 80% or stronger with either Isopropyl or Ethanol alcohol. The problem here is none of your consumer-based hand sanitizers come at this strength. * They range from 47% to about 70% and the same brand can vary widely, which may account for the wide range of pricing as the same brand can have different concentrations of alcohol.
“Spoiler alert- There is a study that shows that alcohol-based hand sanitizers do kill Giardia by breaking down the cyst with as little as 63% alcohol and found no difference between the 63% concentration and the 80% concentration with the caveat that it had to be left on the hands for 5 minutes! 5 Something I am sure none of are doing.
“Good old soap and water. Surprise! Soap and water don’t actually kill germs. The combination of the soap as a lubricant to loosen and lift debris and germs, including Giardia cysts, from your skin and the water to wash it all way is the most effective way to prevent disease. Plain old soap and water are actually more effective than antibacterial soaps, as the concentration of the antibacterial agent is not enough to kill bacteria but used to linger on the skin to help prolong “clean hands.” It is these antibacterial agents that have gotten the reputation as being the cause for breading “super germs” resistant to normal antibiotics. Plain soap and water made into a good lather and used for the time it takes to sing Happy Birthday to yourself eliminates 90% of all bacteria and viruses from your hands. Want to eliminate 99%? Sing Happy Birthday to yourself twice and it doesn’t matter if the water is hot or cold, although really hot water can blister and scald your hands and actually hinders the amount of time you want to wash them, so stick with lukewarm to cold water. Don’t forget to dry your hands as well. The whole hand washing scenario should take about a minute to insure truly clean hands.
“Summary: The most effective way to keep your hands clean and therefore keep clear of the biggest cause of getting sick on the trail is to wash our hands with soap and water for about 40 seconds and then thoroughly dry them. If you are in a situation where water is scarce an alcohol-based hand-sanitizer of 63% alcohol will kill many germs but will not be effective against Giardia unless left on the hands for 5 minutes. So, think about replacing or at least augmenting your hand sanitizer with a dropper bottle of regular soap!
Citations and Notes:
1. STOP- the single biggest cause of hikers getting sick is sharing food with others. You may love your friends but assume they are carriers of disease. If you are going to share your trail mix or any food, have them hold out their hands and pour them some or hand them some, don’t allow anyone to stick their hands in your food bag or touch your food.
2. https://blog.gotopac.com/2017/05/15/why-is-70-isopropyl-alcohol-ipa-a-better-disinfectant-than-99-isopropanol-and-what-is-ipa-used-for/
3.Antimicrob Agents Chemother. 2015 Nov; 59(11): 6749–6754. Published online 2015 Oct 13
4. What Organisms Does Isopropyl Alcohol Kill? by Tucker Cummings
(5)“*Author comment What about Bleach? Bleach does penetrate the Giardia cyst and kill the trophozoites, but unlike alcohol-based sanitizers, where the alcohol evaporates and is not absorbed through the skin, bleach is absorbed through the skin and can cause other health risks, so it is not recommended for human consumption.
6.Harvard EDU newsletter January 2007
** author comment If you think it would be nice to cool off in a still pond along the trail, think twice, especially one with signs of animal use like beavers and cattle. Any open sores or cuts, including blisters on your feet and especially an accidental mouth full of water are an invitation to Giardiasis.
