In times where there is rampant spread of diseases, such as in pandemics, epidemics or outbreaks, good hand hygiene can come a long way in preventing the spread. It is a cost-effective public health measure which most people can perform when instructed properly. It is effective in breaking the chain of infection of a wide range of transmissible diseases and it is one of the safest preventive methods. However, a lot of people may not be aware that the quality of the water that is used for handwashing plays a significant role with regards to the efficacy of this preventive measure. Now that a lot of countries are advocating frequent handwashing for the prevention of diseases, it is equally important to inform the public about the importance of the quality of handwashing water.
Microbial pathogens can spread from person to person through touch. Someone whose hands are contaminated and would touch surfaces or objects can contaminate that surface or object as well. When someone else would touch these, they are now at risk of infection. By simply washing one’s hand, infection in these scenarios would be averted. When soap and water is not readily accessible and you need to clean your hands. A hand sanitizer containing a minimum of 60% ethyl alcohol would suffice. However, hand washing with soap and water is still the preferable way of decontaminating one’s hands.
But how do you wash hands properly? According to the CDC it only takes five steps:
Wet hands with clean running water.
Apply soap and lather. Rub hands together. Lather the back of the hands, between fingers, and under the nails.
Scrub the hands for at least 20 seconds. You can sing the happy birthday song twice if you find it difficult to time yourself for 20 seconds.
Rinse your hands properly. Make sure all of the soap is removed.
Dry your hands with a clean towel.
Now the problem comes with the determining what CDC means by ‘clean running water’. What is the criteria for ‘clean’ hand washing water? The CDC or any other health institution or agency currently does not possess any guidelines concerning the quality of hand washing water. A 2019 study supplemented this deficiency in the guidelines by conducting experiments on acceptable hand washing water quality. Through their research they found that hand washing water containing less than 1000 E. coli colony-forming units per 100 mL could still remove E. coli from the hands with a probability of 99.9%. According to their tests, handwashing with non-potable water could still reduce contamination of the hands. So for now, the acceptable hand washing water quality is one that contains less than 1000 E. coli colony-forming units per 100 mL.
Rubbing alcohol - an alternative for Hand Disinfection
As mentioned earlier, if you don’t have access to soap and water and you really need to disinfect your hands. Using a hand sanitizer with an alcohol concentration of 60% or more is an acceptable alternative.
Should the alcohol concentration be 70%?
Tests have been conducted regarding the efficacy of alcohol of various concentrations. 60% to 90% Isopropyl alcohol was demonstrated to be rapidly antimicrobial against bacteria, fungi, and viruses. Going lower than 60% significantly decreases the efficacy of alcohol. Going beyond 90% also reduces their bactericidal, virucidal, and fungicidal properties.
But what is the most effective alcohol to water ratio?
The amount of water present in the alcohol solution is an important factor when it comes to its ability to destroy or inhibit the growth of pathogenic microorganisms. Water allows the alcohol to penetrate the cell wall more completely. Isopropyl alcohol solutions containing 70% alcohol and 30% water can permeate the entire cell. Once this solution has entered the entire cell, all of the pathogenic microorganisms’ proteins would coagulate and the microorganism dies. The extra water also aids in keeping the alcohol in liquid form. When the alcohol remains in liquid form for a longer time, their contact time with the pathogens would be lengthened which ultimately improves efficacy. Increasing the alcohol concentration beyond 90% coagulates the pathogen’s proteins instantly which prevents the infiltration of the alcohol solution. To answer the question, the most effective alcohol concentration is 70% but alcohol solutions of 60% to 80% are sufficient.
Is 40% ethyl alcohol enough?
As mentioned previously, rubbing alcohol with a concentration of less than 60% are significantly less effective than those with a concentration between 60% to 80%. Another laboratory study investigated the antimicrobial properties of 40% alcohol and found that they are significantly weaker. The lower you go the more ineffective the alcohol becomes and at 10% the alcohol had almost zero effect on microorganisms.
When to wash your hands
It is important to know when to wash your hands. If you wash your hands infrequently then you increase your risk of infection. However, this doesn’t mean that washing your hands too often is beneficial. Washing one’s hands with soap and water removes both transient potentially pathogenic microorganisms and normal skin flora. Aside from this, some of the upper layers of the skin are shed off, drying occurs, and the pH of the skin increases. All of these conditions may weaken the normal flora of the skin and encourage the subsequent colonization by transient microorganisms. Some studies have even demonstrated an increase in microbial population in the hands of an individual who washes their hands too often. So to prevent these from happening, we need to know when it would be necessary to wash one’s hands.
Always wash your hands before:
Preparing food or eating - Handling food with contaminated hands is one of the most efficient ways of transferring a gastrointestinal pathogen from one person to another. Eating without washing hands could lead to auto-infection or infecting one’s self with whatever pathogen the individual is carrying. To prevent all of these problems, you need to wash your hands before preparing food or before eating.
Treating wounds or caring for a sick person - Wounds are open breaks in the skin. Treating an open break in the skin with contaminated hands may lead to an infection. A sick person is vulnerable to infections as well. Health workers are required to wash their hands when treating their patients. This is applicable in the home setting as well.
Inserting or removing contact lenses - the eyes are considered to be a ‘privileged area’. This means that the eyes are not subject to the strict surveillance of our immune system. With that said, the eyes must be protected from contamination because the defenses in this area are weak.
Always wash your hands after:
Preparing food - Especially when handling raw ingredients. Their surfaces may contain microorganisms that may be pathogenic. Aside from that, food particles that remain in your hands as a consequence of not washing them may encourage microorganisms to grow.
Using the toilet, changing a diaper, or cleaning up a child who has used the toilet - All of these activities could contaminate the hands with fecal matter. Hands that are contaminated with fecal matter may spread feco-oral diseases. Washing one’s hands after doing these activities prevents this from happening.
Touching an animal, animal feed or animal waste - animals are not as hygienic as humans. Interacting with them as mentioned may lead to the soiling of one’s hands. To prevent infection, hand washing is highly recommended.
Blowing your nose, coughing, or sneezing - These acts will definitely contaminate your hands. When you blow your nose, cough, or sneeze on to your hand or hands, you should avoid touching a person or an object with that hand or hands. If possible, wash your hands immediately. If that is not possible, use a hand sanitizer in the least.
Treating wounds or caring for a sick person - open wounds aren’t exactly sterile all the time, treating them may contaminate your hands. Touching a sick person may also transmit some of their pathogens on to your hands. To avoid spreading disease to others, you must wash your hands after treating wounds or caring for a sick person.
Handling garbage - touching something as dirty as garbage may contaminate your hands. Make sure to wash them after handling garbage.
Handling pet food or pet treats - Pet food or pet treats are not prepared as hygienically as human food. Handling them would likely contaminate one’s hands. Washing one’s hands after handling them is advised.
How effective is hand washing?
Before we discuss the efficacy of hand washing, we must try to understand COVID-19’s chain of infection. This is a virus that is spread through droplets. Meaning the virus is shed from the infected person’s respiratory tract to their surroundings through their respiratory secretions. This respiratory secretion could travel from one person to another through coughing or sneezing. However, if a person coughs or sneezes onto their hands and then touches another person, it can be transmitted through this way as well. When a person whose hands are contaminated with the virus touches an object, that object may harbor the virus as well. When someone else touches that object, they may acquire an infection with the virus. This third scenario can be prevented if proper hand washing is observed. As mentioned earlier, even if the water that is used for hand washing is not potable, it is still effective at removing bacteria. This is true for COVID-19 as well.
So far, studies regarding the current pandemic has shown that hand hygiene is essential for protecting the lives of health care workers. But it doesn’t stop there, for there are also studies that have shown that hand hygiene is highly beneficial for the general public as well.
Handwashing Water Quality
The efficacy of hand hygiene is based upon its ability to remove pathogens from the hands. When done correctly, hand hygiene has been shown to remove 99% of microorganisms from the hands. With this in mind, it is logical to assume that washing your hands with contaminated water is counter productive. However, tests have shown that using non potable water, as long as it is not heavily contaminated, to wash hands is still significantly effective at keeping contamination low.
Not all tap water is potable. This is especially true in third world countries. Reviews and meta-analyses have shown that households in low- and middle-income countries have tap waters which contain about 1000 colony forming units of E. coli per 100mL on average. If this is so, even in low- and middle-income countries, hand washing using their tap is still effective at combating COVID-19 without having to worry about other water borne diseases. For households whose tap water is not fit for handwashing. In other words, the tap water contains >1000 colony forming units of E. coli. Handwashing is still effective against COVID-19. However, this is not ideal because the hands would be contaminated with whatever is in the water. This water may contain microorganisms responsible for water borne diseases. The person who washes their hands with this kind of water is protected from COVID-19 but they become susceptible to water borne diseases.