science-behind-soap-and-sanitiser-use-in-tackling-covid-19

Context:Guidelines by the World Health Organization specify that one of the ways to reduce the risk of infection is by regularly and thoroughly cleaning one’s hands with an alcohol-based hand rub or washing them with soap and water. 

  • Regular washing is considered important as the virus tends to be present on different surfaces that are regularly touched with hands.

Washing with soap to help get rid of the coronavirus

  • The dirt ingrained on our hands contains innumerable viruses and bacteria. 
  • Working mechanism of soap molecules:
    • Soap molecules are pin-shaped with a head that is water-loving (hydrophilic) and a tail that is oil-loving (oleophilic). 
    • Being oleophilic, the tail portion of the molecule tends to have an affinity for and ‘competes’ with the lipids in the virus envelope. 
    • Since the chemical bonds holding the virus together are not very strong, the long oleophilic tail gets inserted into the envelope and tends to have a ‘crowbar’ effect that breaks the lipid envelope of the virus. 
    • The tail also competes with the bond that binds the RNA and the lipid envelope thus dissolving the virus into its components which are then removed by water.
  • Effectiveness of soap compared to plain water:
    • Washing with water without using soap helps reduce the amount of microbes but does not remove most of the virus and bacteria completely. 
    • Therefore Using soap is far more effective in removing microbes.
  • Other details:
    • Importance of oil loving tail of soap:The oil-loving tail of the soap molecule also disrupts the bond that binds dirt and non-enveloped viruses to the hand. 
    • The dirt and viruses are surrounded by several tails making them remain as suspended particles. 
    • Rinsing with water washes away the suspended particles leading to clean hands.

Alcohol-based hand sanitisers help get rid of coronavirus

  • Working mechanism:
    • On similar principles of working of soap, the alcohol present in hand sanitisers dissolve the lipid envelop, thus inactivating the virus. 
    • Also the alcohol also tends to change the shape or denature the mushroom-shaped protein structures that stick out of the lipid envelop. 
    • The mushroom-shaped protein structures help the virus to bind to special structures found on human cells and enter the cells. 
  • Effectiveness of sanitisers:
    • For the effectiveness the sanitisers should contain at least 60% alcohol.
    • Need of sufficient amount:Unlike soap lather, the alcohol does not come in contact with all parts of the hand. So care needs to be taken to use sufficient amount of sanitiser to increase the coverage. 
    • Non Removal of dead viruses:Unlike water, alcohol run does not remove the dead viruses from the hand. 
    • While a sanitiser can quickly reduce the number of microbes, it does not get rid of all types of germs, and is not as effective when hands are visibly dirty or greasy.

 

About Pathogens

  • A wide range of organisms belonging to bacteria, viruses, fungi,protozoans, helminths, etc., could cause diseases in man. Such disease causing organisms are called pathogens
  • Most parasites are therefore pathogens as they cause harm to the host by living in (or on) them. 
  • The pathogens can enter our body by various means, multiply and interfere with normal vital activities, resulting in morphological and functional damage. 
  • Pathogens have to adapt to life within the environment of the host.

About Viruses

  • The viruses are non-cellular organisms that are characterised by having an inert crystalline structure outside the living cell.
  • They are not considered truly ‘living’, if we understand living as those organisms that have a cell structure. 
  • In addition to proteins, viruses also contain genetic material that could be either RNA or DNA. 
  • No virus contains both RNA and DNA. A virus is a nucleoprotein and the genetic material is infectious.
  • In general, viruses that infect plants have single stranded RNA and viruses that infect animals have either single or double stranded RNA or double stranded DNA.
  • They are inert outside their specific host cell. Viruses are obligate parasites.

                                      

Source:Wikipedia            

Viruses and the lipid layer

  • Viruses such as coronavirus, influenza-causing viruses, Ebola, Zika have their genetic material encased in a layer of fat called the lipid envelop.
  • The envelopes are typically derived from portions of the host cell membranes (phospholipids and proteins), but include some viral glycoproteins. 
  • They may help viruses avoid the host immune system.  
  • Not present in all viruses:Certain viruses do not have the lipid envelop and are called the non-enveloped viruses.
    • Rotavirus which causes severe diarrhoea, poliovirus, adenovirus that cause pneumonia and even human papillomavirus (HPV) do not contain the lipid envelop.

Source:https://www.thehindu.com/sci-tech/science/how-does-soap-use-help-in-tackling-covid-19/article31070630.ece

Image Source:TH