Viruses are the smallest infectious agent known to men. Like they say size does not matter, as small is it may be, diseases from viruses can be extremely devastating. The first virus was discovered in 1892, tobacco mosaic virus. By 1898 Martinus Beijerinck documented the discovery of 5000 types of virus. Now there are million types of virus known to man.
Viruses unlike men do not discriminate. They can be found in plants, animals and men. Viruses can spread in different ways. The transmission from mom to child is termed as a vertical transmission, for example HIV or Hepatitis B. However most transmission is horizontal, whereby it is spread person to person. Horizontal transmission may not necessary mean direct contact. Sometimes there is a need for a vector to pass on the disease. One example is of course dengue, and the vector is a the Aedes mosquitoes. Some viral diseases are caused by body fluid either through sexual contact, or exposure to infected blood, ie HIV, hepatitis B and C. Then of course direct contact or by oral route is one of the most common and easiest way for the disease to spread.
Many viral infections like the common cold is self limiting. Most times viral infections provoke our immune system to eliminate the virus. Our knowledge of this immune response has enable us to develop many vaccinations over the years.
Viruses and viral infections has much impacted social history. One of the oldest viral infection known to men is the smallpox. The smallpox was carried by the European when they explored America. The indigenous Americans had no natural resistance to the disease, a disease that were never known to them. Smallpox killed probably about 70% of native Americans, after the arrival of Christopher Columbus, the very cause of the fall of ancient civilisation like the Incas and Aztecs. Smallpox was not only deadly, with more than a 60% mortality rate but it was highly contagious. Thanks to the advent of vaccination by Edward Jenner, smallpox has been eradicated, and on the 8th of May 1980, WHO announced the world is free of smallpox, the vaccination programme for smallpox was no longer necessary.
Of course since the discovery of small pox vaccine we have now new viral diseases to deal with, many pandemics, epidemics and outbreaks have occurred and will continue to change our social dynamics and history. We must realise vaccination can make a difference to the disease process and the eradication of certain diseases and we must play our part in this eradication programme.
Dr Betty Teh
Founder and Editor in Chief
Beating Hearts
