Small Pox: The only human infectious disease that has been eradicated

Team Udayavani, Jul 14, 2020, 2:04 PM IST

Small Pox was a serious infectious disease caused by the variola virus. It was contagious which means, it spread from one person to another. People who had smallpox had a fever and a distinctive, progressive skin rash

Smallpox was responsible for millions of deaths in the past as there was no treatment and once you caught smallpox nothing could be done but let the infection run its course.

It is thought to have killed more than 300 million people and was fatal to around 30% of those who became infected.

Small pox leads to rash which develops into clusters of fluid-filled pustules. It can look superficially similar to the chickenpox rash, although the two diseases are caused by different viruses.

Early symptoms include high fever and fatigue. The spots on the skin become filled with clear fluid and later, pus, and then form a crust, which eventually dries up and falls off.

Similar to Coronavirus, the virus spreads in droplets and can be expelled into the air via coughing and sneezing. It can also be passed on via the fluid from smallpox blisters

The incubation period for smallpox is generally 12 to 14 days, which means a person may not show signs of infection for around two weeks

One of the first methods for controlling the spread of smallpox was the use of variolation. Variolation is the process by which material from smallpox sores (pustules) was given to people who had never had smallpox. This was done either by scratching the material into the arm or inhaling it through the nose

The first smallpox immunization was created by Edward Jenner in 1796. But it took more than 200 years and a worldwide vaccination program to eradicate the disease.

The first experiment to test this theory involved milkmaid Sarah Nelmes and James Phipps, the 9 year-old son of Edward Jenner’s gardener. Dr. Jenner took material from a cowpox sore on Nelmes’ hand and inoculated it into Phipps’ arm. After several months, Jenner exposed Phipps a number of times to variola virus, but Phipps never developed smallpox.

After several years, vaccination became widely accepted and gradually replaced the practice of variolation. The smallpox vaccine could prevent infection up to four days after initial exposure. The vaccine itself does not contain any of the variola virus but a related one called vaccinia.

However, mild reactions to the vaccine can include fever, fatigue and tiredness. But it also carries a small risk of serious side-effects

For this reason, contact tracing and selective vaccination have been key in the eradication of smallpox.

The last known naturally occurring case of smallpox was diagnosed on Oct. 26, 1977, in Merka, Somalia. The World Health Organization (WHO) declared smallpox eradicated in 1980.