Every year we see Polio Eradication campaign by Government of India. We see celebrity brand ambassadors like Amitabh Bachchan, Sachin Tendulkar campaigning on TV, Media etc. But what is meant by disease eradication? Do we kill each virus responsible for the disease? When we ascertain that the disease is eradicated? Does it guarantee that there will be no disease infected person in the world? WHO declared eradication of Smallpox. What does that mean?
To understand this, first we need to understand what a vaccine is. Wikipedia says- A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing micro-organism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body’s immune to recognize the agent as foreign, destroy it, and “remember” it, so that the immune system can more easily recognize and destroy any of these micro-organisms that it later encounters. So basically a vaccine is weakened form of the virus which is administered to us and our body can develop immune system to fight it. We make our body prepare to fight the actual virus/microbe when they enter into the body, a kind of preventive measure.
Now let us see that is eradication– There is difference between eradication and elimination. Eradication means reduction of infectious disease in global prevalence to zero and elimination means reduction of infectious disease in regional prevalence to negligible amount. When a disease stops circulating in a region, it’s considered eliminated in that region. Polio, for example, was eliminated in the United States by 1979 after widespread vaccination efforts.
If a particular disease is eliminated worldwide, it’s considered eradicated. To date, only one infectious disease that affects humans has been eradicated. In 1980, after decades of efforts by the World Health Organization, the World Health Assembly endorsed statement declaring smallpox eradicated. Coordinated efforts rid the world of a disease that had once killed up to 35% of its victims and left others scarred or blind.
So we administer vaccines to increase community immunity. One of the major tools to increase community immunity is “Ring Vaccination”. In Ring Vaccination we track down every person who could have been exposed to a patient and vaccinated as quickly as possible, effectively corralling the disease and preventing its further spread. Thus when we increase community immunity for certain disease, we mean that virus/microbe cannot infect that community. Virus/microbes might be present in the community it is just that they cannot infect.
When we achieve this on global scale, we can safely say that we have successfully eradicated that disease.
But there are major concerns before a disease is declared eradicated. Some of them are listed below:-
- We assume that particular disease transmit only through humans. If it is not so then it becomes difficult to control the disease. Similar case happened with “Yellow Fever”. Yellow Fever infects humans as well as monkeys. If a mosquito bites an infected monkey it can easily spread the same to humans. In fact the discovery of animal reservoir for Yellow Fever derailed its eradication efforts in the early 1900s.
- Some viruses/microbes are adaptive. They continuously change. In this situation we have to continuously evolve our vaccines. Same is the case with Polio. Currently there are three strains of the vaccines.
- It becomes easier to control the disease if it is visible and time from exposure to the initial appearance of symptoms is fairly short unlike HIV where the virus can say inside the body up to 10-15 years. In this case we cannot guarantee elimination. (There is difference between AIDS and HIV +VE)
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I was quite restless. She was not turning up in the library and I was unable to figure out why. Did I do something wrong? I asked my friends about the exams but there were none. I was confused as what to do. But somehow my mind was certain that she will come in a day or two. And to my relief she did come but after a week! What a relief that was! I thought I got into heaven. But alas everything had changed.
After that dreadful day, she had started avoiding me. She started changing the route by seeing me. I was trying hard to figure out what went wrong but she didn’t give me an opportunity and I couldn’t dare. Now instead of smile there was sternness on her face. She also started using a different route to the library. I don’t blame her. When I think what I would have done if I were in her place, probably I would have done the same thing. How can I expect a girl to say yes in just two-three meet? I was foolish enough to give a friendship card on the third day of meet. Of course anybody would have done the same thing. Now almost a month has been passed. I still sit at the same table. But she has changed the place, far away from me, where I couldn’t see her. Each day passes by and I think I will ask for forgiveness. Her exam is just two weeks ahead and I am pretty sure that she wouldn’t come after that. My mind constantly nags me to ask for apology. I am just waiting for her anger to soothe. But I don’t see anything. The irony of the life is that you don’t get what you want and you only add liabilities in life.
The Human Resource Development Ministry is all set to go ahead with its plan to conduct a common engineering entrance examination from 2013, but the first nation-wide test may only cover technical institutions funded by the Centre.
ISEET : Indian Science Engineering Eligibility Test – 2013
Tentative date of examination:- 22 Feb 2013