Since the development of the vaccine, perhaps the most effective public health measure we have yet devised, only one human disease has been completely eradicated from the world – smallpox. The last case was reported in Somalia in 1977. Eradication was the result of a deliberate and intense campaign, requiring almost complete vaccination of the population, especially in certain population dense areas. Countries such as India and Nigeria were among the last to achieve eradication. Some of the lessons learned were that very high compliance rates were needed and that even small communities could harbor the virus and prevent eradication.
Several decades later, at the beginning of the 21st century, we are on the verge of eradicating a second major human infectious disease, polio. Like smallpox, polio is a virus that has no major non-human host, so eradication is possible. The polio virus enters the anterior horn cells of the spinal cord, the lower motor neuron – cells that connect the brain to muscles. When those cells die muscles lose their connection causing weakness and atrophy. Vaccine campaigns have successfully eliminated polio from most countries, but the wild type of the virus remains endemic in Nigeria, India, Pakistan, and Afghanistan.
We have the potential, with one final push (which is being spearheaded by the World Health Organization – WHO) to eradicate wild type polio from the world, but these efforts are being hampered by politics and ideology.