Doctors didn't understand how the polio virus entered the body, and they didn't know how to treat it.
Of the three strains of wild polio virus, P1, P2 and P3, P2 was eliminated in 1999.
Allegedly, the vaccine makers grew the polio virus in kidney cells from chimps infected with the virus.
Over the past decade 15 billion doses of polio vaccine drops have been given and there have been 200 confirmed cases of circulating vaccine-derived polio virus.
Only last week an emergency vaccination programme was ordered in Cairo after samples of the polio virus were found in sewage - the strain matches that in southern Pakistan.
In separate American laboratories, two men working separately -- Dr. Jonas Salk and Dr. Albert Sabin -- were determined to defeat the polio virus, to end the heartbreak.
The 254-nanometer light kills the hardy waterborne polio virus, rotavirus (which causes vomiting, diarrhea and dehydration), the bacterium that causes cholera, the virus that gives rise to hepatitis A, and cysts of cryptosporidium (a nasty parasite).
The oral polio drops used in the developing world are made from a live weakened virus - which carries a minute risk of causing polio in every million doses given.
Infected travellers had carried the virus to nearly 20 previously polio-free countries causing more than 1200 polio cases.
Back then AIDS vaccine research was focused on stimulating the immune system to produce antibodies against the virus, a standard strategy that worked for polio and other diseases.
Twenty years after the global outbreak of AIDS, no one has developed an effective vaccine against the HIV virus, a far more cunning foe than polio, smallpox or measles.
The idea that it was a CIA plot, for instance, or the idea that an American-led polio vaccination campaign unintentionally gave a million Africans a chimp virus in the late 1950s.
Today marks the a year since the last case of new polio infection in India a major step toward eliminating the virus there.
These vaccines resemble those used against smallpox or polio in that they use a piece of the target -- there a virus, here a cancer cell -- to boost the immune systems ability to find and attack those targets.
This is a now or never moment - kick polio off the planet over the next few years or face a humiliating retreat which could see the virus re-emerge in scores of countries.
The killing of eight polio workers in Pakistan in two days is a brutal reminder of the hurdles facing health teams trying to eradicate the virus from one of its few remaining strongholds.
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