Victories in disease eradication
May 1, 2012
Perhaps science’s greatest achievement of the 20th century was the eradication of the virus that causes smallpox. Smallpox was an absolutely awful disease that killed about half a billion people in the 20th century alone. Up to one-third of individuals who became infected with the virus died, and those who survived would often suffer debilitating consequences such as blindness. The death rates were even higher in children.
Today, our kids can grow up without having to worry about this nasty disease, primarily due to an eradication program initiated in 1958 by the World Health Organization. This aggressive and globally coordinated vaccination campaign was highly successful and culminated in a declaration in 1980 that this global scourge had been completely eradicated from society at large. Countless lives have been saved ever since. The smallpox virus now exists only in frozen vials in two highly secure laboratories in the United States and Russia. Concerns that the virus could get into the hands of a bioterror group have led to mounting political pressure to destroy these last remaining vials. Let’s hope that happens soon. But if the worst ever happened, we would be able to deploy the smallpox vaccine to mitigate the impact.
Clearly, the global elimination of an entire disease is the pinnacle of infectious disease control. Therefore, it is surprising to me that a second disease eradication milestone has received very little play in the popular press. I refer to the announcement last year by the United Nations that rinderpest had been completely eradicated. Rinderpest was an infectious viral disease that is highly lethal in cattle and pigs (but does not infect humans). Some forms of the disease were lethal in 95 percent of animals, and regular epidemics used to wipe out entire herds essential for the livelihoods of many cultures. This was a significant problem in Europe in the early 20th century and remained a major problem in many parts of the world until very recently. In poorer regions, especially Africa, cattle are a primary source of food and clothing and are also essential for plowing and hauling products to markets, so rinderpest epidemics were devastating.
The campaign to eradicate rinderpest began in 1945 as an initiative by the Food and Agriculture Organization of the United Nations. Progress was initially very slow but gathered steam as scientists developed new technologies to fight the disease. These included the invention of new diagnostic methods to enhance disease surveillance and the development of improved vaccines that could be delivered quickly and cheaply. Despite these advances, the battle with this disease has been difficult and resulted in much false hope. Early celebrations of rinderpest eradication in the 1970s proved to be premature when they were followed by the rapid re-emergence of the disease. One of the problems was that nomadic tribes were freely crossing international borders with herds of cattle that served as disease reservoirs. Another problem was that animals suffering from rinderpest were released from the herds, thereby helping to propagate the disease. There were also cases of cattle herders who thought the vaccine caused the disease and refused to have their animals vaccinated. It is for these reasons that authorities waited 10 years since the last confirmed case of rinderpest in Kenya in 2001 before declaring eradication.
Despite the victories over smallpox and rinderpest, there are still plenty of battles ahead. We are in the midst of a raging HIV pandemic (see last month’s Petri Dish), and ancient diseases, such as tuberculosis and malaria, remain critical problems in the world today. Scientists across the globe are working at a frantic pace to develop new vaccines and drugs to fight these major killers, and there is growing hope that more diseases can be added to the “eradicated” list. In this regard, it is comforting to learn that India has marked its first year without a single case of polio. This is a major achievement for the Global Polio Eradication Initiative, although polio still retains a grip in Afghanistan, Pakistan and Nigeria. Importantly, the victory over rinderpest demonstrates that the eradication of smallpox was not a fluke and offers great hope in the fight against infectious disease in general.
One last thought: The battle against rinderpest took 65 years and is believed to have cost approximately $5 billion. There is no doubt that this is a lot of money, but it pales in comparison to the well over $1 trillion per-year price tag for our health care system in the United States. Preventing disease through vaccination – or even better eradicating it completely – is a well-spent investment in our future.
David L. “Woody” Woodland, Ph.D. is the Chief Scientific Officer of Silverthorne-based Keystone Symposia on Molecular and Cellular Biology, a nonprofit dedicated to accelerating life science discovery by convening internationally renowned research conferences in Summit County and worldwide. Woody can be reached at 970-262-1230 ext. 131 or firstname.lastname@example.org.