Polio was one of the most feared diseases of the 20th century. In 99% of cases, it causes no symptoms or very mild symptoms and may go effectively unnoticed, making it easy for people to be unwitting carriers and spreaders of the virus and leading to an explosion of polio epidemics in the early 20th century as transport improved, population density in cities increased and it became easier for a virus like polio to reach a critical mass of people. Meanwhile, in that last 1% of sufferers polio infects the spinal cord, leading to paralysis or death. Even worse, young children tends to be particularly susceptible, leading to polio becoming known in some areas as infantile paralysis disease. There is still no known cure for polio.
In 1952 in the United States alone, polio caused 3,145 recorded deaths and 21,269 recorded cases of mild to disabling paralysis.
Happily, in the mid 1950s polio vaccines were developed by Jonas Salk and Albert Sabin (the Sabin version has traditionally been the most used but has a 1 in 750,000 chance of giving the recipient polio, remembering that most of those who do get infected will never notice it; Salk’s intravenous vaccine is more expensive to produce but risk-free and has now largely replaced the Sabin version). These vaccines quickly went into use in the Western world. Czechoslovakia, with the advantage of a small territory to cover and Soviet rigor in distributing vaccines, became the first country to claim eradication of polio as early as 1960. By 1980, instead of millions of polio cases a year, “only” an estimated 400,000 cases a year occurred worldwide and “only” an estimated 4,000 dead or paralyzed victims. By 1994, the Americas were certified polio-free by the World Health Organization and by 2002 the same certification applied to Europe.
India has long been one of the countries worst-affected by polio, with the extremely densely packed population, poor hygiene standards and widespread poverty forming the perfect opportunity for the virus to be spread around. The Indian government made a major effort to combat the disease, but by 1998 there were still hundreds of reported cases a month (cases where someone was sick enough to go to a doctor to be reported, which would largely be in that 0.5-1% of death and paralysis cases), peaking at around 800 per month at the height of the wet season, the best breeding ground for the virus.
1998 was the turning point however, with India instituting “national immunization days” for polio to make the final push to eradicate the disease. In 2009, the total number of reported cases fell to 741. Only 42 reported cases occurred in 2010. The last reported case was in January 2011, and the first time since polio was identified not a single case has been reported in India through the entire wet season. It is estimated by the Indian government and the World Health Organization that between 95 and 98% of Indians are vaccinated against polio. The vaccine alone has done the trick; it would be hard to argue that significant strides have been made in otherwise improving the conditions that let the virus thrive in India. If anything, those conditions have become more intense.
One of the key factors in India’s vaccination program has been an effort to combat misinformation. One of the six “frequently asked questions” on the website for India’s polio vaccination program dismisses the rumor that the vaccine can cause impotence. Another stresses that the vaccine has been thoroughly tested both internationally and in India. Without these efforts, it is unlikely that the Indians could have managed to get the vaccination rate high enough to prevent the virus continuing to do the rounds of the unprotected population. The difference between 90% and 95% of the population agreeing to be vaccinated may be only 5% of the population but it halves the number of unprotected people and halves the chance of an infected person passing the virus on.
Nigeria serves as the cautionary tale. Polio was on the ropes in Nigeria when Islamic fundamentalists found common ground with certain groups in US society and declared in 2003 that vaccines are a moneymaking plot by Western medical companies (this is not generally a problem in the Muslim world, it must be said; Saudi Arabia’s insistence that all pilgrims to Mecca be vaccinated against polio has played a very important role in spreading the importance of vaccination in the developing world).
Remembering that infants and children are disproportionately victimized by this disease, the effects of a stop to vaccination in Nigeria were felt quickly. Two-thirds of the world’s reported polio victims in 2004 were in Nigeria and undoubtedly many, many more went unreported. Even worse, refugees fleeing Nigeria reintroduced polio into 12 countries where polio was previously eradicated. A new President in 2007 who made polio vaccines a priority turned the tide, and there have been only a dozen or so reported cases this year to date, but any letup in vaccination endangers everyone. Indonesia had 303 cases in 2005, thanks to an influx of the aforementioned Nigerian refugees. Had Indonesia let its vaccination program lapse after eradicating polio a decade earlier, this many infected people could easily have re-established the disease for years. Happily, this was not the case, and Indonesia has recorded no new cases since.
More recently, countries including China and Australia have had recorded polio cases due to travelers arriving from Pakistan and India carrying the virus. As in Indonesia, high vaccination rates prevented these outbreaks from spreading.
The eradication of polio in India is an important step towards the final eradication of a major infectious disease worldwide, and also an important reminder of why vaccination is important. Just because people in the West no longer know anyone paralyzed by polio or killed by measles doesn’t mean those diseases are any less dangerous- it just means that up until now, we’ve done a good vigilant job of protecting ourselves. But it only takes one unlucky infected traveler or group of travelers to risk throwing all of that away if we let irrational fear get in the way of vaccination.
Remember kids, there’s not a single reputable study that shows a vaccination increases the risk of autism, and any amount of such studies to contradict that idea. The only thing vaccination and autism have in common is that the first signs of autism tend to show up not long after the age most kids get vaccinated. By the same token, you might as well claim alphabet blocks cause autism. Don’t let Jenny McCarthy tell you otherwise.
(Photo credits: Gates Foundation and Wikipedia).
