Читать книгу Modern Epidemics - Salvador Macip - Страница 35

Poliomyelitis, more simply known as polio, is a disease that causes paralysis in 1 per cent of those afflicted by it because the virus responsible destroys nerves. The most frequent kind is paralysis of the legs, but if the nerves controlling the muscles related with breathing are affected, it can be fatal. Some kinds of paralysis reverse in the first year but, after that time, few improve. It’s calculated that, at the beginning of the twenty-first century, between 10 and 20 million people had survived polio, with varying degrees of sequelae. In 90 per cent of cases there are no symptoms.

The disease was discovered in 1840 and the virus that causes it, the poliovirus, in 1908. It’s mainly contracted through water contaminated with faeces of infected people (where the virus can live for weeks), although saliva can also be a source of transmission. The number of cases of polio increased spectacularly at the beginning of the twentieth century, which spurred on the quest to find a vaccine. Jonas Salk achieved the first (1952) and Albert Sabin the second (1962). In 1988, there were 350,000 cases of polio in the world. It was initially expected that the disease would be eradicated by 2000, but that didn’t happen. In 2007, there were 1,315 cases recorded and, in 2008, another 1,643; despite everything, this was a remarkable decline in just twenty years. The year with the fewest cases was 2001: just 483 were recorded. Progress seems to have stalled a little since then.

Since the turn of the century, $6,000 million have been spent on preventing and controlling polio. In early 2009, a new initiative was announced to eliminate it from the few places where it still exists (especially Nigeria, India, Afghanistan and Pakistan) and thereby to make it history’s second eradicated disease. An investment of $630 million was made, donated by the Bill & Melinda Gates Foundation, Rotary International groups and the governments of Germany and the United Kingdom, which was distributed by the Global Polio Eradication Initiative (GPEI), part of the WHO. The strategy was mainly to increase vaccination of small children, as this is the most effective preventative. Although the hoped-for results haven’t yet been completely achieved, the experts are optimistic and believe that there is every chance that polio will end up disappearing altogether.

Of the three existing variants of poliovirus, type 1 is the most aggressive. In 1999, type 2 was eradicated. Only a few samples were kept for study or continued production of vaccines. This might have been recorded as the second microorganism to be eliminated from the planet if it weren’t for the fact that, in 2005, it made a surprise reappearance in the middle of Africa. By 2008, it had resulted in thirty cases of paralysis and, by the middle of 2009, a further hundred, together with the possibility that it would start spreading to other areas. The origin of these new outbreaks was the vaccine that was supposed to eliminate it.