Wednesday, 22 February 2012

IMFW: Poliomyelitis

Long time no Interesting Medical Fact of the Week! In fairness, this is the first time in several months in which I have failed so abjectly to produce an IMFW on a Monday. I don't have any excuse at all, so without further ado:

Today's Interesting Medical Fact of the Week is focusing on Poliomyelitis, commonly known as polio. When I was a child, the combination of the name of the illness and the fact that the vaccine is delivered on a sugarlump meant that I had a vague conception of polio as a round, white germ with a hole in the middle. At least I didn't think of it as a kind of posh horsey bacteria.* Or a car.

Quick recap of polio: it's a highly infectious viral disease. About 90% of people who are infected will not have any symptoms. 5% will have only very mild symptoms, like a cold or 'flu. 1% will have a more serious episode of 'flu-like symptoms, often with muscle stiffness and meningitis. And only about 0.1% of cases will develop paralytic polio, in which the virus attacks the central nervous system and produces the "classic" polio symptoms which most people would recognise: the muscles of one or more limbs become extremely weak and finally paralysed. In cases where the virus invades the bulbar region of the brainstem, it may cause difficulty breathing, speaking, and swallowing.

Although there are vaccines for polio, there is no cure. Patients who are unable to breathe independently can be kept breathing using a negative or positive pressure ventilator until they have recovered, although in some cases polio survivors may need to use one of these devices for the rest of their lives. About half of patients with paralytic polio do recover completely, but around a quarter are left with significant permanent disability.

Since a global effort to eradicate polio began in 1988, the number of annual cases of polio being diagnosed has reduced by 99%. The initial eradication initiative aimed to eliminate polio by the year 2000; twelve years later, the disease is still clinging on in a few countries and is still considered endemic in Afghanistan, Pakistan and Nigeria. The last case in India was in January 2011, and the country is hoping to be certified as free from endemic polio shortly.

Efforts to eliminate the disease in these countries have been hampered by instability, as well as rumours in Nigeria that the vaccination effort was a Western conspiracy to spread HIV and sterilise Nigerian girls. Vaccination was banned for several years, leading to a massive upsurge in infections in Nigeria and the transmission of polio back into neighbouring countries. Vaccination boycotts have also taken place at various times in India; and in Pakistan and Afghanistan the Taliban have issued fatwas against polio vaccination.

In 2011 there were 649 cases of polio reported worldwide, with over half of these from polio-endemic countries, compared to around 350,000 in 1988.
*Not least because it's a virus.

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