Britain’s polio-free status could be at risk for the first time in almost two decades after several samples of vaccine-derived poliovirus were found during routine London sewage testing.
Here’s what’s known so far:
1. Is polio back in Britain?
We don’t yet have a clear idea how wide the transmission is. No cases of polio or associated paralysis have been reported so far. Health officials said the sewage findings are concerning but the risk to the public overall is low.
Many developed countries -- Britain included -- had large epidemics of poliovirus in late 1940s and 1950s. The outbreak slowed down in the 1960s thanks to the introduction of vaccines and improved hygiene.
The UK’s last case of wild polio was in 1984 and the country was declared polio-free in 2003.
2. What is polio?
It is a rare disabling and life-threatening disease caused by a virus that spreads easily among people. Young children are the most at risk, but adults can also have the disease.
Wild polioviruses have been eradicated in most parts of the world except in Afghanistan and Pakistan, where they remain endemic. The vaccine-derived poliovirus -- which originates from live attenuated polio viruses contained in oral polio vaccines -- still trigger outbreaks, most recently in Ukraine, Israel and some African countries.
3. How do you get polio?
Poor hand hygiene is the main spreading route. The pathogen multiplies in the intestine and infected people excrete large quantities of virus in their feces. Poliovirus can spread when an infected person does not properly wash their hands after using the toilet and then touches what is eaten by others.
Less commonly, the virus can be passed on through coughing and sneezing.
4. What are the symptoms of polio? Is it lethal?
Most people with polio are asymptomatic. Some of them will experience a flu-like illness with fever, a sore throat and headache, but these symptoms will typically disappear without any medical intervention.
In a small number of cases -- between 1 in 100 to 1 in 1000 infections -- the poliovirus attacks the nerves in the spine and base of the brain. This can lead to paralysis, usually in the legs, that develops over hours or days. Symptoms include rapid onset of weakness in a limb. Movement will often slowly return over the next few weeks and months but many patients are left with persistent problems.
Polio can be life-threatening if the breathing muscles are affected.
5. How is it treated?
There is no cure for polio and treatment can only alleviate the symptoms. Doctors can use heat and physical therapy to stimulate the muscles and antispasmodic drugs to relax them. However, permanent polio paralysis cannot be reversed. The best method to stop polio, therefore, is through prevention.
6. When should babies have their polio vaccine?
Polio vaccines almost always protect a child for life after multiple doses.
In the UK, the shot is part of a routine childhood vaccination schedule offered by the National Health Service. Babies are given the primary course at 8, 12 and 16 weeks old, and boosters will follow when they reach pre-school as well as during their teenage years.
A worrying sign is that the polio vaccination rate has been slowly declining in the UK, according to data from the NHS. About 94% of two year-olds are considered to be protected. London faces a wider challenge, as its infant vaccination rate is lagging behind the national level, with 89% of two year-olds immunized.
Officials urged people to ensure polio vaccines are up-to-date, especially for young children.
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