Americans have been warned to take precautions before travelling to 31 countries due to the rise in polio cases. The US Centers for Disease Control (CDC) has issued the level two alert, advising people to make sure they’re up to date on their polio vaccines. People in the US who plan to travel to the listed countries, including the United Kingdom and Spain, are eligible for a single-dose booster of the vaccine. Polio, officially called poliomyelitis, was one of the most worrying childhood