At least 89 cases have been reported in the last four months alone, compared to an annual average of around 50.
Most of those are linked to a big outbreak in Europe, where more than 6,500 people across 33 countries have fallen victim to the disease.
Travellers are catching the highly contagious illness while on vacation, then bringing it back to the U.S. when they return home.
There have been particularly bad outbreaks in Utah, where nine children were infected after one spent time in Poland, and in Minnesota, where 21 fell ill after one child contracted the condition in Kenya.
American children have been vaccinated against the disease for more than 50 years.
But in Europe immunisation rates have fallen over the last decade after a discredited study linked the MMR vaccine to autism, sparking the outbreak.
Now international health officials are warning all travellers to get the recommended two doses of vaccine before they go abroad.
Dr Cuauhtemoc Ruiz Matus, an immunisation expert with the Pan American Health Organisation, said: 'The risk of getting infection is very high.' Read More


