(Reuters) – The number of confirmed cases of measles in the United States this year jumped by nearly 20 percent in the week ended April 11, in the country’s second-worst outbreak in nearly two decades, federal health officials reported on Monday.

As of April 11, the U.S. Centres for Disease Control and Prevention (CDC) recorded 555 cases of the disease since the beginning of the year, up from 465 cases confirmed by April 4. The cases were found in 20 states spanning the country.

The measles virus is highly contagious and can lead to complications and death, particularly in children. The CDC report did not say whether there have been any fatalities.

The U.S. outbreak is part of a worldwide rise. The World Health Organisation reported on Monday that global cases had risen nearly four-fold in the first quarter of 2019 to 112,163 compared with the same period last year.

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