Thousands of people, mostly children, in the U.S., Canada, and Mexico have contracted the vaccine-preventable disease this year.

An Ontario infant born prematurely and infected with measles has died in the first fatality of a growing provincial outbreak. Health officials say the baby contracted measles before birth and that the mother was unvaccinated.

A baby born prematurely to an unvaccinated mother has become the first measles patient to die in a measles outbreak that started in Canada last year. The infant died in Ontario, where nearly 2,000 cases have been reported,