Ontario's chief medical officer of health says six infants have been born with congenital measles since an outbreak began last fall, adding they were infected in the womb through mothers who were not vaccinated.

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

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,