FILE PHOTO - One-year-old Bella Huang cries as medical assistants secure her legs for a series of vaccines at the International Community Health Services clinic in Seattle, Washington, U.S., March 20, 2019. REUTERS/Lindsey Wasson

(Reuters) - U.S. health authorities recorded 75 new cases of the measles in the latest week, mostly in New York state, bringing the nationwide total to 839 cases in the country’s worst outbreak of the virus since 1994, federal health officials said on Monday.

The U.S. Centers for Disease Control and Prevention reported a 9.8% increase in measles cases as of May 10, a resurgence that public health officials have attributed to the spread of misinformation about the measles vaccine. Data are updated every Monday.

In New York, 66 cases were reported according to CDC spokesman Jason McDonald, with 41 in New York City and 25 in Rockland County, about 40 miles (64 km) north of New York city.

Health experts say the virus has spread mostly among school-age children whose parents declined to give them the vaccine, which confers immunity to the disease. A vocal fringe of U.S. parents, some in New York ultra-Orthodox Jewish communities, cite concerns that the vaccine may cause autism. Medical science has debunked those concerns.

While the 2019 outbreak has spread rapidly within New York, the virus has not spread to any additional states since the previous week, when Pennsylvania became the latest state to confirm at least one case.

Experts warn that the outbreak is not over as the number of cases approaches the 1994 total of 958. That was the highest number since 1992, when the CDC recorded 2,126 cases.

Although the virus was eliminated from the country in 2000, meaning the disease was no longer a constant presence in the country, outbreaks still happen via travelers coming from countries where measles is still common, the CDC says.

More than 40 people in 2019 brought measles to the United States from other countries, most frequently Ukraine, Israel and the Philippines, federal officials said.