April 15 (UPI) -- The measles outbreak in the United States has grown to its second-highest level in a quarter-century, the U.S. Centers for Disease Control and Prevention said Monday.
There have been 555 cases reported so far in 20 states, the CDC said. The number has risen by nearly 200 in just two weeks as many Americans refuse to get their children vaccinated for religious or anti-government reasons.
The current level represents the most measles cases in 25 years.
"I'm obviously very concerned about the size and also acceleration of the current outbreak," Dr. Nancy Messonier, director of the CDC National Center for Immunization and Respiratory Diseases, said. "This is not going to stop on its own."
The new cases were reported in Arizona, California, Colorado, Connecticut, Florida, Georgia, Illinois, Indiana, Kentucky, Maryland, Massachusetts, Michigan, Missouri, Nevada, New Hampshire, New Jersey, New York, Oregon, Texas and Washington.
The greatest outbreaks, three or more cases, have been seen in New York, Washington state, New Jersey and California, officials said.
The World Health Organization said Monday there were more than 110,000 measles cases worldwide for the first three months of 2019 -- an increase of nearly 300 percent over last year.
New York City has declared a public health emergency and required some to have their children vaccinated, or face a $1,000 fine.
Since 2000, only 2014 saw more cases (667) by this point of the year. Officials said the majority of cases occurred in people who are not vaccinated.
Many of the measles cases last year were concentrated on Orthodox Jews who traveled to Israel, where a large outbreak occurred. Officials said 82 people brought in measles from other countries last year, the most number of imported cases since 2000. Ukraine and the Philippines have also seen large measles outbreaks.