The fast-spreading measles outbreak in the United States is reaching epidemic proportions with 555 cases recorded so far this year. More than 90 cases were reported last week alone.

No measles fatalities have been reported in the U.S. thus far.

The U.S. Centers for Disease Control and Prevention (CDC) said the large spike in measles cases places 2019 on track to be the worst year for measles since public health officials announced the eradication of this very contagious viral disease in 2000.

CDC has confirmed 555 measles cases from Jan. 1 through April 11, just four months into the year. At the rate the outbreak is spreading, it's all but certain the total number of cases for 2019 will exceed the total of 667 cases diagnosed in 2014. Health officials said this grim record might be set as early as next week.

CDC said that of the 90 new cases reported last week, 77 were in New York State. Fifty cases were reported in New York City with 27 were in Rockland County.

"I'm obviously very concerned about the size and also the acceleration of the current outbreak," said Dr. Nancy Messonier, director of the CDC's National Center for Immunization and Respiratory Diseases. "This is not going to stop on its own."

New York City Mayor Bill de Blasio last week declared measles a public health emergency and ordered mandatory vaccinations for people living in Brooklyn's Williamsburg neighborhood where the disease is spreading. The city government warns unvaccinated people living in the affected areas to get the vaccine or face fines.

Measles has been reported in 20 states since January. Outbreaks are ongoing in five areas: New York City, Rockland County, Washington D.C., New Jersey, California's Santa Cruz County, and California's Butte County. An outbreak is defined as three or more cases.

The CDC said travelers brought back the disease from places like Israel and Ukraine where large measles outbreaks are occurring. The World Health Organization (WHO) said there has been a 300 percent increase in measles cases worldwide to 112,000 from January to March from 28,000 year-on-year.

Ukraine has the highest number of cases over the past 12 months, with more than 72,000. Close behind it are Madagascar and India with more than 69,000 and 60,000 cases, respectively.

A highly contagious viral disease, measles can infect up to 90 percent of unvaccinated people exposed to it. CDC said the measles virus can live in the air for up to two hours after an infected person coughs or sneezes. This means people can be exposed to it without even realizing it.

It said 1 or 2 out of 1,000 children who get measles will die from it.