June 5 (UPI) -- The number of measles cases in the United States surpassed 1,000 Wednesday, a milestone Health and Human Services Secretary Alex Azar called "troubling."
The Centers for Disease Control and Prevention said 1,001 people have been sickened by the contagious disease in 2019. The agency made the announcement two days after its regular weekly outbreak update.
On Monday, the CDC said 981 illnesses had been reported.
"The 1,000th case of a preventable disease like measles is a troubling reminder of how important that work is to the public health of the nation," Azar said of the HHS' efforts to promote safety and vaccinations.
"We cannot say this enough: Vaccines are a safe and highly effective public health tool that can prevent this disease and end the current outbreak," he added.
As of Thursday, 26 states have reported cases to the CDC. Outbreaks, defined as three or more cases, currently center in Rockland County, N.Y.; New York City; Michigan; Butte, Los Angeles and Sacramento counties, Calif.; Georgia; Pennsylvania; Maryland; and Washington.
The occurrences are largely linked to travelers who returned from countries with large measles outbreaks, including Israel, Ukraine and the Philippines. The CDC said the majority of those infected in the United States were unvaccinated
The agency said the virus can spread when people within a community remain unvaccinated, and when people arrive in the United States after contracting the virus abroad.
Measles spread among unvaccinated people in Orthodox Jewish communities in New York State, New York City, and New Jersey after travelers returned from Israel with the virus. As a result, New York City has ordered mandatory vaccinations, and religious leaders have urged their followers to get vaccinated.
The symptoms of measles usually appear between seven and 14 days after infection. The signs include high fever, couch, runny nose, rash, and red, watery eyes.
Ed Adamczyk contributed to this report.