After measles outbreak in Pennsylvania, New Jersey and Delaware, CDC concerned about virus

PHILADELPHIA (CBS) -- The number of measles cases in the U.S. continues to rise, and now there are renewed warnings from federal health officials. More cases of measles have been reported so far this year, in less than four months, than in all of 2022.

Officials at the Centers for Disease Control and Prevention are concerned that measles infections continue to rise in the United States.

As of April 18, 125 cases were reported in 17 states including Pennsylvania, New Jersey and Delaware.

The vast majority of cases occur in people who are not vaccinated or those whose vaccination status is unknown, and nearly half of all cases are in children under five.

"Parents, unfortunately, are withholding their children or delaying their children from being vaccinated against this disease," Dr. William Schaffner, an infectious disease specialist, said.

Doctors say measles is extremely contagious and they warn there's a misconception among some parents that it causes only mild illness.

"It is an absolutely nasty infection, and I would not wish a single child to have to experience measles," Schaffner said.

The most recent outbreak in Philadelphia in December and January involved nine people. That outbreak has officially ended , according to the city.

Measles symptoms include high fever, cough, runny nose, red eyes, white spots in the mouth and a rash that starts on the hairline and face and spreads.

"The measles virus can get down into your chest and cause pneumonia. Even more seriously, it can get into your brain and cause inflammation," Schaffner said.

Doctors say the best way to avoid infection is to get vaccinated.

Disease forecasters at the CDC have estimated that the U.S. would likely reach 300 cases of measles this year. That's more than most recent years. Measles is on the rise around the world as well.