Counties in California, New York and Maryland detected their first measles cases of the year. The CDC has warned travelers to be vigilant as spring break begins.

Cases in the ongoing measles outbreak have risen to 258 across Texas, New Mexico and Oklahoma, and state health departments are urging more people to get the measles-mumps-rubella vaccine.

As Texas' measles outbreak grows, many North Texas doctors fear this is just the beginning, thanks to the increased vaccine hesitancy.

Measles are surging in Texas, with experts warning no sign of slowing until at least May. The outbreak has now spread to its third state, Oklahoma.

Texas and New Mexico on Tuesday reported an increase of 28 cases of measles in the last five days, bringing the total known infections to 256 in the two states since an outbreak began in late January.

Philadelphia hospital patients were also warned about possible exposure to the highly contagious virus just days after a warning for Dulles airport travelers.

Measles is caused by a highly contagious virus that's airborne and spreads easily when an infected person breathes, sneezes or coughs. It is preventable through vaccines, and has been considered eliminated from the U.