(CNN) At least 314 cases of measles have been reported in the United States since January 1, according to national numbers shared Monday by the Centers for Disease Control and Prevention.

That's 46 more than the number reported by the agency last week and includes illnesses reported by state health departments to the CDC through March 21.

This year's number is 58 shy of the 372 cases reported in all of 2018, the second-highest number in more than two decades.

CDC spokesman Jason McDonald wrote in an email that the agency does not "try and predict how many cases we will have in any particular year or when we might surpass the number of cases that occurred in a previous year."

Measles is a highly contagious, vaccine-preventable respiratory illness characterized by a rash of flat red spots. Symptoms may include fever, cough, runny nose and watery eyes.