More than 100 cases of measles have been diagnosed this year in 21 U.S. states and the District of Columbia, the U.S. Centers for Disease Control and Prevention reported Thursday.
As of July 14, 107 people had contracted the viral infection in Arkansas, California, Connecticut, Florida, Illinois, Indiana, Kansas, Louisiana, Maryland, Michigan, Missouri, Nevada, New Jersey, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Tennessee, Texas, Washington, and the nation's capital.
Measles is a highly contagious virus that spreads through the air via coughing and sneezing. The illness starts with a fever, runny nose, cough, red eyes and a sore throat. It's followed by a rash that spreads over the body. While the disease is treatable, the CDC said, one or two out of every 1,000 children who get measles die from complications.
This year's outbreak is on pace to surpass last year's, when 118 people from 15 states and the District of Columbia were reported to have measles. In 2016, 86 people from 19 states contracted the illness.
The CDC said the majority of people who contracted measles were unvaccinated. Prevention is key, because the virus can be spread easily.
The measles virus can live for up to two hours in an airspace where the infected person coughed or sneezed, according to the CDC. Measles is so contagious that if one person has it, 90 percent of unimmunized people in close contact with the infected person will also become infected.
In 2015, the United States experienced a large, multistate measles outbreak linked to an amusement park in California. The outbreak most likely started with a traveler who became infected overseas, then visited the park. The source of the infection was never identified.
The CDC recommends children get two doses of the vaccine, starting with the first dose at 12 to 15 months of age, and the second dose at 4 through 6 years of age.
Lifetime effectiveness means adults vaccinated as children don't need to be revaccinated.