WCNC CHARLOTTE, N.C. - There's growing concern over measles outbreaks across multiple states - and experts say it reflects a larger trend across the United States.

There are several reports of new cases in South Carolina. Many of those infected had not been vaccinated. 

Measles is one of the world's most contagious diseases. It is an airborne infection that attacks the respiratory tract and spreads through the body. It is spread easily when an infected person breathes, coughs or sneezes. Prior to the introduction of the Measles vaccination in 1963, the disease caused an estimated 2.6 million deaths per year, according to the World Health Organization.

Health officials say the rise in new cases is due to falling vaccine rates and rising immunization hesitancy. As more people choose not to vaccinate, we risk losing herd immunity - the protection a community gets when enough people are immune. This generally protects more vulnerable populations. 

Doctors warn that measles can lead to serious complications like pneumonia, brain swelling, even death - especially in children. This outbreak is a reminder that diseases we once thought of as nearly gone can come back if we let our guard down.