• Infectious Diseases A–Z: Why it matters if U.S. loses measles elimination status

a group of young people's hands holding up the earth, the world, a globe

Measles outbreaks in the U.S. continue, making the number of cases reported in the country the highest since 1992. Measles were declared eliminated in the U.S. in 2000, but that status may be in jeopardy as infections spread.

"It's very frustrating. It is a long and arduous road to achieve measles elimination, and it is very likely the U.S. will lose that status," says Dr. Gregory Poland, director of the Mayo Clinic Vaccine Research Group. "We are nearly at the point of having ongoing measles cases and the virus circulating for a full year. That fits the criteria for losing measles elimination status. From an individual and public health point of view, we are going backward — not forward — in protecting ourselves against this disease."

Watch: Dr. Gregory Poland discusses measles outbreaks.

Journalists: Broadcast-quality sound bites with Dr. Gregory Poland are in the downloads. Please "Courtesy: Mayo Clinic News Network."

"In the year 2000, it was declared eliminated, meaning there was no virus circulating in the U.S," says Dr. Poland. "What has happened is because people reject vaccines, particularly measles, mumps and rubella vaccine, we start developing these larger and larger populations where people are susceptible to the disease. Then they go on vacation in a foreign country where they have measles, or somebody from that country comes to the U.S. and interacts with somebody who's susceptible. In the case of measles, it's like throwing a match on gasoline."

The outbreaks in the U.S. have been linked to travelers who brought the virus back from other countries. Globally, 181 countries are experiencing measles outbreaks. The World Health Organization says major outbreaks are taking place in countries with the lowest vaccination rates.

Dr. Poland says the measles virus is transmitted by air. "It's more deadly than influenza, and measles is the most contagious disease we know of.  If you and I were both susceptible to measles and somebody came into this room eight hours ago with measles, we would both get infected. It's that contagious."

And it's preventable with vaccine. In the U.S., the measles vaccine is part of the measles, mumps and rubella (MMR) vaccine series given to children. The Centers for Disease Control and Prevention recommends all children get two doses of the MMR vaccine, starting with the first dose at 12 – 15 months of age and the second dose at ages 4 – 6. Two doses of MMR vaccine are approximately 97% effective at preventing measles.