SEATTLE — The measles outbreak has spread across the United States, with over 700 confirmed cases. There have been 72 cases in Washington state, with one of those in King County. This is the highest total reported in 25 years. 

Dr. Helen Chu from UW Medicine explained why the measles are spreading at such an alarming rate, and how people can further protect themselves. The problem, she said, is there are pockets of unvaccinated people who put others - especially children under the age of one who haven't received their MMR shot - at risk. 

"It's largest number of cases in 25 years of a disease that's completely vaccine-preventable," Dr. Chu said.

Related: US measles count rises to 764, driven by New York outbreaks

The most recent case of measles in Washington state involved a Canadian tourist who visited several Seattle attractions, including the Space Needle. In a case like that, Dr. Chu says the Department of Health will try to notify people who visited the same places around the same time and alert them to the possible exposure. 

However, unless someone becomes "very sick," those who suspect they have the measles are told to stay home because there is no treatment. 

"If you're very sick you can go to the hospital," Dr. Chu said. The hospital can do supportive care like giving vitamin A or treating bacterial infections. "There's actually no therapy effective against measles," Dr. Chu said. "The best thing to do is to get the vaccine," she said.

Related: Washington state limits exemptions for measles vaccine

Related: Oregon House OKs tough vaccine rules over vocal opposition

Watch New Day Northwest 11:00 weekdays on KING-TV Ch.5 or streaming live on KING5.com. Connect with New Day via Facebook, Twitter, Instagram.