Transcript for Health emergency in Pacific Northwest involving measles outbreak
I we have been following the real concern over measles, and tonight, a public health emergency has been declared in Washington state. And authorities say there is a common thread. They also say if someone infected visits a store or a restaurant, a school, that that virus then hangs in the air for up to two hours. ABC's chief national correspondent is in Vancouver, Washington, for us. Reporter: That measles outbreak growing by the hour. My biggest concern as the numbers increase is that we lose a child to this disease, and something that is completely, utterly preventable. Reporter: Tonight, at least 30 of 35 patients sickened with the measles in Clark county, Washington, were never vaccinated. There are an additional 11 suspected cases. Experts here warn the public might have been exposed at a recent Portland trailblazers game, at Portland's airport, at area schools, a local Costco and IKEA. Washington state has been called a "Hot spot" because of its anti-vaccine movement. It has one of the lowest vaccination rates in the country. But it's not just in the northwest. New York state has registered 184 measles cases in the last four months. The highly contagious virus can live on surfaces or in the air for up to two hours. Callie kaito's 2-year-old daughter can't get the vaccine. How does this outbreak affect you? I'm worried. I am very worried. Reporter: Measles had all but disappeared in the U.S. After widespread use of the vaccine. But in recent years, it's made a comeback. The number of measles infections has tripled just since last year, David, and now the world health organization considers reluctance to vax Nate one of his top ten global threats for 2019. David? ABC's Matt Gutman with us tonight. Thank you.
This transcript has been automatically generated and may not be 100% accurate.