The Western Washington measles outbreak began on May 9, with residents of Pierce, King and Snohomish counties diagnosed after spending time at the Seattle-Tacoma International Airport.

This year, Washington has had 82 cases, or about 8% of the 1,077 cases reported in the United States, which prompted state lawmakers to ban exemptions to the measles, mumps and rubella vaccine except for religious or medical reasons. Most of the state’s cases were from a Clark County outbreak earlier this year.

This year, the U.S. has seen the most cases since 1992 and since measles was declared eliminated in 2000, according to the federal Centers for Disease Control and Prevention (CDC).

Measles, which can cause fever, rash and red, watery eyes, is highly contagious and spreads quickly through the air after a cough or sneeze. The virus can remain in the air for up to two hours after someone with the virus leaves the area.

Symptoms may appear starting from seven days after the first exposure to 21 days after the last exposure, according to the state health department. A rash typically appears 10 to 12 days after exposure.