Officials in Multnomah County, Ore., announced last week that a person known to be contagious with measles attended a Portland Trail Blazers home game against the Charlotte Hornets on Jan. 11 and that others who were inside Moda Center between 5:30 p.m. and 11:30 p.m. that night could have been exposed.

On Tuesday, officials in Clark County, Wash. — located across the Columbia River from Portland — on Tuesday increased the number of confirmed measles cases in the county to 23, declaring a public health emergency. The infected people visited schools, churches, businesses and Portland International Airport along with the NBA game, the officials said, and most had not been immunized against the highly contagious disease, which can linger in the air even after an infected person has left the premises.

A sold-out crowd of 19,393 watched the Blazers defeat the Hornets on the night in question. Officials say anyone who has not been immunized from the disease is especially at risk.

Though experts say more people in the area could be confirmed as having measles in the coming days, the outbreak has not gotten to the point where sporting events have been affected. In 1989, measles outbreaks at Siena College and the University of Hartford led ECAC North Atlantic Conference officials to ban spectators from the conference’s postseason basketball tournament at the Hartford Civic Center. Because a member of the Saints' basketball team came down with measles, Siena would play its final nine games of the regular season in empty stadiums, but it still advanced to the NCAA tournament for the first time in program history after defeating Boston University in the conference tournament championship game.

“At first it was different, new,” Siena guard Marc Brown told the New York Times. “But now, it’s starting to wear on me. I’m a little flashy; I like to make a nice pass and hear the crowd cheer. But no one cheers.”

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