DENVER — Arizona health officials on Thursday were tracking more than 1,000 people, including at least 195 children, who might have been exposed to measles as part of an outbreak that began at Disneyland in Southern California and has grown to 67 cases in seven states.

Arizona has seven confirmed cases of measles, and officials in three counties in the Phoenix area — Maricopa, Gila and Pinal — are asking residents who have not been vaccinated and who might have been exposed to stay home from school, work or day care for 21 days.

The announcement comes as thousands of people are arriving in Phoenix for the Super Bowl on Sunday.

“This is a critical point in this outbreak,” the state health director, Will Humble, wrote on his blog. Any missed cases, he wrote, could cause “a long and protracted outbreak.”

In a conference call with reporters, a Centers for Disease Control and Prevention official advised anyone with symptoms not to attend the Super Bowl. “The very large outbreaks we’ve seen around the world often started with a small number of cases,” said the official, Dr. Anne Schuchat, director of the agency’s National Center for Immunization and Respiratory Diseases.