(NBC NEWS) An outbreak of measles that started in California’s Disneyland probably came from overseas, carried either by a foreign tourist or by an American coming back with the virus, a top federal health official said Thursday.

The virus has now infected 94 people in eight states, and 67 can be clearly linked to Disneyland, California health officials report. Because measles is so contagious, more cases can be expected.

“We don’t know exactly how this outbreak started but we do think it was likely a person infected with measles overseas,” Dr. Anne Schuchat of the Centers for Disease Control and Prevention told reporters.

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