BEIJING — The State Department issued a health alert on Friday to American citizens living or traveling in China, advising them to seek medical attention if they experienced “auditory or sensory phenomena” similar to those experienced by American diplomats evacuated to the United States.

The alert, posted on the department’s website, said those who suspected that they had such symptoms should not try to locate the source of any “unidentified auditory sensation” and should seek medical care as soon as possible.

More than two million American citizens travel to China each year, and about 175,000 Americans hold Chinese resident visas.

The advisory came after at least two employees at the United States Consulate in the southern city of Guangzhou, who showed symptoms similar to those suffered by American diplomats in Cuba in 2016, were flown out this week for testing by specialists at the University of Pennsylvania.