(CNN) The Santa Clara County, California, health department said a person with measles visited Google's headquarters in Silicon Valley, which is in their county. The adult is a resident of San Mateo County.

cases were reported in Santa Clara County (one child and three adults), according to the As of April 10, California has reported 21 cases of measles this year. Two of those cases (one adult and one child) were reported in San Mateo County and fourcases were reported in Santa Clara County (one child and three adults), according to the California Department of Public Health

San Mateo County Health reported two additional cases of measles there on Wednesday. In a statement, Cassius Lockett, director of public health, policy and planning for the health department, said one of those cases was an adult resident who had recently visited Google.

"San Mateo County Health communicable disease investigators are following these cases and getting regular updates from our partners in other jurisdictions to advise those who may have been exposed to measles to consult with their local health care providers."

"The County of Santa Clara Public Health Department worked with Google to contact individuals in our county who might have come in contact with the person with measles while they may have been contagious," a Santa Clara county spokeswoman said in an email.

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