BERKELEY (CBS SF) — A person with a possible case of measles was at two Berkeley library branches last week and could have exposed library patrons to the highly contagious disease, city health officials said Friday.

The person, a Contra Costa County resident, who had not yet developed the tell-tale rash associated with measles and whose diagnosis has not yet been confirmed, visited the City of Berkeley West Branch Library last Friday and Saturday and the Central Branch Library on Friday afternoon.

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Patrons who visited those libraries on Friday or Saturday should monitor themselves until March 21. Symptoms can develop between seven and 21 days after exposure.

The incident is the second possible measles exposure in Berkeley in recent weeks.

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On Feb. 20, patrons of La Mediterranee restaurant in Berkeley maybe have been exposed to measles when a San Mateo County resident with the disease ate there.

California is experiencing a major measles outbreak and residents are urged to make certain that they get the recommended two doses of the MMR vaccine, which provides 99 percent protection for those exposed to the measles virus. A single dose provides 95 percent protection.

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