The Ebola outbreak in West Africa has prompted hospitals and health authorities in other countries to take precautions that often go beyond experts' recommendations, showing the impact of public concern about the deadly disease.

Health officials in Charlotte, N.C., are taking no chances with three missionaries who returned to the U.S. earlier this week from Liberia. All had contact with patients sick with Ebola. So even though they are healthy, the three have been quarantined on the campus of the religious organization for which they work.

Quarantining people who were exposed to Ebola but don't have symptoms is unusual. But their employer and the public health department say they want to go the extra mile. "We want to be overly cautious," said Stephen Keener, medical director of the Mecklenburg County Health Department, which issued a quarantine order for the missionaries.

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The measure was taken "so the public can be reassured of how we're handling this," said Bruce Johnson, president of SIM USA, the organization for which the missionaries work. The three—two doctors and the husband of one of the infected Americans evacuated earlier to the U.S.—have been quarantined for 21 days from their most recent exposure, the maximum incubation period for the virus.