SEOUL, South Korea — Fears of the deadly virus that causes Middle East respiratory syndrome enveloped South Korea on Wednesday as the authorities nearly doubled the number of quarantined people they say may have been exposed, temporarily closed more than 700 kindergartens and schools and refused to identify the six hospitals where infections had been confirmed.

The net result of the government response in South Korea, where the outbreak has suddenly become the largest outside the Middle East, was not only to frighten people but also to discourage many of them from visiting any hospitals — perhaps increasing the possibility that undiscovered and untreated patients could spread the disease even further.

Amplifying the anxiety, as well, was a deep skepticism of the government’s handling of emergencies, caused in part by the mismanagement of the ferry disaster last year that killed 304 people, mostly high school students.

“A lot of fear we see now is rooted in the distrust of the government and what it says,” said Yu Min-yeong, head of Acase, a crisis management consulting firm based in Seoul.