NBC News has learned that since last week, there have been at least 22 inquiries about suspected Ebola cases in the United States — a sign of the high alert in U.S. hospitals and around the country amid worries about Ebola in West Africa. None of the cases was confirmed.

Of the 22 suspected cases reported to government health officials, only four met the requirements for testing, and negative results are in for three of them — two of the patients had malaria and one had influenza. Results had not arrived for the fourth.

On Monday, Mount Sinai hospital in New York said it had placed a patient who had traveled to West Africa in isolation. Last week, an Emergency Room in the Charlotte area was briefly closed because of an Ebola scare.

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-Stacey Naggiar