A new report counts hundreds of times that U.S. doctors and hospitals raised false alarms about possible Ebola cases, finding that fewer than one in five warranted more investigation.

The Centers for Disease Control and Prevention report looked at Ebola-related calls the agency received this year from doctors, hospitals, and state and local health departments. In most calls, the patient had neither traveled to an Ebola-affected country nor had contact with an Ebola patient.

Of 650 patients flagged to federal officials, four ended up testing positive.

Only 18 percent of the flagged patients had signs or symptoms consistent with Ebola or some risk factor that warranted additional investigation, the report found.

In some cases, doctors leaped straight to Ebola as a possible diagnosis and initially did not test for malaria or other illnesses that might explain certain symptoms.

The calls peaked in October, after the first-ever diagnosis of an Ebola case in the United States - a Liberian man who grew sick after traveling to Dallas and died there. Two Dallas nurses who cared for him caught the illness. They recovered, but the case spurred a wave of fear. - AP