More than 80 people may have been exposed to a Texas man diagnosed with Ebola, according to the Dallas Public Health Department.
While only 12 to 18 people came into direct contact with the patient, 62 - 68 may have crossed paths with the secondary few.
The group is being monitored and the 80 are yet to show any symptoms of the disease, which is unlikely to pose a threat in countries with well-developed healthcare systems.
In a separate statement, the Texas Department of State Health Services said it had identified 100 persons who had potentially had contact with the patient.
The department was quick to emphasise that the measures were precautionary at this stage:
Out of an abundance of caution, we're starting with this very wide net, including people who have had even brief encounters with the patient or the patient's home.