Keep Calm

It was simply a matter of time and the game of numbers. The CDC has announced that a man who took a commercial flight from Liberia that landed in Dallas on Sept. 20 has been found to have the Ebola virus. He is the first traveler to have brought the virus to the United States on a passenger plane and the first in whom Ebola has been diagnosed outside of Africa.

The man, who was visiting relatives in the United States, was not ill during the flight, health officials said at a news conference Tuesday evening. Indeed, he was screened before he boarded the flight and had no fever. Because Ebola is not contagious until symptoms develop, there is “zero chance” that the patient infected anyone else on the flight.

Take a deep breath – before you panic – remember – Ebola is spread only by direct contact with body fluids from someone who is ill.

A team from the C.D.C. is being dispatched to Dallas to help trace any contacts who may have been infected, including family members, health care workers and others with whom the patient spent time in Dallas. Health officials in Texas said they had already begun that process. It is totally possible that family members who were with the man while he was ill would turn out to be infected.

Contact tracing involves identifying people who might have been exposed to the patient during the time he was infectious, and then monitoring them for symptoms every day for 21 days — the full incubation period of the disease. Most people develop symptoms within eight to 10 days of being exposed. Anyone who starts running a fever or having symptoms is then isolated and tested for Ebola. If the test is positive, that person is kept in isolation and treated, and his or her contacts are then traced for 21 days. The process is repeated until there are no new cases.