Q.Q.: How dangerous is the virus?

A.T.: Caused by a single-celled organism, coronavirus, the virus is initially transmitted from person to person by close contact. In 2007, Zaire virus was diagnosed in two patients who were dying of the flu.

The person who died at this time has been ruled out as the source of the disease, but the coronavirus was then confirmed in the U.K. by a person who had recently traveled to Saudi Arabia.

Q.Q.: Why is it spreading so rapidly?

A.T.: Because it circulates widely in animals, including ferrets, which are a potential model for human replication. It was used to cause a big outbreak in Asia in 1976.

Q.Q.: What will happen with the human strain?

A.T.: Scientists are currently struggling to find the genetic sequence of the newly found strain, including determining where it came from.

Q.Q.: Is it deadly in itself?

A.T.: It kills an average of 61 percent of the people it infects. But its capacity to cause severe illnesses combined with its viral mutation cycle makes the pathogen lethal for many years after infection.

Q.Q.: How did it come to be endemic in Britain?

A.T.: As the infections with the virus spread in Saudi Arabia in 2007, there were lab reports of the virus not mutating, hence prolonging its likelihood of spreading.

Q.Q.: What are the risks here?

A.T.: Contagious diseases must infect one or more people who are close to them, and the risk of infection is greatest when these cases are seen in close quarters. As the coronavirus is small in size, patients will often avoid detection and the chances of spreading the virus are higher than with an ordinary human flu virus. As the disease is infectious, it may have the potential to be dangerous enough to cause a major public health outbreak, so we must keep a vigilant eye out for it.