When a new, unknown disease breaks out

On February 28, 2003, the local office of the World Health Organization in Hanoi, Vietnam, received a call from a small private hospital with a capacity of no more than 60 beds. Two days before, its staff admitted a patient showing symptoms of atypical flu. To rule out a potential case of bird flu they requested the help of WHOs experts to try and determine what the disease really was.

Their call was answered by Carlo Urbani, an Italian-born contagious disease specialist and Doctors Without...