But the third challenge we have — and probably even bigger one, the biggest challenge — is that, in contrast to smallpox where you could always see your enemy — every single person almost who was infected with smallpox had this telltale rash.
El tercer reto que tenemos (y quizá el mayor de ellos) es que, a diferencia la viruela, con la que siempre se veía al enemigo, ya que casi todas las personas infectadas presentaban estas erupciones tan reveladoras.