Since it first broke out, Ebola has killed nearly 2,500 people in West Africa, and the three hardest hit countries, Sierra Leone, Liberia and Guinea, have struggled to stop it. Tuesday, President Obama outlined a major response, saying he will deploy 3,000 U.S. troops and medical personnel to the besieged countries in an effort to help contain the virus from spreading further.

Many Boston-area medical centers are already involved in relief efforts, including Massachusetts General Hospital. 

Dr. Stephen Calderwood is the chief of MGH’s division of infectious diseases and has consulted with colleagues who’ve just returned from Africa.