To help with these questions about the plague, CNN spoke with wellness expert Dr. Leana Wen, an emergency physician and ...

Fear not, for the CDC also states that "Plague is infamous for killing millions of people in Europe during the Middle Ages.

Pneumonic plague is the most deadly and easiest to spread, with a nearly 100% fatality rate untreated, said Lisa Morici, a microbiologist and immunologist at the Tulane University School of Medicine.

Pneumonic plague infected the lungs after inhaling aerosolized bacteria and septicaemic is when the bacteria infects the blood through direct exposure or via lungs or lymphatic system.

Pneumonic plague is the most deadly and easiest to spread, with a nearly 100% fatality rate untreated, said Lisa Morici, a microbiologist and immunologist at the Tulane University School of Medicine.

Pneumonic plague is the most deadly and easiest to spread, with a nearly 100% fatality rate untreated, said Lisa Morici, a microbiologist and immunologist at the Tulane University School of Medicine.

Pneumonic plague is the most deadly and easiest to spread, with a nearly 100% fatality rate untreated, said Lisa Morici, a microbiologist and immunologist at the Tulane University School of Medicine.