Why did everyone Edgar Allan Poe loved die of tuberculosis?

Many of the most important people in Poe's life died of tuberculosis. You can see how it affected him in works like "The Raven." When he was writing it, his wife was in the next room coughing up blood. He knew he would soon be in the same situation as the narrator of "The Raven." He also wrote "The Mask of Red Death," which is about a plague that you can't hide from that makes you cough of blood and die even if you barricade yourself in a fortress and allow no one in. So yeah, it affected him pretty deeply.