Short answers, pulled from the story.
The Black Death began in the year 1347 and killed an estimated 25 million people in just five years. This catastrophe reduced the old world population from 450 million to between 350 and 375 million.
Microscopic pathogens include bacteria like Mycobacterium tuberculosis and Staphylococcus aureus, viruses such as HIV and Severe acute respiratory syndrome coronavirus 2, fungi like Candida and Aspergillus, and parasites such as Plasmodium. Prions like the one causing Creutzfeldt, Jakob disease are also infectious agents that kill every animal and person they infect.
Mary Mallon, known as Typhoid Mary, was an asymptomatic carrier of typhoid fever who infected 53 people over the course of her career as a cook. Three of those 53 people died from the infection despite Mary Mallon never showing symptoms herself.
The Influenza Pandemic of 1918 killed 25 to 50 million people, which is approximately 2% of the world population at the time. The Black Death killed an estimated 25 million people in just five years starting in 1347.
Certain genetic variants near the IL28B gene influence the clearance of hepatitis C, and mutations in the ERAP2 gene affect survival rates during the plague. Genetic factors play a crucial role in susceptibility, with some variants making individuals more susceptible to life-threatening diseases.
COVID-19 directly caused 8.7 million deaths in 2021 alone. This pandemic emerged in the 21st century as a major global health crisis following historical pandemics like the Plague of Justinian and the Black Death.