The deadliest disease in the world is tuberculosis as well as the Bubonic plague.
Tuberculosis has claimed at least 1 billion lives since it's been around.
Tuberculosis is a serious and contagious bacterial infection, that is often caused by Mycobacterium tuberculosis, which primarily attacks your lungs, although it can also affect other organs like your spine or kidneys, and spread through airborne droplets when a person infected with tuberculosis sneezes or coughs.
There are also two types of tuberculosis which include latent or inactive TB, in which the germs live in the body without symptoms and active TB disease, which makes you sick with symptoms like chronic cough, sometimes with blood, fever, night sweats and weight loss, and it requires long term antibiotics for treatment.
The bubonic plague is also another deadliest disease that killed around 75 million to 200 million people in North Africa and Eurasia, between the years of 1346 and 1353 and wiped out about a third of the population of Europe.
The bubonic plague also devastated parts of Asia and the Middle East.
The initial outbreak of the bubonic plague was catastrophic, but the plague also recurred although it recurred less severely and still even now remains an endemic in some areas today, although there's less cases of the bubonic plague reported annually.
The bubonic plague is a severe bacterial infection also known as Yersinia Pestis and is spread by infected flea bites, causing swollen and painful lymph nodes, also known as buboes, as well as fever chills as well as headache, with a high fatality rate, although it's treatable with antibiotics like ciprofloxacin or even doxycycline.
The bubonic plague is the most common form of plague, and is famously linked to the medieval black death still occurs today, but mainly from rodent fleas in rural areas.
The Spanish Flu is also another deadliest disease or condition, and killed around 25 million to 50 million people.
The 1918–1920 flu pandemic, which is also known as the Great Influenza epidemic or by the common misnomer Spanish flu, was an exceptionally deadly global influenza pandemic caused by the H1N1 subtype of the influenza A virus.
The Spanish flu started in 1918 and ended in 1920.
The Spanish Flu was caused by a highly virulent H1N1 influenza A virus, and is believed to have originated from an avian (bird) source, which mutated to infect humans and spread globally due to troop movements during World War I.
The Spanish Flu's devastating impact came from its unique genetic combination, causing severe lung inflammation (pneumonia) and overwhelming healthy young adults, often leading to secondary bacterial infections.