Oldest contagious disease

The oldest contagious disease known to affect humans is tuberculosis, a respiratory disease caused by Mycobacterium tuberculosis. The bacterium is thought to have existed in something similar to its modern form for more than 70,000 years, and has been infecting humans since early prehistory. In 2007, a group of scientists published a paper that reported signs of tuberculosis infection in a 500,000-year-old homo erectus skeleton.

Tuberculosis (TB) is a bacterial infection that is spread to others through the coughing or sneezing of an infected person. Symptoms include a persistent cough, high temperature, fatigue, and swellings in the neck.

Egyptian mummies from 2400 BC show signs of tuberculosis, and written evidence from India that describes tuberculosis, survives from 3300 years ago.

In ancient Greece, tuberculosis was known as Phtisis and was described by Greek physician Hippocrates as particularly fatal to young adults. The Greek physician Clarissimus Galen, who treated the Roman Emperor Marcus Aurelius in 174 AD, wrote about tuberculosis and recommended fresh air, milk, and sea voyages as effective treatments.

Tuberculosis' rival for this record is another illness that has haunted humanity since prehistory -- leprosy. Some researchers believe this disease may actually be older.