Tuberculosis: The world's most infectious disease to a human.
In 2008, archaeologists uncovered two 9,000-year-old skeletons. There is no definitive way of knowing what killed these ancient people, but their bones were infected by an all too familiar bacterium.
TB called mycobacterial tuberculosis, are airborne, they travel into our airways and infect our lungs. Immune cells called macrophages rush to the infection site, attempting to absorb and break down the bacterial invaders.
In many cases, this response is enough to remove the bacteria. But in the individual with other medical conditions ranging from malnutrition and HIV to diabetes and pregnancy. If so, mycobacterium TB will reproduce inside those macrophages, and form colonies in the surrounding lung tissue.
They infect more cells, the bacterias employ cell-degrading enzymes that destroy the infected tissue, triggering chest pain, and causing patients to cough up blood. The damage to the lungs leads to oxygen deprivation. This begins a flood of hormonal changes including decreases in appetite and iron production.
Microbes can spread by the skeletal system, it causes back pain and difficulty moving to the kidneys and intestines, causing abdominal pain. The brain causing impaired consciousness and even headache. These symptoms produce bloody cough, weight loss, hacking, and ashen skin.