Ancient TB 3000 years older than thought

The discovery of the earliest known cases of human tuberculosis (TB) in bones found submerged off the coast of Israel shows that the disease is 3000 years older than previously thought.

A diver finds the earliest known case of TB

Direct examination of this ancient DNA confirms the latest theory that bovine TB evolved later than human TB. The new research, led by scientists from UCL and Tel-Aviv University and published today in PLoS One, sheds light on how the TB bacterium has evolved over the millennia and increases our understanding of how it may change in the future.

Dr Helen Donoghue, leader of the collaborative team, said: “What is fascinating is that the infecting organism is definitely the human strain of tuberculosis, in contrast to the original theory that human TB evolved from bovine TB after animal domestication. This gives us the best evidence yet that in a community with domesticated animals but before dairying, the infecting strain was actually the human pathogen.”

The team conducted detailed analyses of the bones that revealed DNA and cell wall lipids from Mycobacterium tuberculosis - the principal agent of human TB. The DNA was sufficiently well-preserved for molecular typing to be carried out and the analysis of the bacterial cell wall lipids by high performance liquid chromatography provided direct, confirmatory evidence of tuberculosis.

“We were also able to show that the DNA of the strain of TB in these skeletons had lost a particular piece of DNA which is characteristic of a common family of strains present in the world today. The fact that this deletion had occurred 9000 years ago gives us a much better idea of the rate of change of the bacterium over time, and indicates an extremely long association with humans,” said Dr Donoghue.