Tuberculosis

Question 1

Earliest evidence

Answer 1

Neolithic

Question 2

Spread

Answer 2

Droplet infection

Question 3

Tuberculosis on the skeleton

Answer 3

• Distinctive skeletal changes associated with TB
• Destructive lesions
• Commonly vertebrae
• Possibly cranium, ribs, major joints
• only occur in 1-5% of skeletal changes

Question 4

Muller et al 2014 - Study aims

Answer 4

Apply rigorous analytical regime for detection of MTBC

Question 5

Muller et al 2014 - Sample size

Answer 5

• 19 individuals with skeletal changes suggestive of TB sampled
• 14 individuals with no skeletal changes sampled
• Majority taken from ribs or non pathological long bones
• Only a few from pathological vertebrae
• Hacksaw or electronic drill used

Question 6

Muller et al 2014 - aDNA analysis process

Answer 6

• Carried out in 2 labs
• All surfaces periodically steralised by UV radiation and cleaned
• All DNA extractions accompanied by 2 blanks per 5-7 samples
• To remove external contamination some of the outer surgaces were removed
• At least 2 DNA extractions performed per sample

Question 7

Muller et al 2014 - Results

Answer 7

• Identified 12 samples that gave definite evidence for the presence of MTBC DNA
• 22 classified as possible
• None of the definite samples came from vertebrae displaying lesions
• 9 of the 12 came from skeletal elements displaying lesions considered nonspecific for TB
• 3 showed widespread new bone formation
• 2 of the definite result were from unaffected parts of the skeleton

Question 8

Application of Muller study to wider TB study

Answer 8

• Emphasised that evidence of MTBC aDNA doesn’t confirm that the lesions displayed by an individual are actually caused by TB
• Failure to produce MTBC doesn’t exclude individuals from having suffured TB

Question 9

Pulmonary TB

Answer 9

• More common
• May result from extrapulmonary infections
• Spread through bloodstream

Question 10

Gastrointestinal TB

Answer 10

• Spread of bovine forms to humans
• Consumption of infected meat and milk
• intestinal pathway
• more common in children

Question 11

Primary vs secondary TB

Answer 11

• Primary is spread through venous and lymphatic systems
• Forms calcified lesions, no skeletal involvement
• Secondary is repressed immune system
• Skeleton affected in 3-5% of all cases
• Aggressive immune response destroys normal tissue

Question 12

Salo et al 1994 - overview

Answer 12

• MBTC found in a lung lesion of a spontaneously mummified, 1000 year old adult female body in Southern Peru
• Most specific evidence possible for pre-Columbian presence of human tuberculosis in the New World