Tuberculosis Flashcards
How many people are infected with TB worldwide?
2 billion
What number is it ranked in deaths due to infectious disease worldwide?
second
How many new cases are there annually?
8.6M
Until when was TB in the UK thought to be under control?
The mid 1980s due to immigration
Why is TB a major problem in London?
Immigration from a high incidence area
What organism is responsible for causing TB?
mycobacteria
Where is mycobacteria ubiquitous?
The soil and water
What does mycobacteria bovis cause?
Bovine TB
What does mycobacteria leprae cause?
leprosy
Briefly give a description of mycobacteria
very slow growing non motile bacillus which is aerobic
very thick cell wall
What is mycobacteria resistant to?
acid, alkali, detergents, neutrophils and macrophage destruction due to being accustomed to tough soil environment
How is mycobacterium tuberculosis transmitted?
Open Tb - coughing and sneezing
Why can TB not be transmitted outside?
The mycobacteria are eliminated by UV are undergo infinite dilution
Do large or small inhaled droplets do more harm?
Small as large nuclei are cleared but small impact the alveoli and slowly proliferate
How is mycobacterium bovis transmitted?
drinking infected cows milk and deposited in cervical lymph nodes although this is rare now due to the pasteurisation of milk
Briefly describe the immunological pathway
T helper cells from the lymph nodes undergo clonal selection due to being activated by the antigen on the antigen presenting cell and migrate to the alveolus where they activate macrophages forming epitheliod cells and causing tissue damage
What does the accumulation of macrophages, epitheliod and langhans cells form?
Granulomas
What is a characteristic feature of TB
Central caseating necrosis which may later calcify
State one negative and one positive of the Th1 mediated immunological response
eliminates and reduces number of mycobacteria
Tissue destruction
Name the 2 factors that influence the outcome of infection
Infection
Susceptibility
Name the 2 factors of infection
virulence
number
Name the 5 components of susceptibility
Age immunosuppression Nutrition race genetics
What is primary infection?
No preceding exposure or immunity
Who is usually affected by primary infection?
children
