WHAT IS TUBERCULOSIS (TB):
- TB is a deadly infectious disease
- Airborne bacterial infection caused by :
Mycobacterium Tuberculosis
- Mainly affects lungs but can affect other organs or tissues
- Transmitted when infected person coughs or sneezes bacteria
o Spreads through air to be breathed in by others
o However, TB requires prolonged exposure to be
infected
o Once inhaled bacterium lodges into lung tissues
-
EPIDEMIOLOGY OF TUBERCULOSIS (TB):
¼ of world population are infected with TB but most have latent
10 million people have active TB
CLINICAL TERMS OF TB:
ACTIVE = Symptomatic Disease
Bacteria is multiplying and attacking lungs &/ or other parts of body
TB starts in lung but can move through blood and lymphatic system to other parts
LATENT = Asymptomatic disease
Bacteria in body but no symptoms
Disease may not become active unless individual immunocompromised
May take months years for disease to become active
- Lifetime risk of active TB in otherwise healthy people is 10%
- Risk of active TB in those with HIV is 10% per year
Effective control of TB depends upon
- prevention of open cases
- rapid initiation of treatment when cases do occur preferably before they become open
Open disease – Means “Acid fast bacilli” (AFB) seen on sputum microscopy
Closed disease – Means any organ other than lung or respiratory tract affected
WHO IS AT RISK OF TB INFECTION?
- Family and Friends of infected person
- High incidence rate in countries like Asia & Africa
- Homeless, Injection drug users & HIV
, WHO IS AT RISK OF ACTIVE TB?
- Babies and young children - Organ transplant recipients
- Chronic conditions: Diabetes/ Kidney - Cancer patients undergoing chemo
Disease - Autoimmune conditions
- HIV/ AIDs
HOW CAN TB BE PREVENTED BY VACCINATION?
Vaccination: Bacillus Calmette - Guerin BCG Vaccine
- Live attenuated vaccine : Mycobacterium Bovis
- Offers 60 – 80% protection against severe disease
- Protection lasts at least 15 years and may be upto 60 years
-
Offered to all adolescents in UK until 2005
Now given on a risk based program for:
- If they come from high incidence countries
- If occupational risk: health and vet staff in contact with infected patient or sample
- Recommended for people with weakened immune system where they take:
o Long term steroid medicine o Biological inhibitors: TNF
o Chemotherapy Inhibitors
PREVENTION OF LATENT TB:
Chemoprophylaxis:
Drug treatment Reduces risk of development into Active TB
Contact Tracing and testing
DIAGNOSIS OF LATENT TB:
Mantoux Skin Test:
- Injecting purified protein component of M Tuberculosis bacterium under forearm skin
- Measure size of skin reaction
- Cross reactions may give false positives
Interferon gamma release assay (T-spot or Quantiferon) – new method:
- WBCs release interferon gamma when presented with antigens specific to M. tuberculosis
- More specific than skin testing, less risk of non-response in severe immunosuppression
- Carried out in labs within specific time
- TB is a deadly infectious disease
- Airborne bacterial infection caused by :
Mycobacterium Tuberculosis
- Mainly affects lungs but can affect other organs or tissues
- Transmitted when infected person coughs or sneezes bacteria
o Spreads through air to be breathed in by others
o However, TB requires prolonged exposure to be
infected
o Once inhaled bacterium lodges into lung tissues
-
EPIDEMIOLOGY OF TUBERCULOSIS (TB):
¼ of world population are infected with TB but most have latent
10 million people have active TB
CLINICAL TERMS OF TB:
ACTIVE = Symptomatic Disease
Bacteria is multiplying and attacking lungs &/ or other parts of body
TB starts in lung but can move through blood and lymphatic system to other parts
LATENT = Asymptomatic disease
Bacteria in body but no symptoms
Disease may not become active unless individual immunocompromised
May take months years for disease to become active
- Lifetime risk of active TB in otherwise healthy people is 10%
- Risk of active TB in those with HIV is 10% per year
Effective control of TB depends upon
- prevention of open cases
- rapid initiation of treatment when cases do occur preferably before they become open
Open disease – Means “Acid fast bacilli” (AFB) seen on sputum microscopy
Closed disease – Means any organ other than lung or respiratory tract affected
WHO IS AT RISK OF TB INFECTION?
- Family and Friends of infected person
- High incidence rate in countries like Asia & Africa
- Homeless, Injection drug users & HIV
, WHO IS AT RISK OF ACTIVE TB?
- Babies and young children - Organ transplant recipients
- Chronic conditions: Diabetes/ Kidney - Cancer patients undergoing chemo
Disease - Autoimmune conditions
- HIV/ AIDs
HOW CAN TB BE PREVENTED BY VACCINATION?
Vaccination: Bacillus Calmette - Guerin BCG Vaccine
- Live attenuated vaccine : Mycobacterium Bovis
- Offers 60 – 80% protection against severe disease
- Protection lasts at least 15 years and may be upto 60 years
-
Offered to all adolescents in UK until 2005
Now given on a risk based program for:
- If they come from high incidence countries
- If occupational risk: health and vet staff in contact with infected patient or sample
- Recommended for people with weakened immune system where they take:
o Long term steroid medicine o Biological inhibitors: TNF
o Chemotherapy Inhibitors
PREVENTION OF LATENT TB:
Chemoprophylaxis:
Drug treatment Reduces risk of development into Active TB
Contact Tracing and testing
DIAGNOSIS OF LATENT TB:
Mantoux Skin Test:
- Injecting purified protein component of M Tuberculosis bacterium under forearm skin
- Measure size of skin reaction
- Cross reactions may give false positives
Interferon gamma release assay (T-spot or Quantiferon) – new method:
- WBCs release interferon gamma when presented with antigens specific to M. tuberculosis
- More specific than skin testing, less risk of non-response in severe immunosuppression
- Carried out in labs within specific time
