Tuberculosis Flashcards
How many people gets infected with TB each year?
100 000 000
How many new TB cases is there?
8 800 000 new cases of TB (140/100 000)
How many of the new cases of TB are smear positive?
4 000 000
How many people die from TB?
1 700 000 peopl (100 000 children) die from TB
- 200 people/hour die with TB
How many children are orphans as a result of paerental deaths caused by TB?
9 mln
LTI =
Latent TB Infection
What is Latent TB Infection (LTI)?
- Subclinical infection without clinical, bacteriological or radiological signs or symptoms of disease.
- Positive TST
What is Tuberculosis?
Clinically, bacteriologically and/or radiographically confirmed disease
What is chemoprophylaxis used for?
Chemoprophylaxis: treatment of infection with M. Tuberculosis to prevent progression to active TB
What is preventive chemotherapy?
Preventive chemotherapy: treatment of individuals at risk of aquiring TB who are not infected
Etiology - Mycobacterium tuberculosis complex:
- Mycobacterium africanum
- Mycobacterium bovis
- Mycobacterium EAI ( East African-Indian)
- Beijing
- Haarlem
- LAM (Latin-American and Mediterranea)
- CAS (Central and Middle Eastern Asia)
- European X family
- European T family
Transmission of TB:
- Airborne
- Ingestion of unpasteurized milk (M. Bovis)
- Inborne
Pathogenesis of TB
- clearance of the organism
- rapid progressive disease (primary disease)
- active disease many years after the infection
- chronic or latent infection
Risk factors of TB INFECTION:
- household contact
- profession-due contact
- alcoholics, drug addicts, homeless people
- immigrants from high prevalence countries
Risk factors for developing TB DISEASE:
- immunosupression (iatrogenic, HIV)
- malnutrition
- age <5yrs
- neoplastic disease
- chronic disease: DM, chronic kidney failure
- stomach resection
What are the clinical features of primary infection:
- local inflammation with granuloma formation
- lymphadenopathy (hilar, mediastinal)
- lobar collapse due to bronchial compression (may lead to bronchestasis)
- pleural effusion (lymphocytic exudate with high protein but low glucose concentration)
- erythema nodosum
- in children manifestation may be scarce and non-specific
What are the clinical features in latent infection:
- no clinical features
- immunological record:
- tuberculin skin test
- interferon gamma release test
Post primary tuberculosis:
- direct progression of primary infection
- hematogenous spread
- reactivation pf primary disease
- exogenous reinfection
What is the pulmonary symptoms of post-primary tuberculosis?
- cough
- sputum
- hemoptysis
- chest pain
- dyspnoea
What are the general symptoms of post-primary tuberculosis?
- fever
- night sweats
- weight loss
What are the clinical signs of pulmonary TB?
- reduced breath sounds and consolidation
- wheezing in bronchial narrowing
- signs of extrapulmonary involvment
What is so special about TB in children?
- higher risk of severe primary progressive disease after infection
- higher proportion of disseminated and extrapulmonary disease
- unreliable symptoms and signs
- bacteriological examination difficult
3-8 weeks after primary infection of TB in children:
- TST response
- erythema nodosum
1-3 months after primary infection of TB in children:
- hematogenous spread (meningitis and miliary in infants)
3-7 months after primary infection of TB in children:
- bronchial disease(<5 years)
- pleural effusion (>5 years)
1-3 years after primary infection of TB in children:
- osteo-articular disease
- calcification
- adult-type disease
What is special about patients with HIV and TB?
- higher frequency of extrapulmonary TB
- higher frequency of atypical localisation
- greater frequency of general symptoms
- shorter duration of symptoms before diagnosis
Diagnostic materials:
- gastric aspirate
- bronchial washings
- cerebrospinal fluid
- pleural fluid
- urine
- sputum (more useful in adults)
- other body fluids
Diagnostic tests:
- AFB smears
- Culture: solid media up to 10 weeks, liquid media up to 6 weeks
- PCR
What is the gold standard to confirm tuberculosis?
Culture
TST =
Tuberculin Skin Test
The tuberculin skin test (TST):
Can not differentiate between latent and active disease.
Tool available for diagnosis of TB infection
IGRA =
Interferon Gamma Release Assay
Interferon gamma release assay (IGRA):
Cell mediated immunity - circulating lymphocytes are extracted from the venous blood nad exposed to antigens of M. Tuberculosis and after 6-24hrs the production of interferon gamma ins measured
Serology-
Blood tests to measure the humoral response to M. tuberculosis
What does the interpetation of TST depend on?
- diameter of the induration
- person’s risk of being infected with TB and risk of progression to disease if infected
Diameter of induration of _> 5mm is considered positive in:
- HIV-infected children
- severly malnourished childreen (with clinical evidence of marasmus or kwashiorkor)
Diameter of induration of _> 10mm is considered positive in:
- all other children (whether or not they have recieved BCG vaccination)
Positive TST:
- active TB disease
- latent TB infection
- recent exposure to M. tuberculosis
- exposure to enviromental mycobacteria
- BCG-vaccination
Causes of false positive TST results:
- incorrect interpetation of test
- BCG vaccine
- infection with nontuberculous mycobacteria
IGRA pros and cons:
- good tool in diagnostics of latent TB
- unlike TST, IGRA is negative in healthy vaccinated individuals
- may be false negative in active TB
- not enough experience in hcildren <5 years
Basic principles of treatment:
- combination of antibiotoics
- rapid killing of mycobacteria
• interrruption of the chain transmission
- rapid killing of mycobacteria
- long duration of treatment
- sterilization of lesions
• prevention of relapse
- sterilization of lesions
First line TB drugs:
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
- Streptomycin
Rational treatment standard:
- intensive phase (2 months)
• rapid killing - continuation phase (4-6 months)
• sterilization
DOT =
Direct Observed Therapy
Direct Observed Therapy (DOT):
Recommended by WHO for all cases, at least in the intesive phase
DOTS =
Directly Observed Therapy Short-Course
What is the BCG vaccine?
BCG vaccine is a live vaccine prepared from attenuated strains of M. bovis
What is the BCG vaccine used to for?
BCG vaccine is used to prevent disseminated and other life-threatening infections of M. tuberculosis in infants and young children.
- is used in more than 100 countries
NOT DONE SLIDE 41 and 18
Meh
