Comm Dis -Pulmonary Tuberculosis Flashcards
What is the Epidemiology of TB in South Africa?
Low socio economic status
High HIV Co infection burden
Delayed health seeking behaviour among individuals with TB
High burden of undiagTB in communities
What are the causes of TB?
Mycobacterium Tuberculosis humanus and bovis
What are the modes of transmission for TB?
Droplet infection where the Tuberculosis can be coughed up into the air from lungs and then could be inhaled
It could be inhaled through dust as the TB bacilli can live up to 6 months after being coughed up
Drinking unpasturized milk of an infected cow
Inoculation babies could get infected during birth by contaminated hospital equipment
How can a baby be born with TB?
If the mother suffers from miliary TB and the placental focus or leison ruptures and infects fetal circulation
What are the factors affecting the cell mediated immunity of an infected person?
Malnutrition and undernourishment
Age -A very young person whose immune system is not yet developed yet and the elderly who have had their immune responses weakened
Diabetes Mellitis
Emotional as well as physical exhaustion and stress
Virus infections such as flu or measles
Alcoholism
Why does the disease occur more in people who got the BCG vaccine?
The vaccine weakens people’s immune system so they cannot elicit sufficient cell mediated immune reaction anymore and therefore susceptible to TB and M.Tuberculosis undergoes a mutation and a new strain developed which is resistant to the vaccine and if a person is affected by the new strain they could become ill
What is the pathogenesis of TB?
When M.Tuberculosis invades the body it is phagocytised by macrophages and the TB antigen is processed
Tissue hypersensitivity and cell mediated immunity develop 6 to 14 weeks after invasion M TB can proliferate after invasion in the primary focus as well as the metastatic foci
What does the natural endogenic cycle of TB?
Formation of tubercles
Ceasation,fibrosis and calcification
Recovery process
How do tubercles form?
A nodule will form which consist of lymphocytes,fibroblasts and capillary macrophages and the macrophages secrete fibroblasts and stimulate substances which deposit Collagen to fibrosis of the tubercle and this hard tubercle is the bodies tissue reaction in process of isolation of the infection
What is the caseation,fibrosis and calcification?
Action of macrophages causes tissue necrosis to form of the tubercle and it changes to a solid or semi solid caseous mass (cold abscess) and o2 tension don’t cause the growth of M TB so active connective tissue formation takes place around the mass and the connective tissue replaces necrotic tissue and the deposit of calcium in the mass is the beginning of a tubercle leison
What is the the recovery process?
Takes place 8 to 10 weeks after invasion owing to a cell mediated immunity has taken place and complete sterilization of all leisons
What are the systemic manifestations of TB?
Loss of appetite
Anemia
Pyrexia
Severe night sweats
Tachycardia
What are the local manifestations of TB?
Coughing,sputum,heamptysis and dyspnia
Pleural pain
Hoarseness of larynx
Diarrhea
Headache as a result of meninges
How to establish the degree of cell mediated immunity?
By the tuberculin test
