- Tuberculosis (TB) is an airborne bacterial infection caused by Mycobacterium tuberculosis

- Immunity after primary infection or vaccination (cell mediated). - No maternally acquired immunity.

L17: Tuberculosis Flashcards by Ahmed Farag

Def of Tuberculosis

Tuberculosis (TB) is an airborne bacterial infection caused by Mycobacterium tuberculosis

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TB is a major global cause of disability & death especially in …… countries

developing

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TB morbidity and mortality rates were decreased but started to re-emerge again due to:

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Global epidemeology of TB

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National Epidemeology of TB

Egypt is ranked among the mid-level incidence countries.
TB in Egypt is considered an important public health problem.

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Suspected Case of TB

any patient with cough & expectoration more than 3 weeks associated with fever, loss of weight& night sweating

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Probable Case of TB

None

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Confirmed Case of TB

positive lab results and positive chest radiography

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CA of TB

Mycobacterium tuberculosis: highly resistant outside the body

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Reservoir of TB

Human open cases of TB (TB lesion open into a bronchus).

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IP of TB

to 10 w (from infection till +ve tuberculin test of appearance of a 1ry lesion)

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MOT of TB

Air-borne infection

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Infectivity Period of TB

As long as viable bacilli are discharged in the sputum
Risk of transmission is significantly reduced within days to 2 weeks after starting appropriate chemotherapy

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Susceptible age for TB

(Golden age: the safe period 5-15 years due to less exposure & stress)

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Susceptible sex for TB

More in males than females (ratio 3-1 to 5-1)

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Immunity in TB

Immunity after primary infection or vaccination (cell mediated).
No maternally acquired immunity.

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Dx of TB

Screening tests for detection of TB (IGRA and Tuberculin test)

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Principle of Tuberculin test

An intradermal test for delayed cell mediated
hypersensitivity caused by exposure to TB antigen
whether by infection or vaccination.

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Non-vaccinated positive child < 5 years …….

needs further investigations to exclude infection

what does a Positive tuberculin means?

❶ TB infection (recent or past)
❷ vaccination

Results of Tuberculin test

Steps of Tuberculin test

The test material (purified protein derivative) is injected of as 5 IU (one IU for children & persons likely to react strongly)

Recent conversion of a person who was previously negative is ……

suggestive of TB

Negative tubercelin test

Advantaes of **Interferon gamma release assays (IGRA)**

Disadvantages of **Interferon gamma release assays (IGRA)**

General Prevention of **TB**

(as mentioned in general preventive measures of droplet inf)

Specific Prevention of TB

- Active Vx - Chemoprophylaxis - Combined

Active Vx for **TB**

BCG

Nature of **BCG**

Live-attenuated bovine strain of mycobacterium TB

Dose of **BCG**

0.1 ml I.D, in the left upper arm

Indications of **BCG**

❶ In Egypt, it is compulsory in the first three months of life without tuberculin ❷ Older children & adult if only tuberculin negative ❸ At risk groups: health workers, military recruits, & food handlers

Indication of success of **BCG**

Indication of failure of **BCG**

If there is no scar formation, repeat vaccination after 3 months

Protective value of **BCG**

Type of immunity of **BCG**

It gives cellular immunity.

Does **BCG** give cross immunity?

yes

Chemoprophylaxis in **TB**

**INH is the drug of choice** ❶ Given to high risk groups such as contacts of cases. ❷ Effective in prevention of progression of latent to clinical infection. ## Footnote Study CI **VIP**

Combined Vx & Chemoprophylaxis in **TB**

in non-vaccinated high-risk contacts

Case Control Measures of **TB**

Isolation of TB

chest hospital or at home

TTT of **TB**

DOTS

Release of **TB**

after complete cure with 3 negative sputum smears

Criteria of **DOTS (Direct Observation Therapy with Short course chemotherapy)**

Advantages of **DOTS (Direct Observation Therapy with Short course chemotherapy)**

Disadvantages of DOTS (Direct Observation Therapy with Short course chemotherapy)

High cost

Measures for the contacts of TB