Tuberculosis

Question 1

Definition

Answer 1

A group of disorders due to infection by mycobacteria species characterised by chronic inflammation and manifest clinically in most systems of the body.

Tuberculosis is a chronic granulomatous infectious disease caused by Mycobacterium tuberculosis complex, primarily affecting the lungs but capable of involving any organ system.

Question 2

Epidemiology

Answer 2

Affects about 30% of the world’s population
8-10 million people develop the disease annually
1 million (10%) occur in children under 15 years
About 3 million people die from TB annually including 250,000 children
Developing countries bear the greatest burden
95% of cases in children under 12 years of age are smear-negative
Poses a problem when only smear-positive TB cases are reported.
This leads to underestimation of the burden of TB in children.

Question 3

REASONS FOR TB RESURGENCE

Answer 3

1. Worsening economic situations
2. Multidrug resistance
3. HIV pandemic
4. Large number of displaced persons living in poor conditions as a result of conflicts and wars

Question 4

AETIOLOGY

Answer 4

1. Mycobacterium tuberculosis
2. Mycobacterium bovis
3. Mycobacterium africanus
4. Mycobacterium microti
5. MAC (avian complex) more in immunocompromised

Question 5

CHARACTERISTICS OF MYCOBACTERIA

Answer 5

They are gram-resistant, non-motile pleomorphic rods.
Have peculiar cell wall which contains peptidoglycan and complex lipids which resist decolouration by acids and alcohol hence classified as acids-fast bacilli
The cell wall resists destruction by many antimicrobial drugs, acids and alkali
They multiply slowly
They remain viable in macrophages by resisting macrophage-killing

Question 6

Transmission

Answer 6

Source of infections
-The most important source is the sputum of persons with open tuberculosis

Mode of spread
- inhalation,
ingestion,
skin and mucous membrane penetration

Question 7

Risk factors

Answer 7

Household contacts of newly diagnosed smear-positive cases

Overcrowded and poor living conditions

Very young age < 5 years & adolescents

Severe malnutrition

Children with recent measles, pertussis & HIV infection