Signs And Symptoms Of Tuberculosis

Signs And Symptoms Of Tuberculosis

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Tuberculosis is a granulomatous infection in humans: Tuberculosis is caused by Mycobacterium tuberculosis in lungs and other tissues of human body.

Symptoms of tuberculosis

Spread of Tuberculosis

• Local spread: Macrophages cause it by carrying bacilli in surrounding tissues.
• Lymphatic spread: Tuberculosis is primarily an infection of lymphoid tissues. Bacilli may pass into lymphoid follicles of the pharynx, bronchi, intestines or regional lymph nodes leading to regional tuberculous lymphadenitis which is typical of childhood infections. The primary complex is the primary focus with lymphangitis and lymphadenitis.
• Hematogenous spread: It occurs either as a result of tuberculous bacteremia due to drainage of lymphatics into the venous system or because of caseous material escaping via an ulcerated wall of vein. This produces millet seed-sized lesions in diffrent organs of the body like lungs, liver, kidneys, bones and other tissues and is known as miliary tuberculosis.

Signs of pulmonary TB

• By natural passages: Infection can spread from:
  • Lung lesions into pleura (tuberculous pleurisy)
  • Transbronchial spread into the adjacent lung segments
  • Tuberculous salpingitis into the peritoneal cavity (tuberculous peritonitis)
  • Infected sputum into the larynx (tuberculous laryngitis)
  • Swallowingofinfectedsputum(ileocaecal tuberculosis)
  • Renal lesions into the ureter and down to the trigone of the bladder.

Types of Tuberculosis

Depending on type of tissue response and age, infection of tubercle bacilli is of two types:

• Primary tuberculosis
• Secondary tuberculosis

Primary Tuberculosis

• Infection of an individual who was not previously infected or immunized is known as primary tuberculosis or Ghon’s complex or childhood tuberculosis.
• The primary complex is the lesion that is produced inside the tissue of the portal of entry with foci in the draining lymphatic vessels and lymph nodes.
• Most commonly involved tissues for the primary complex are the lungs and hilar lymph nodes. Other tissues which may show primary complexity are tonsils and cervical lymph nodes, and in the case of ingested bacilli, the lesions may be found in the small intestine and mesenteric lymph nodes.
• Incidence of the disseminated form of progressive primary.
• Tuberculosis is particularly high in immunocompromised host, For Example. in patients of AIDS.
• Primary tuberculosis in the lungs have three components:
  • Pulmonary component: The lesion inside the lung is the primary focus or Ghon’s focus. It is usually a 1-2 cm solitary area of tuberculous pneumonia which is located peripherally under a patch of pleurisy, in any part of the lung but more often in subpleural focus in upper part of the lower lobe.
  • Lymphatic vessel component: Lymphatics draining the lung lesion consists of phagocytes which contain bacilli and may develop beaded, miliary tubercles along the path of hilar lymph nodes.
  • Lymph node component: This consists of enlarged hilar and tracheobronchial lymph nodes in the area drained. The affected lymph nodes are matted and show caseation necrosis. Nodal lesions are a potential source of reinfection later.

Secondary Tuberculosis

It is the infection of an individual who has been previously infected or sensitized and is known as secondary or postprimary reinfection, or chronic tuberculosis. Infection may occur from:

• Endogenous source such as reactivation of dormant primary complex
• Exogenous source such as fresh dose of reinfection by tubercle bacilli.

Secondary tuberculosis occurs most commonly in lungs. Other sites and tissues which can be involved are lymph nodes, tonsils, pharynx, larynx, small intestine and skin.

Diagnosis of Tuberculosis

Diagnosis is made by the following tests:

• AFB microscopy of diagnostic specimens such as sputum, and aspirated material.
• Mycobacterial culture: Traditional method on LJ medium for 4-8 weeks, the newer rapid method by HPLC of mycolic acid with result in 2-3 weeks.
• Molecular methods such as PCR.
• Complete hemogram: Presence of lymphocytosis and raised ESR.
• Radiographic procedures, For Example. chest X-ray showing characteristic hilar nodules and other parenchymal changes.
• Mantoux skin test.
• Serologic tests based on the detection of antibodies are not useful although these are being advocated in some developing countries.
• Fine needle aspiration cytology of an enlarged peripheral lymph node is a quite useful and easy way for confirmation of diagnosis and has largely replaced the biopsy diagnosis of tuberculosis.