Tuberculosis

Tuberculosis is a communicable chronic granulomatous disease caused by Mycobacterium tuberculosis , where the center of the granuloma is Caseous necrosis It usually involves the lungs but may affect any organ or tissue in the body

Among medically and economically deprived persons throughout the world, tuberculosis remains a leading cause of death. It is the most common cause of death from a single infectious agent. It is estimated that 1.7 billion people are infected worldwide, with 8 to 10 million new cases and 3 million deaths per year.

since 1985 , In Western World , Death from TB increased because of increase incidence of Tuberculosis in HIV- infected persons.

Tb risk factors :- AIDS , Immunosuppression Drug resistance Alcoholism Malnutrition Chronic renal failure Chronic lung disease Hodgkin lymphoma Diabetes mellitus

Most , perhaps all, of these predisposing risk factors are related to a decrease in the capacity to develop and maintain T cell-mediated immunity against the infectious agent

Transmission Although other routes may be involved , but most infections are acquired by Respiratory Transmission by : Coughing Sneezing or any other way that will expel bacilli into the air

Optimal conditions for transmission include: overcrowding poor personal hygiene poor public hygiene Poor nutrition

Mycobacteria are slender rods that are acid-fast Etiology Mycobacteria are slender rods that are acid-fast M. tuberculosis hominis is responsible for most cases of tuberculosis; the reservoir of infection typically is found in persons with active pulmonary disease Oropharyngeal and intestinal tuberculosis contracted by drinking milk contaminated with Mycobacterium bovis Mycobacterium avium complex are much less virulent , rarely cause disease in immunocompetent , however in patients with AIDS , these strains cause disease in 10% to 30%

Pathogenesis in unexposed immunocompetent person :

* Cell mediated immunity develop after 3 week of exposure * Processed mycobacterial antigens reach the draining lymph nodes and are presented to CD4 T cells by dendritic cells and macrophages. * CD4+TH1 subset generated→ IFN γ released → activate macrophages → release mediators → Recruitment of monocytes and bacterial killing. * Immune response leads to caseation

This immune response, while largely effective, comes at the cost of hypersensitivity and the accompanying tissue destruction “ necrosis “. * Reactivation of the infection or re-exposure to the bacilli in a previously sensitized host results in rapid mobilization of a defensive reaction but also increased tissue necrosis

Signs & Symptoms Common cold symptoms Early symptoms Common cold symptoms Fatigue, fever, a minimally productive cough of yellow or green sputum and a general feeling of malaise. Later symptoms Night sweats, fever, cough with purulent secretions and haemoptysis, dyspnoea, chest pain, and hoarseness.

Types of TB infection: Primary TB :Infection in unsensitized or immunocompromised host Secondary ( reactivation TB) Progressive pulmonary TB Miliary TB Isolated organ TB

Primary Tuberculosis Is the form of Disease that develops in a previously unexposed , and therefore unsensitized person

Primary Tuberculosis Ghon focus “caseation “ + As sensitization develops , a 1 to 1.5 cm are of gray white inflammation develop sub pleural caseating granuloma Ghon Focus Ghon focus “caseation “ + hilar lymphadenopathy Ghon Complex

Primary Tuberculosis When Ghon complex undergoes progressive fibrosis , often followed by radiologically detectable Calcification ( Ranke Complex ) which is healed TB.

Outcome of Primary TB In 95% cell mediated immunity develop  control the infection  healing: - Fibrosis  calcification : Ranke complex Foci of scarring may harbor viable bacilli for years, perhaps for life, and thus be the place for reactivation at a later time when host defenses are compromised Uncommonly disseminated disease Progressive Primary TB

Primary infection Primary TB Miliary TB Healed TB Latent TB Secondary TB Primary TB Progressive TB Miliary TB

GHON COMPLEX

Caseating granulomata

Thank you Done by : AloOsh M.Ali