Dr. Meg-angela Christi Amores Infectious Diseases Dr. Meg-angela Christi Amores

Infectious Diseases Tuberculosis Leprosy AIDS Syphilis Viral Infections Pneumonia Herpes

TUBERCULOSIS one of the oldest diseases to affect humans caused by bacteria of the Mycobacterium tuberculosis complex Usually affects the lungs untreated, the disease may be fatal within 5 years in 50–65% of cases airborne spread of droplet nuclei

M. Tuberculosis rod-shaped, non-spore-forming, thin aerobic bacterium measuring 0.5 um by 3 um Neutral on gram staining Acid-fast (once stained, cannot be decolorized by acid alcohol) Acid fastness is due to the organisms high content of mycolic acid

Epidemiology More than 5 million new cases of tuberculosis were reported to the WHO in 2005 > 90% are from developing countries The WHO estimated that 8.8 M new cases of tuberculosis occurred worldwide in 2005 Asia: 4.9 M Africa 2.6 M Middle East 0.6 M Latin America 0.4 M

From exposure to infection M. tuberculosis is common transmitted through droplet nuclei, which are aerosolized by coughing, sneezing or speaking Determinants of the likelihood of transmission includes: Intimacy and duration Degree of infectiousness Shared environment

From exposure to infection Patients whose sputum contains AFB are most likely to transmit infection Most infectious patients have cavitary disease

From infection to disease the risk of developing disease after being infected depends largely on endogenous factors, such as the individual's immunity and the level of function of cell mediated immunity primary tuberculosis – Clinical illness directly following infection common among children up to 4 years of age and among immunocompromised persons Not associated with high level transmissibility

secondary (or postprimary) tuberculosis Dormant bacilli persisting for years before reactivating Mostly in adults Pulmonary findings

secondary (or postprimary) tuberculosis Age is an important determinant of the risk of disease after infection Risk is highest among late adolescent and early childhood Women are more prone to acquire infection than men in early adolescence The most potent factor for M tuberculosis infection is HIV co-infection

Pathogenesis and Immunity Infection and Macrophage Invasion Virulence of Tubercle Bacilli Innate Resistance to Infection The Host Response phagosomes and lysosomes occurs bacilli begin to multiply, ultimately killing the macrophage

Pathogenesis and Immunity Granuloma Formation (Tubercles) macrophages The Macrophage-Activating Response Caseous necrosis The Delayed-Type Hypersensitivity Reaction Role of Macrophages and T lymphocytes Mycobacterial Lipids and Proteins

Immunity Skin Test Reactivity PPD Skin test: Due to delayed-type sensitivity Coincident with immunity Mainly due to previously sensitized CD4 T lymphocytes Positive Tuberculin Skin Test (TST): wheal > 5mm on un-vaccinated persons >10 mm on vaccinated persons After 72 hours

Clinical Manifestations PULMONARY EXTRA-PULMONARY

Pulmonary TB Primary Mostly seen in children most inspired air is distributed to the middle and lower lung zones, these areas of the lungs are most commonly involved in primary tuberculosis In majority of cases, lesion heals spontaneously and may later be evident as a small calcified nodule (Ghon lesion) immunocompromised persons develop miliary TB

Pulmonary TB Secondary (Postprimary) adult-type, reactivation localized to the apical and posterior segments of the upper lobes, where the substantially higher mean oxygen tension favors mycobacterial growth small infiltrates to extensive cavitary disease

Clinical Manifestations fever and night sweats, weight loss, anorexia, general malaise, and weakness cough eventually develops—often initially nonproductive and subsequently accompanied by the production of purulent sputum, sometimes with blood streaking Hemoptysis may also result from rupture of a dilated vessel in a cavity (Rasmussen’s aneuruysm) Often with no physical findings The most common hematologic finding is mild anemia and leukocytosis

Extrapulmonary TB Lymph-Node Tuberculosis Pleural TB frequent among HIV-infected patients historically referred to as scrofula Pleural TB TB of upper airways Genitourinary TB TB Meningitis and Tuberculoma Gastrointestinal TB

Extrapulmonary TB Skeletal TB reactivation of hematogenous foci or to spread from adjacent paravertebral lymph nodes spine in 40% of cases, the hips in 13%, and the knees in 10% Spinal tuberculosis (Pott's disease or tuberculous spondylitis) With advanced disease, collapse of vertebral bodies results in kyphosis (gibbus)

Extrapulmonary TB Miliary TB Disseminated TB yellowish granulomas 1–2 mm in diameter that resemble millet seeds chest radiography reveals a miliary reticulonodular pattern

Diagnosis High index of suspision XRAY consistent with TB AFB microscopy: Sputum exam Tissue biopsy Culture Gold standard

Treatment DOTS ( Direct Observed Treatment Strategy) Treatment partner