TUBERCULOSIS
DR. MOSHTAK WTWT
TB is the most infectious disease in the world with an estimation of 1/3 of population infected & 2.5 million deaths annually. If untreated, fatal in over 50% of cases. It was isolated by Robert Koch in 1882 Risk factors for increasing TB among developing countries: *ineffective control programs. *lack of access to health care. *poverty, civil unrest. *HIV. *population increase. *drug resistance.
While risk factors for increasing TB in developed countries: *immigration from high-prevalence areas. *HIV. *social deprivation(homeless, poverty). *increasing proportion of elderly. *drug resistence. ()Organism: A- mycobacterium tuberculosis complex(M. bovis, M. africanum). B- opportunistic mycobacterium (M. kansasii, M. xenopi etc…)
() Pathology & pathogenesis: *smallest particles (1-5 Mm) enter the periphery of the lung & are engulfed by MQ *in response to antigen, CD4 T lymphocyte produce interferon gamman that lead to recruitment of monocytes & formation of granuloma (tuberculous caseous granuloma). *this mass of granuloma called “Ghon focus”.
*Ghon focus + regional LN termed as Ghon complex. *occasionally , the tonsil, intestine or skin may be the site of primary disease. *in 85-90% healing occur in 1-2 months, TST become +. *in 10-15% lymphatic spread to pleura, pericardium, & pulmonary blood vessels (miliary, meningeal, bone, GIT). *In immunodeficiency like HIV patients: more likely to ()extrapulmonary & dissemeneted. ()reduced smear-positive rates. ()less cavitation. ()atypical CXR. ()adverse drug reaction.
()predisposing factors to TB: @ pateint related: *age . *first-generation immigrants from high-prevalence TB. *close contact to smear +ve pulm TB. *drug abuse *overcrowding. *CXR evidence with self-healed TB. *had primary infection < 1 year. @ associated disease: *immunosuppression: HIV, infximab, CS,. *Mlignancy. *type I dm. *CRF. *silicosis. *gastrectomy, malabsorption. *deficiency of Vit D OR A
() Timetable of TB: 1- first 3-8 weeks: +ve TT, erythema nodusum, fevers, phlyctenular conjuctivitis. 2- after 3-8 weeks: CXR show primary Ghon complex. 3- after 3-6 months: meningeal, miliary, pleural, pericardial. 4- up to 3 years: GIT, bone, joint,. 5- after 5 years: skin involvment. 6- around 8 years: renal tract diseases. 7- from 3 years on wards: post-primary disease
() clinical features: divided into: pulmonary & nonpulmonary regarding pulmonary divided into: primary pulmonary post primary miliary
() primary pulmonary TB: *refere to infection in previosly uninfected individual. *usually occur in childhood. *generally asymptomatic. *a history of contact with active pulmonary TB *clinical features include: @infection(4-8 weeks) influenza-like illness. +ve TT CXR primary complex. @disease: LAP, collapse, consolidation(RT middle lobe) cavitation, pleural effusion, miliary, pericarditis, erythema nodosum, phlyctenular conjuctivitis.
() post primary TB: *Is the most form of TB in adults. *typically insidoius. With fever, night sweating, maliase, anorxia, wt loss. *the disease often involves 2 or more areas of lung: opacity in upper lobe, consolidation, collapse, cavitation, miliary, pleural effusion,. *you should suspect post primary TB in: ()chronic cough often with hemoptysis. ()PUO ()unresolved pn. ()exudative pleural effusion. ()wt loss. ()spontenous pneumothorax.
Miliary TB: * Arise from blood dissemination. *presentes with 2-3 weeks (puo) of fever, night sweat, anorxia, wt loss, dry cough. Hepato splenomeagally, * ascultation of chest usually normal. *fundoscopy reveal choroidal tubercles. *anemia, & leucopenia. The term cryptic miliary TB presented as: *age > 60 years. *intermittent low-grade fever, PUO. *unexplained wt loss. *normal CXR *leukmiod reaction, pancytopnea. *confirmed by biopsy.
Extra-pulmonary TB: () Lymphadenitis: *most common site cervical , mobile , painless matted togther to form caseation “collar-stud” abscess & sinus formation. *TT strongly +ve, M. avium complex.
() GIT: 1- rarly involve tounge. 2- iliocecal 50% present as fever, wt loss, RIF mass. 3- up to 30% as acute abdomen. 4- mesentric adenitis & intestinal obstruction. 5- tuberculous peritonitis. 6- anorectal ulceration. 7- hepatic dysfunction. 8- DX --- U/S or CT may reveal thickend bowel wall abd LAP. BIOPSY is defenitive test.
() pericardial disease: pericardial effusion, constrictive pericarditis. Pericardial calcification. ()CNS: 1- lymphocytic meningitis, hydrocephalus & tuberculoma. 2- CN palsy.
() bone & joint diseases: 1- pott’s disease: the spine most common typically involve lower thoracic & lumbar spine. The infection starts as diskettes then spread to spinal ligament to involve ant vertebral bodies causing angulations with subsequent kyphosis. 2- par vertebral &psoas abscess. 3- TB can affect any joint (hip & knee)
()GUT: 1- Asymptomatic remains years. 2- sterile pyurea. 3- endometritis, epididymitis, prostatis. ()dermatology: lupus vulgaris & erythema nodosum.