Fundamentals of TB Year 4 Internal Medicine Notes OmpathStudy

Fundamentals of TB Year 4 · Internal Medicine Collection: 4TH YEAR ALL NOTES / IMED / IMED 4.3 / MOGERE -- Slide 1 Fundamentals of Tuberculosis (TB) Dr Alex Mogere Consultant physician <number Slide 2 Introduction TB is the world’s second most c’m cause of death from infectious disease after HIV/AIDS TB may spread to any part of body India is the highest TB burden country in the world, home to 20% of cases occurring w/wide <number Slide 3 TB in Kenya,Africa The WHO estimated there were 169,000 cases of TB in Kenya in 2016 and 29,000 deaths (excluding deaths linked to HIV and TB coinfection),\nmaking TB the fourth-leading cause of death in the country HIV/AIDS continues to be an important driver of the TB epidemic in Kenya, with approximately 31% of TB patients (with known HIV status) also living with HIV. Nearly 2.5 million people contracted TB in sub-Saharan Africa in 2019 and more than 660,000 died of the disease,” <number Slide 4 Factors Contributing to the Increase in TB Cases HIV epidemic Increased immigration from high-prevalence countries Transmission of TB in congregate settings (e.g., correctional facilities, long term care) Deterioration of the public health care infrastructure <number Slide 5 Transmission and Pathogenesis of TB Caused by Mycobacterium tuberculosis (M. tuberculosis)\nSpread person to person through airborne particles that contain M. tuberculosis, called droplet nuclei Transmission occurs when an infectious person coughs, sneezes, laughs, or sings Prolonged contact needed for transmission\n10% of infected persons will develop TB disease at some point in their lives <number Slide 6 Sites of TB Disease Pulmonary TB occurs in the lungs 85% of all TB cases are pulmonary\nExtrapulmonary TB occurs in places other than the lungs, including the: Larynx\nLymph nodes Brain and spine Kidneys\nBones and joints Miliary TB occurs when tubercle bacilli enter the bloodstream and are carried to all parts of the body <number Slide 7 <number Not Everyone Exposed\nBecomes Infected Probability of transmission depends \non:\nInfectiousness\nType of environment \nLength of exposure\n10% of infected persons will develop\nTB disease at some point in their lives\n5% within 1-2 years\n5% at some point in their lives Slide 8 Persons at Risk for Developing TB Disease Persons at high risk for developing TB disease fall into 2 categories Those who have been recently infected Those with clinical conditions that increase their risk of progressing from LTBI to TB disease <number Slide 9 Recent Infection as a Risk Factor Persons more likely to have been recently infected include Close contacts to persons with infectious TB Skin test converters (within past 2 years) Recent immigrants from TB-endemic areas\nChildren ≤ 5 years with a positive TST Residents and employees of high-risk congregate settings (e.g. correctional facilities, homeless shelters, healthcare facilities) <number Slide 10 Increased Risk for Progression to TB Disease Persons more likely to progress from LTBI to TB disease include HIV infected persons Those with history of prior, untreated TB Underweight or malnourished persons Injection drug use Those receiving TNF-α antagonists for treatment of rheumatoid arthritis or Crohn’s disease Certain medical conditions <number Slide 11 Risk factors (summary)for PTB <number Slide 12 <number Slide 13 <number Slide 14 Ct. Phathopshysiology Starts replication inside the mθs Primary infection occurs CMI(cell mediated immunity) gets activated, surronds the cells to form granuloma(3 weeks) Leads to necrosis of tissue at infection site (Ghon focus complex) Involve nearby LNs(cone complex) Calcification of cone complex <number Slide 15 <number Latent TB Infection (LTBI) Occurs when person breathes in bacteria \nand it reaches the air sacs (alveoli) of lung \n\nImmune system keeps bacilli contained \nand under control \nPerson is not infectious and has no \nsymptoms Slide 16 <number TB Disease Occurs when immune system cannot \nkeep bacilli contained\n\nBacilli begin to multiply rapidly \nPerson develops TB symptoms Slide 17 LTBI vs. TB Disease <number Slide 18 Targeted Testing Detects persons with LTBI who would benefit from treatment\nDe-emphasize testing of groups of people who are not at risk (mass screening) Consider using a risk assessment tool Testing should be done only if there is an intent to treat Can help reduce the waste of resources and prevent unnecessary treatment <number Slide 19 Groups to Target with the Tuberculin Skin Test Persons with or at risk for HIV infection Close contacts of persons with infectious TB Persons with certain medical conditions Injection drug users Foreign-born persons from areas where TB is common Medically underserved, low-income populations Residents of high-risk congregate settings\nLocally identified high-prevalence groups <number Slide 20 Administering the TST Use Mantoux tuberculin skin test\n0.1 mL of 5-TU of purified protein derivative (PPD) solution injected intradermal