9.COVID-19ptt Year 4 Internal Medicine Notes OmpathStudy

9.COVID-19ptt Year 4 · Internal Medicine Collection: 4TH YEAR ALL NOTES / IMED / IMED 4.1 / NGUGI -- Slide 1 COVID-19 1 Slide 2 INTRODUCTION 2 COVID-19 is the disease caused by the SARS-CoV-2 virus.SARS- CoV-2 is an enveloped β-coronavirus, with a genetic sequence very similar to SARS-CoV-1. It transmitted by airborne, droplet transmission, some research studies suggests feco oral transmission. Based on the cells that are likely infected, COVID-19 can be divided into three phases that correspond to different clinical stages of the disease. Slide 3 3 Slide 4 PATHOGENESIS 4 Stage 1: Asymptomatic state (initial 1–2 days of infection)\n\nThe inhaled virus SARS-CoV-2 likely binds to epithelial cells in the nasal cavity and starts replicating. ACE2 is the main receptor for both SARS-CoV2. The ciliated cells are primary cells infected in the conducting airways there is low level of ACE2 expression in conducting airway cells.There is local propagation of the virus but a limited innate immune response. At this stage the virus can be detected by nasal swabs which are more sensitive than throat swabs. Although the viral burden may be low, these individuals are infectious. The RT-PCR value for the viral RNA might be useful to predict the viral load and the subsequent infectivity and clinical course Slide 5 Stage 2: Upper airway and conducting airway response (next few days)\n\nThe virus propagates and migrates down the respiratory tract along the conducting airways, and a more robust innate immune response is triggered. Nasal swabs or sputum should yield the virus (SARS-CoV-2) as well as early markers of the innate immune response. At this time, the disease COVID-19 is clinically manifest. The level of CXCL10 (or some other innate response cytokine) may be predictive of the subsequent clinical course. Viral infected epithelial cells are a major source of beta and lambda interferons. CXCL10 has also been reported to be useful as disease marker in SARS. Determining the host innate immune response might improve predictions on the subsequent course of the disease and need for more aggressive monitoring. For about 80% of the infected patients, the disease will be mild and mostly restricted to the upper and conducting airways.These individuals may be monitored at home with conservative symptomatic therapy. 5 Slide 6 Stage 3: Hypoxia, ground glass infiltrates, and progression to ARDS\n\nUnfortunately, about 20% of the infected patients will progress to stage 3 disease and will develop pulmonary infiltrates and some of these will develop very severe disease. Initial estimates of the fatality rate are around 2%, but this varies markedly with age. The virus now reaches the gas exchange units of the lung and infects alveolar type II cells. Both SARS-CoV and influenza preferentially infect type II cells compared to type I cells. The infected alveolar units tend to be peripheral and subpleural.SARS- CoV propagates within type II cells, large number of viral particles are released, and the cells undergo apoptosis and die. The end result is likely a self-replicating pulmonary toxin as the released viral particles infect type II cells in adjacent units. I suspect areas of the lung will likely lose most of their type II cells, and secondary pathway for epithelial regeneration will be triggered. 6 Slide 7 Normally, type II cells are the precursor cells for type I cells. The pathological result of SARS and COVID-19 is diffuse alveolar damage with fibrin rich hyaline membranes and a few multinucleated giant cells The aberrant wound healing may lead to more severe scarring and fibrosis than other forms of ARDS. Recovery will require a vigorous innate and acquired immune response and epithelial regeneration. Elderly individuals are particularly at risk because of their diminished immune response and reduced ability to repair the damaged epithelium. The elderly also have reduced mucociliary clearance, and this may allow the virus to spread to the gas exchange units of the lung more readily. In conclusion, COVID-19 confined to the conducting airways should be mild and treated symptomatically at home. However, COVID-19 that has progressed to the gas exchange units of the lung must be monitored carefully and supported to the best of our ability, as we await the development and testing of specific antiviral drugs. 7 Slide 8 8 Slide 9 ACUTE COVID 9 COVID has an incubation period of 2 to 14 days, once symptoms appear, you have entered the acute stage. Symptoms of acute SARS-CoV-2 infection include fever, lethargy, myalgia, fatigue, headache, rhinorrhea, dry cough, dyspnea, smell or taste alterations, nausea, vomiting, and diarrhea. Active illness can last one to two weeks if you have mild or moderate coronavirus disease, but severe cases can last months. Some people are asymptomatic, meaning they never have symptoms,, though they the have covid Slide 10 10 Slide 11 LONG COVID Slide 12 INTRODUCTION Long COVID or post covid-19 condition is defined a