Emergent respiratory infections – COVID-19 Flashcards
(28 cards)
What is pneumonia and which parts of the lung does it affect?
A:
Pneumonia is the inflammation of the lung parenchyma located distal to the respiratory bronchioles.
It specifically involves the alveolar ducts, alveoli, and the interstitium.
What are the common respiratory symptoms and how are they divided between the upper and lower respiratory tract?
▪ URT: nasal obstruction, nasal congestion, sneezing, epistaxis, cough, sore
throat, hoarseness, and stridor
▪ LRT: dyspnea, chest pain, cough, sputum, hemoptysis, and wheeze
Compare SARS-CoV, MERS-CoV, and SARS-CoV-2 in terms of outbreak date/location, receptor, and animal reservoir?
➔ SARS-CoV:
▪ Date and location: November 2002, Guangdong-China
▪ Binding receptor: ACE2 in the lower respiratory tract
▪ Animal reservoir: bats
➔ MERS-CoV:
▪ Date and location: June 2012, Jeddah-Saudi Arabia
▪ Binding receptor: DPP4 in the lower respiratory tract, GIT, and kidneys
▪ Animal reservoir: dromedaries
➔ SARS-CoV-2:
▪ Date and location: December 2019, Wuhan-China
▪ Binding receptor: ACE2 in the lower respiratory tract
▪ Animal reservoir: bats and pangolin
Compare SARS-CoV, MERS-CoV, and SARS-CoV-2 in terms of outbreak date/location, receptor, and animal reservoir?
➔ SARS-CoV:
▪ Date and location: November 2002, Guangdong-China
▪ Binding receptor: ACE2 in the lower respiratory tract
▪ Animal reservoir: bats
➔ MERS-CoV:
▪ Date and location: June 2012, Jeddah-Saudi Arabia
▪ Binding receptor: DPP4 in the lower respiratory tract, GIT, and kidneys
▪ Animal reservoir: dromedaries
➔ SARS-CoV-2:
▪ Date and location: December 2019, Wuhan-China
▪ Binding receptor: ACE2 in the lower respiratory tract
▪ Animal reservoir: bats and pangolin
What is the structure of the coronavirus, including its size, genome type, and components?
➔ Medium-sized virus size, but has the largest mRNA genome
➔ Enveloped positive sense single-stranded RNA
➔ Genome: mRNA encased in nucleocapsid
Why is the coronavirus named “corona” and what is the role of the spike proteins?
➔ Corona = Crowns for Spikes:
✓ Glycoprotein Spike (S) Peptomer
✓ Spikes: to attach to human cell receptors
What structural proteins are encoded by the coronavirus genome and what are their functions?
- The genome encodes four or five structural proteins:
➔ S: spikes on the outside: mediates receptor binding
➔ M: membrane protein: assists viral assembly
➔ N: nucleocapsid protein: regulation of viral RNA synthesis, may interact with M
protein during virus budding
➔ E: small envelope protein: function is not fully understood
➔ HE – hemagglutinin-esterase glycoprotein: enhances uptake into mucosal cells
How does SARS-CoV-2 attach to human cells and where are ACE2 receptors highly expressed?
• SARS-CoV-2 attaches to human cells by binding to ACE2 receptors.
ACE2 receptors are highly expressed in:
1. Type 2 alveolar cells (highest concentration)
2. Bronchial epithelial cells
3. Tongue > buccal (cheek) epithelial cells
- SARS-CoV-2 binds to ACE-2 Receptor 10-20x more strongly than SARS-CoV
What are the major COVID-19 variants and where were they first identified?
- Alpha: UK
- Beta: South Africa
- Gamma: Brazil
- Delta: India
- Omicron: multiple countries
What are the most common symptoms experienced by people with COVID-19, and which one indicates pneumonia?
➔ Fever (83–99%)
➔ Cough (59–82%)
➔ Shortness of breath (31–40%) [serious and indicates pneumonia]
➔ Myalgia’s (11–35%)
What is the incubation period of COVID-19 and how long does it usually last?
Pre-symptomatic incubation period extends from 2-14 days, may last a median of 5 days
- During 1st week of illness, symptoms are flulike, with loss of taste and smell
- Severe disease may develop in 2nd week, with dyspnea and the need for ICU treatment
- Many patients remain asymptomatic during their illness
When is a person with COVID-19 most infectious, and how long does viral RNA remain detectable?
➔ Peaks between (two days before and one day after) symptom onset
➔ Declines within seven days
- Median duration of viral RNA detection in specimens: 18 days following the onset
What is the main mode of SARS-CoV-2 transmission, and under what conditions does it occur?
- Person-to-person spread is the main mode of SARS-CoV-2 transmission
- Close-range contact (within two meters) via respiratory particles
What are the classifications of COVID-19 severity and their key features?
- Mild (≈81%)
• Symptoms of COVID-19
• No viral pneumonia or hypoxia- Moderate
• Clinical signs of pneumonia
• O₂ saturation ≥ 94% - Severe (≈14%)
• Severe pneumonia
• O₂ saturation < 94%
• Ground-glass opacities on imaging - Critical (≈5%)
• May include:
🔸 Acute Respiratory Distress Syndrome (ARDS)
🔸 Sepsis or Septic shock
- Moderate
What is the case fatality rate of COVID-19, and what is its most common serious complication?
➔ The overall Case Fatality Rate (2.2%)
➔ Viral pneumonia is the most frequent serious clinical manifestation of COVID-19
which typically presents with:
hypoxemia, and bilateral opacities on CXR
What are the major risk factors for developing severe COVID-19 disease?
• Type 2 Diabetes Mellitus (DM)
• Chronic Kidney Disease (CKD)
• Obesity (BMI ≥ 30)
• Immunocompromised state, including:
• Solid organ transplant recipients
• Cancer
• Heart conditions:
• Heart Failure (HF)
• Coronary Artery Disease (CAD)
• Cardiomyopathy (CMP)
• Chronic Obstructive Pulmonary Disease (COPD)
• Pregnancy
• Smoking
What is RT-PCR and what does it detect in COVID-19?
A1:
RT-PCR (Real-time Polymerase Chain Reaction) detects viral RNA of SARS-CoV-2.
It is 60–80% sensitive.
What are the sample types used for RT-PCR testing in COVID-19?
A2:
• Nasal and oropharyngeal swabs (2 swabs – most common)
• Sputum (more accurate but riskier to collect)
• Stool (not generally used)
• Blood/Urine (virus not detected in these)
When is RT-PCR most reliable in the course of infection?
A3:
RT-PCR is most reliable during the first 7 days of symptom onset.
Does a negative RT-PCR rule out COVID-19?
A4:
No — a single negative RT-PCR does not exclude COVID-19.
If suspicion remains, repeat the test and consider isolation.
What is the primary clinical use of the COVID-19 rapid antigen test?
A1:
It is used to diagnose current infection with SARS-CoV-2.
How does the sensitivity of the rapid antigen test compare to PCR?
A3:
.
It is less sensitive than RT-PCR.
Its sensitivity is highest within 5–7 days of symptom onset in symptomatic patients
What lab tests are commonly used to assess COVID-19 severity?
• D-dimer: Elevated → suggests hypercoagulability and risk of thrombosis.
• CRP: Elevated → indicates systemic inflammation.
• LDH: Elevated → reflects tissue (especially lung) damage.
• Troponin: Elevated → indicates myocardial injury.
• Ferritin: Elevated → marker of severe inflammation and possible cytokine storm.
• CPK: Elevated → suggests muscle or cardiac damage.
• Absolute lymphocyte count: Decreased → indicates lymphopenia, associated with worse prognosis.
What laboratory abnormalities are commonly seen in hospitalized COVID-19 patients with coagulopathy?
A:
Hospitalized COVID-19 patients with coagulopathy may show:
• Mild thrombocytopenia (↓ platelets)
• ↑ D-dimer levels (marker of clot breakdown)
• ↑ Fibrin degradation products (FDPs)
• Prolonged prothrombin time (PT)
- Elevated D-dimer levels are associated with greater risk of death
