II. Respiratory Diseases

Mucociliary Escalator

Composed of cilia lining the trachea and bronchi that propels material, including microbes trapped in mucus, up and out of the respiratory tract.

Function of Mucociliary Escalator

Propels material up and out of the respiratory tract, assisted by swallowing, coughing, and sneezing.

Impact of Influenza on Mucociliary Escalator

Infections like influenza can cause infected epithelial cells to die, compromising this defense mechanism.

Normal Flora of Respiratory System

Competes with invading pathogens and helps prevent colonization.

Pathogens Among Normal Flora

Resident microflora may include potential pathogens like Streptococcus pyogenes, Staphylococcus aureus, Streptococcus pneumoniae, and Neisseria meningitidis.

COVID-19

Abbreviation for coronavirus disease 2019, caused by SARS-CoV-2.

SARS-CoV-2

A single-stranded RNA virus responsible for COVID-19.

Structure of SARS-CoV-2

Includes spike proteins, nucleocapsid protein, envelope protein, membrane protein, and hemagglutinin esterase dimer protein.

Spike Proteins (S)

Mediate attachment to host cells via ACE-2 receptors and form distinct surface spikes.

Nucleocapsid Protein (N)

Binds to and packages the viral RNA genome.

Envelope Protein (E)

A transmembrane protein involved in virus assembly and release; needed for pathogenesis.

Membrane Protein (M)

The most abundant protein, promotes membrane curvature and binds the nucleocapsid.

Hemagglutinin Esterase Dimer Protein (HE)

Enhances cell entry and virus spread in some coronaviruses.

ACE-2 Receptors

Receptors on cells that SARS-CoV-2 attaches to for entry and replication.

COVID-19 Symptoms

Common symptoms include fever, cough, and shortness of breath, appearing 2-14 days after exposure.

Long Covid

A condition where approximately 5-8% of patients experience persistent symptoms beyond 4 weeks after initial infection.

Prevention of COVID-19

Includes disinfection and mask use to reduce the spread of viral particles.

Treatment for COVID-19

No specific medicine for prevention or treatment; self-care like rest and fluids is suggested.

Testing for COVID-19

Tests are primarily PCR-based or serological for detection of RNA or antibodies.

Influenza Complications

Annual epidemics cause 3,000-49,000 deaths/year in the US, particularly affecting those aged 65 and older.

Seasonal Flu Vaccine

Targets strains predicted to be most common, typically quadrivalent, to protect against four viruses.

1918 Spanish Flu

Killed over 50 million people globally and affected previously healthy young adults through a cytokine storm.

H1N1 Pandemic 2009

First seen in the US in Spring 2009 and resulted in a mild to moderate illness for most but severe in high-risk groups.

Avian Flu (Bird Flu)

Strains H5N1 and H7N9 cause high mortality rates in humans and have potential for increased transmission.

Influenza Symptoms

Include cough, weakness, fatigue, and muscle aches.

Transmission of Influenza Virus

Spread via aerosol and inhaled into the lungs, often leading to secondary lung infections.

Antigenic Drift

Frequent mutations in influenza virus surface glycoproteins leading to immune response variability.

Antigenic Shift

Occurs when two different flu viruses infect the same host and swap genetic segments.

Pneumonia Definition

Inflammation of the lungs where alveoli fill with fluid.

Common Bacterial Pathogens of Pneumonia

Include Streptococcus pneumoniae, Legionella pneumophila, and Klebsiella pneumoniae.

Common Viral Pathogens of Pneumonia

Include SARS, COVID-19, Hantavirus, Influenzas, and Respiratory syncytial virus.

Tuberculosis (TB) Cause

Caused by Mycobacterium tuberculosis.

Characteristics of Mycobacterium tuberculosis

Acid fast, lipid-rich cell wall, rod-shaped, resistant to disinfectants.

TB Transmission Route

Spread via the respiratory route.

TB Symptoms

Include chronic fever, weight loss, and cough.

Prevention of TB

A vaccine is used in some countries.

Treatment for TB

Requires long-term antibiotic therapy, often up to 12 months, due to resistance issues.

Whooping Cough Cause

Caused by Bordetella pertussis.

Symptoms of Whooping Cough

Include violent cough attacks characterized by a 'whooping' sound.

Treatment for Whooping Cough

Treatment with antibiotics is available; vaccination and boosters are essential for prevention.

Common Cold Virus

Over 75% of cases are caused by Rhinoviruses.

Rhinoviruses Characteristics

Small, icosahedral particles with a single-stranded RNA genome, causing common cold symptoms.

Common Cold Transmission Mode

Aerosol spread is the most common mode of transmission, primarily via sneezing.

Impact of Common Cold

Causes 62 million cases yearly in the U.S., resulting in 45 million missed days of school or work.

Common Cold Symptoms

Coughing, sneezing, runny nose caused by the immune response to infection.

Duration of Common Cold Symptoms

Typically last about one week.

Role of Stress in Common Cold Severity

Stress can increase the severity of symptoms.