Theory 19 Infectious Diseases of the Respiratory System

Upper Respiratory Tract

Includes nasal cavity, pharynx, larynx.

Lower Respiratory Tract

Includes trachea, bronchi, bronchioles, alveoli.

Cilia

Hair-like structures that trap pathogens.

Microvillus

Small projections enhancing surface area for absorption.

Lysozyme

Enzyme that cleaves bacterial cell walls.

Lactoferrin

Sequesters iron to inhibit microbial growth.

Normal Flora

Commensal microbes in the upper respiratory tract.

Streptococcus pneumoniae

Common pathogen causing respiratory infections.

Pharyngitis

Inflammation of the throat, often painful.

Scarlet Fever

Rash caused by erythrogenic toxin from S. pyogenes.

Rheumatic Fever

Autoimmune response due to S. pyogenes infection.

Glomerulonephritis

Kidney inflammation from immune complexes.

Sinusitis

Infection of the sinus, acute or chronic.

Common Cold

Caused primarily by rhinoviruses, highly variable.

Tonsillitis

Inflammation of the tonsils, often viral or bacterial.

Epiglottitis

Inflammation of the epiglottis, can obstruct airway.

Acute Otitis Media

Middle ear infection, often follows respiratory infections.

Diphtheria

Bacterial infection causing severe throat swelling.

Bronchus

Major air passageways branching from trachea.

Alveoli

Tiny air sacs for gas exchange in lungs.

Mucociliary Escalator

Mechanism moving mucus out of the respiratory tract.

Beta-hemolytic

Type of bacteria that lyses red blood cells.

Bacitracin Sensitivity

Indicator for identifying Group A Streptococcus.

Antigenic Variability

Ability of viruses to mutate and evade immunity.

Respiratory Syncytial Virus (RSV)

Common cause of respiratory infections in infants.

Erythrogenic Toxin

Superantigen causing rash in scarlet fever.

Commensal Microbes

Non-pathogenic organisms that coexist with hosts.

Rhinoviruses

Primary cause of common cold cases.

Capsid Proteins

VP1, VP2, VP3 exhibit high antigenic variability.

Spike Protein

Critical for viral entry and immune evasion.

Rhinovirus Lifecycle

Stages include binding, entry, synthesis, assembly.

Pro-inflammatory Cytokines

Released by infected cells, causing cold symptoms.

Otitis Externa

Outer ear infection, often called swimmer's ear.

Haemophilus Influenza

Common bacteria causing acute otitis media.

Diphtheria Toxin

Blocks protein synthesis by modifying EF-2.

Pseudomembrane

Membranous network formed in diphtheria infection.

Influenza

Highly communicable acute respiratory infection.

Hemagglutinin

Spike protein aiding viral attachment to cells.

Neuraminidase

Spike protein facilitating viral release post-replication.

Influenza A

Causes yearly epidemics, infects animals and humans.

Influenza B

Less common, causes seasonal outbreaks in humans.

Influenza C

Causes mild respiratory illness, not epidemic.

Vaccination

Prevention method for diphtheria and influenza.

Eustachian Tube

Pathway for bacteria to enter middle ear.

Chronic Otitis Media

Persistent ear infection often involving biofilm.

Antibiotics

Used to treat bacterial infections like otitis media.

Incubation Period

Time from exposure to symptom onset, 2-5 days.

Corynebacterium diphtheriae

Gram-positive bacterium causing diphtheria.

Diphthamide

Modified histidine residue in EF-2 affected by toxin.

Vaccine Efficacy

Diphtheria vaccine efficacy approximately 95%.

Secondary Infections

Common after influenza due to weakened immunity.

Antigenic drift

Mutation causing reduced immune response to virus.

Seasonal influenza strains

Most arise from antigenic drift mechanisms.

H1N1

A subtype of influenza A virus.

Antigenic shift

Exchange of genome segments during co-infection.

Genetic shuffling

Random packaging of gene segments from viruses.

Epidemic

Disease occurrence exceeds normal levels in a region.

Pandemic

Worldwide epidemic affecting large populations.

Endemic disease

Habitually present at low levels in specific areas.

1918 influenza pandemic

Killed approximately 50 million globally post-WWI.

Influenza diagnosis

Based on signs, symptoms, and viral tests.

Rapid influenza tests

Provide results in 24 hours for virus identification.

Amantadine

Drug for treating influenza type A, taken early.

Zanamivir

Inhaled neuraminidase inhibitor for flu types A and B.

Tamiflu

Oral neuraminidase inhibitor for influenza types A and B.

Inactivated seasonal vaccine

70-90% effective against predicted flu variants.

Live attenuated vaccine

FluMist for ages 5 to 49, egg-based.

Recombinant vaccine

Protects against three influenza strains, egg-free options.

SARS-CoV

Causes Sudden Acute Respiratory Syndrome, 10% mortality.

MERS-CoV

Middle East Respiratory Syndrome, 35% mortality rate.

SARS-CoV-2

COVID-19 virus, first reported in 2019.

COVID-19 symptoms

Range from mild to severe illness post-exposure.

Acute respiratory distress syndrome

Infection leads to inflammation and impaired oxygen exchange.

Respiratory syncytial virus

Common cause of respiratory infections in newborns.

Pertussis

Whooping cough caused by Bordetella pertussis.

Filamentous hemagglutinin

Main adherence factor for B. pertussis colonization.

Pertussis toxin

Toxin causing severe coughing and gasping sounds.

Whole Cell Vaccine

Standard pertussis vaccine with 94% efficacy.

Acellular subunit vaccines

Detoxified components with fewer side effects.