Week 1 - Introduction to Respiratory Diseases Flashcards
What parts encompass the UPPER respiratory tract?
- Nasal cavity, paranasal sinuses, pharynx, hypopharynx,
larynx, oesophagus and trachea - The upper resp. is:
- Infections fairly common
- Usually viral
What parts encompass the LOWER respiratory tract?
- Bronchi, lungs, and pleura
- In the lower resp:
- Infections more dangerous
- Can be viral and bacterial, even fungal
The respiratory tract is …
A major portal of entry for infectious organisms
What causes an infection to occur in the respiratory tract?
The pathogen invades (i.e., breaches an
anatomical barrier or progresses beyond the
point of colonization),
Host Defense Mechanisms: What are Physical Barriers?
- Nose hair: can potentially trap invading organisms
- Cilia: line the trachea and constantly move foreign invaders up towards the pharynx to be swallowed
- Mucociliary response: wet mucus inside nasal cavity can engulf viruses / bacteria that enter upper airways
Host Defense Mechanisms: What is the innate immune system?
- Primary defense mechanism against invading organisms
- Respiratory epithelium covered with receptors and non-specific immune cells
- Not antigen specific; reacts to variety of organisms
Host Defense Mechanisms: What is the Adaptive Immune System?
- Includes both humoral and cell-mediated components
- Highly specific to each particular pathogen the body has
encountered
What is the pathophysiology of a URTI?
Infection of upper respiratory tract leads to activation of several inflammatory pathways and of the parasympathetic nervous system causing
- Engorgement of the vessels in the nasal turbinates
- Leakage of plasma into the nose and sinuses
- Discharge of mucus
- Stimulation of pain nerves
- Symptoms like sneezing and coughing
- Activation of the adaptive immune response (is antigen specific)
What are symptoms of URTI?
- Many, but not all infections, lead to harm to the
host and symptoms become evident - Common symptoms of URTI generally include:
- runny nose (rhinorrhea)
- cough (from laryngeal swelling and post-nasal
drip) - nasal congestion
- sore or scratchy throat (pharyngitis)
- painful swallowing (odynophagia)
- fever (more common in children)
- sneezing
- malaise
When does most URTI occur?
Most URTIs occur during fall/winter but can happen any time
* Average child: 4-8 URTIs per year; Average adult: 2-4 URTIs per year
What are the majority of URTI caused by?
Vast majority of upper respiratory infections are caused by viruses and are self- limited
What is the estimated economic impact of non–influenza-related URTIs?
The estimated economic impact of non–influenza-related URTIs is $40 billion annually
What is the etiology of URTI?
- Most are viral
- EX: Flu, COVID, rhinovirus - A few bacterial syndromes are
relatively common
- Ex: Streptococcal pharyngitis, Bacterial sinusitis
What is the pathophysiology of the LRTI?
- Mucous membrane of the lower respiratory tract becomes hyperemic
(excess blood) and edematous (excess water/fluid); copious secretions - There can be destruction of the respiratory epithelium
- Bronchial mucociliary function can be diminished
- Alveoli become hyperinflated or congested, filled with fluid and sometimes
pus, don’t function as well
What are the symptoms of LRTI?
Symptoms of lower respiratory infection, depending
on location, may include :
- Cough from upper respiratory tract infection and bronchial and alveolar congestion
- Increased respiratory rate (tachypnea)
Difficulty breathing/shortness of breath (dyspnea)
- Difficulty breathing lying flat (orthopnea)
- Fever
- Increased heart rate
- Malaise and myalgia (fatigue and body aches)
What are the Etiology of LRTI?
- Gram-positive bacteria
- Gram-negative bacteria
- Atypical bacteria
- Respiratory viruses
- Fungi
What are risk factors for LRTI?
- Varied depending on syndrome
- Age: Very young and very old (pneumonia), <2 years (bronchiolitis)
- Frailty
- Underlying neurologic disability
- Underlying pulmonary disease
- Smoking and indoor pollution
- Immune compromise
Transmission Definition: Droplet
Large-particle infectious droplets >5 micrometers that do not remain
suspended in the air
Transmission Definition: Airborne
Smaller evaporated droplets or infected dust particles that remain suspended in the air
Transmission Definition: Contact
- Direct: body-to-body surface contact and physical transmission of pathogen
- Indirect: transmission after contact with contaminated inanimate object (e.g.
table, dressing)
What are the types of laboratory testing?
- Virus isolation (cell culture)
- PCR amplifies a specific region of the DNA strand to generate DNA sequences and identify
organism - Bacterial culture
- Antigen detection:
- Serology
What is the Disease burden of Resp diseases?
- Major cause of disease worldwide
- Population-based estimates are
important for: - Better understanding the epidemiology
- Planning for resource and healthcare needs
- Evaluating impact of prevention programs,
including vaccination
What are some challenges to understanding disease burden?
- Not everyone seeks medical care
- Complications can be broader than respiratory illness
- Surveillance not conducted everywhere
- Symptoms similar among respiratory pathogens
- Illnesses not often confirmed with laboratory testing
- Many adults no longer shedding virus when tested
- Pathogen rarely recorded on death certificates
