Respiratory Infectious Disease - Background Flashcards
What is the anatomical site where most human infections take place?
Respiratory tract
How do most exposures to the respiratory tract occur?
Most exposures come from the simple act of breathing and from hand contact with the nose and mouth.
What microorganisms can infect the respiratory tract?
Viruses, Bacteria, Airborne Fungi
What syndromes are caused by organisms colonizing and damaging the upper respiratory tract?
- Common cold (rhinitis)
- Sinusitis
- Pharyngitis/laryngitis
- Croup (more common in children)
What are BY FAR the most common causes of upper respiratory tract infections?
VIRUSES
What is the most common upper respiratory infection?
Common colds
How many colds will a typical adult and typical child suffer from each year?
Adult - at least one
Children - several common cold infections
What cause the majority of colds? What percentage? What population particularly?
Rhinoviruses, ~50%, particularly in adults
At what temperature/environment do Rhinoviruses preferentially replicate?
33deg C (temperature found in the nose and upper airways) rather than 37deg C (temperature found in the lungs)
What pathogens are also important causes of the common cold?
- Parainfluenza
- Coronavirus
- Influenza C virus
- Coxsackievirus A + B
- Adenoviruses
Like many respiratory infections, when are colds more common?
Winter months
What symptoms characterize colds?
-Nasal discharge or congestion
-Mild sore throat
-Cough
-Lack of fever
(Children ma have a mild fever)
How long do colds usually last?
A week or less and the infection is self-limiting
What is the treatment for common colds?
No specific therapy is available.
What is a typical complication of a viral URI caused by a secondary bacterial infection?
Sinusitis
How do patients with sinusitis usually present?
- Fever
- Pus-filled (purulent) nasal discharge
- Sinus tenderness
What does mucus color and consistency NOT indicate in Sinusitis?
Bacterial rather than viral infection
What are common bacterial causes of sinusitis (2)? What percentage of Acute Bacterial Sinusitis infections do they cause? What is their representation?
-Streptococcus pneumoniae
-Haemophilus influenzae
They cause about 70% of acute bacterial sinusitis infections.
They equally contribute.
What is an Acute Rhinosinusitis infection?
When rhinitis infections and sinusitis infections coexist in an infected individual, these infections are called Acute Rhinosinusitis.
What is Pharyngitis?
Common URT infection
What is the common cause of pharyngitis in young children (less than 3 years old) and adults?
Viruses
What is the common cause of pharyngitis in older children (ages 5 to 15)?
Streptococcus pyogenes, followed by viruses
What is the only common cause of pharyngitis that should be treated?
Streptococcus pyogenes - because it can lead to serious complications
What does presentation of a fever and pharyngitis prompt in the doctors office that cannot be determined by clinical diagnosis alone?
Group A Strep test to rule out Streptococcus pyogenes infections. (to determine whether the cause is viral or bacterial)
