Flashcards in Viral Respiratory Tract Infections Deck (31):
What are the most common causes of the common cold?
Mostly rhinoviruses (80%)
Some coronaviruses (15-20%)
Which infections does rhinovirus cause?
The common cold
Describe the coronavirus.
Large RNA virus
Found in animals and can jump species
Associated with severe infections, although are mostly mild
What is croup?
This is commonly encountered as a childhood infectious syndrome
Mostly mild but responsible for significant emergency visits (rapid onset with difficult breathing)
What normally causing croup?
Parainfluenza viruses 1-4
- normally occurs in the winter
- type three occurs in the spring
How is croup treated?
Supportive only (steroids)
Not any curative treatment
What is the pathophysiology of Bronchiolitis?
Infection of the lower respiratory tract with the respiratory syncitial virus causes the bronchioles to become infected and inflamed. The inflammation reduces air entry into the lungs
Who are most commonly affected by bronchiolitis?
Babies and young children under the age of 2
- very common, most children are at least asymptomatically affected by the virus
What are the symptoms of bronchiolitis?
Dry and persistent cough
What is the treatment for RSV (cause of bronchiolitis)?
Ribivirin (oral, IV or aerosolised)
- benefit unclear
- has many side effects, so only used in very severe infections
- a prophylactic monoclonal antibody
- give IM monthly
Name some symptoms of pneumonia.
Cough with sputum
Shortness of breath
Pleuritic chest pain
What is the most common cause of viral pneumonia?
Describe the nucleic acid of an influenza virus.
RNA virus made up of eight different segments
What are the three forms of the influeza virus?
A -most dangerous type (forms neurominidase)
B - only circulates in humans
C- mild and untested for
What are the symptoms of influenza?
Systemic features (headache, runny nose, cough, sore throat)
What is direct viral primary pneumonia?
Infection goes straight to the lungs and doesn't cause any other side effects (just pneumonia symptoms)
What are the common complications of an influenza infection?
Acute otitis media
Exacerbation of underlying diseases
What are the uncommon complications of an influenza infection?
Which populations are most at risk of complications from an influenza infection?
Extremes of ages
Chronic lung and heart disorders
Describe the epidemiology of an influenza epidemic.
The kids are affected first because they all interact at school and infect each other
The parents of these children are then infected
Then adults in general are affected as they interact with each other
Why do influenza epidemics occur every year?
From one year to the next, the influenza virus mutates and changes in order to avoid our immune response (antigenic drift)
This means when the health board try and vaccinate people, they have to make educated guesses as to which mutations will have occurred in the past year
What is the treatment for influenza?
- prevent release of the virus from the infected cell, stopping transmission
What is an influenza pandemic
A worldwide epidemic of a newly emerged strain of influenza
- few people are immune to the virus
- new virus can spread widely and easily and cause more serious illness
Describe the three ways in which antigenic shift can occur for the influenza virus.
1) Aquatic bird strain jumps straight to intermediate host then to humans without genetic change
2) Human or aquatic strain jumps to the intermediate host, where two viruses enter the same cell and reassortment occurs. Then the new strain is passed back to humans
3) Aquatic strain passes straight to humans without any genetic change
Where does the influenza strain arise from?
Don't know, could be anything
- e.g. chickens, ducks and other kinds of birds
What is SARS coronavirus?
The virus that causes severe acute respiratory syndrome (SARS)
Causes muscle pain, headache and fever followed by the onset of respiratory symptoms (cough, dysnpnea and pneumonia)
What is MERS coronavirus?
The virus that causes middle east respiratory syndrome (MERS)
An acute respiratory illness with symptoms of fever, cough and shortness of breath
What is enterovirus 68?
A virus that can cause mild to severe respiratory illness
- runny nose, sneezing, coughing, body aches and muscle aches
- wheezing and difficulty breathing
Spread through sputum/coughing/etc.
How are respiratory tract infections diagnosed?
Sputum/throat swab - PCR testing to find the nucleic acid of the pathogen
Urine (to rule out bacterial cause)
- analysis of biological markers in the genome and proteome
What are the benefits of molecular testing?
Rapidly developed to detect new pathogens
Can be used to detect multiple pathogens
Rapid turn around time