Viral Respiratory Tract Infections

Question 1

What are the most common causes of the common cold?

Answer 1

Mostly rhinoviruses (80%)
Some coronaviruses (15-20%)

Question 2

Which infections does rhinovirus cause?

Answer 2

The common cold

COPD

Question 3

Describe the coronavirus.

Answer 3

Large RNA virus
Found in animals and can jump species
Associated with severe infections, although are mostly mild

Question 4

What is croup?

Answer 4

This is commonly encountered as a childhood infectious syndrome
Distinctive cough
Mostly mild but responsible for significant emergency visits (rapid onset with difficult breathing)

Question 5

What normally causing croup?

Answer 5

Parainfluenza viruses 1-4

• normally occurs in the winter
• type three occurs in the spring

Question 6

How is croup treated?

Answer 6

Supportive only (steroids)
Not any curative treatment

Question 7

What is the pathophysiology of Bronchiolitis?

Answer 7

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

Question 8

Who are most commonly affected by bronchiolitis?

Answer 8

Babies and young children under the age of 2

- very common, most children are at least asymptomatically affected by the virus

Question 9

What are the symptoms of bronchiolitis?

Answer 9

Fever
Dry and persistent cough
Difficulty feeding
Wheezing

Question 10

What is the treatment for RSV (cause of bronchiolitis)?

Answer 10

Ribivirin (oral, IV or aerosolised) 
- benefit unclear
- has many side effects, so only used in very severe infections 
Palivizumab 
- a prophylactic monoclonal antibody
- give IM monthly
- expensive

Question 11

Name some symptoms of pneumonia.

Answer 11

High fever
Headaches
Cough with sputum
Shortness of breath
Pleuritic chest pain
Fatigue 
Nausea

Question 12

What is the most common cause of viral pneumonia?

Answer 12

Influenza virus

Question 13

Describe the nucleic acid of an influenza virus.

Answer 13

RNA virus made up of eight different segments

Question 14

What are the three forms of the influeza virus?

Answer 14

A -most dangerous type (forms neurominidase)
B - only circulates in humans
C- mild and untested for

Question 15

What are the symptoms of influenza?

Answer 15

Fever
Muscle ache
Systemic features (headache, runny nose, cough, sore throat)

Question 16

What is direct viral primary pneumonia?

Answer 16

Infection goes straight to the lungs and doesn’t cause any other side effects (just pneumonia symptoms)

Question 17

What are the common complications of an influenza infection?

Answer 17

Acute otitis media
Sinusitis 
Pneumonia
Exacerbation of underlying diseases
Dehydration (infants)

Question 18

What are the uncommon complications of an influenza infection?

Answer 18

Encephalopathy 
Reye syndrome
Myositis
Myocarditis
Febrile seizures

Question 19

Which populations are most at risk of complications from an influenza infection?

Answer 19

Extremes of ages
Chronic lung and heart disorders
Immunosuppressed 
Pregnant 
Hepatic disorders

Question 20

Describe the epidemiology of an influenza epidemic.

Answer 20

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

Question 21

Why do influenza epidemics occur every year?

Answer 21

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

Question 22

What is the treatment for influenza?

Answer 22

Neuroamidase inhibitors

- prevent release of the virus from the infected cell, stopping transmission

Question 23

What is an influenza pandemic

Answer 23

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

Question 24

Describe the three ways in which antigenic shift can occur for the influenza virus.

Answer 24

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

Question 25

Where does the influenza strain arise from?

Answer 25

Don’t know, could be anything

- e.g. chickens, ducks and other kinds of birds

Question 26

What is SARS coronavirus?

Answer 26

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)

Question 27

What is MERS coronavirus?

Answer 27

The virus that causes middle east respiratory syndrome (MERS)
An acute respiratory illness with symptoms of fever, cough and shortness of breath

Question 28

What is enterovirus 68?

Answer 28

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.

Question 29

How are respiratory tract infections diagnosed?

Answer 29

X-Ray (pneumonia)
Sputum/throat swab - PCR testing to find the nucleic acid of the pathogen
Urine (to rule out bacterial cause)
Molecular testing
- analysis of biological markers in the genome and proteome

Question 30

What are the benefits of molecular testing?

Answer 30

Highly sensitive
Rapidly developed to detect new pathogens
Can be used to detect multiple pathogens
Semi quantitative  
Rapid turn around time

Question 31

Why is the speed of the diagnosis important?

Answer 31

For infection control and the health of the patient