Respiratory Viruses Flashcards
A 28 year old junior medical doctor becomes ill in mid-January with a fever of 39.5oC, a sore throat, myalgia & lassitude. Apart from the pyrexia, the physical examination is normal.
Is this a ‘common cold’?
What should he do?
What are the possible complications?
Could this illness have been prevented?
No it’s not a common cold
It is influenza
He should go home, and wait it out
what is the common cause of bronchiolitis?
RSV
less commonly: influenza, parainfluenxa, adenovirus, rhinovirus
what are the most common causes of the common cold?
Rhinoviruses and coronavirus
what is the common cause of Croup?
parainfluenza virus
what are the viral causes of pneumonia?
Influenza Viruses
RS
Adenoviruses
how are respiratory viruses transmitted?
Direct: person to person via respiratory droplets
Indirect: person touches a surface or object contaminated with infectious droplets (fomites) then touches his or her mouch, nose, or eye
what are the symptoms of the common cold?
it is an upper respiratory viral illness involving sneezing, nasal congestion/discharge, sore throat, cough, headache and malaise
*no fever ususally as it is not a systematic illness
Describe the 3 types of Influenza virus
Influenza A: viruses effect range of mammalian and avian species - it is responsible for annual epidemics and occasional pandemics (birds are main reservoir)
Influenza B: viruses cause outbreaks every 2-4 years but not associated with pandemics
Influenza C: uncommon and typically causes milder disease
what is the difference between antigenic drift and antigenic shift?
antigenic drift = transcription errors by DNA polymerase result in amino acid substitutions in surface gycoproteins (can cause epidemics) *yearly epidemics*
antigenic shift= genes are swapped between different strains resulting in major antigenic change (this results in a novel virus with new surface or internal protein leading to PANDEMIC)
what is the difference between pandemic vs. non-pandemic influenza?
pandemic: result of antigenic shift (new emergence) - high attack rate and escess morbidity/mortality due to little-no immunity
non-pandemic: antigenic drift- evolution of existing strains - where there is some immunity in the populationt- therefore variable outbreaks varyingi n severity (but usually most severe in children/eldery)
what are the clinical characteristics of Influenza?
- abrupt onset of fever,
- cough and
- myalgia lasting only a few days with
- more persistant weakness and depression
what sort of complications might we see with influenza?
- primary influenza pneumonia
- secondary bacterial pneumonia
- myositis/myocarditis
- CNS: Seizures/encephalopathy/encephalitis
- Reye’s syndrome- liver failure
- Death
How do we diagnose influenza?
send nasopharyngeal aspirates/nose/throat swabs
do PCR to detect viral RAN
Why is it important for healthcare workers to be vaccinated against influenza?
- healthcare workers are often in contact with immune-deficient/at-risk patients
- about 30% of people infected with influenza are asymptomatic but can still be infecitous
- Influenza CAN KILL your vulnerable patients (newborn babies, elderly, pregnant women, chemotherapy patients, immunosuppressed patients)
- Even though the efficacy isn’t 100%, those who contract influenza after vaccination will have a milder form of disease and a reduced risk of spreading to vulnerable patients
- **** DYLAN GET YOUR DAMN FLU SHOT
What is the respiratory syncytial Virus?
the most common severe lower respiratory tract infection in infants and young children
May affect adults
typically causes upper respiratory symptoms in older children/adults
RSV is highly infectious and therefore is spread in crowded places
It causes 80% of cases of Bronchiolitis in children!!!
What is RSV Bronchiolitis?
it is an acute inflammatroy injury of the bronchioles
it is the most common cause of hospitalization in children less than 1 year of age
what are the signs/symptoms of RSV Bronchilitis?
respiratory distress with tachypnoea, nasal flaring and wheeze
apnoea
Irritability
Cyanosis
Prominent intercostal retraction indicating lower airway obstruction
flat diaphragm and hyperlucent lower lung fields indicating hyperinflation
Describe Parainfluenza virus
four serotypes
usually causes croup in children which present as a harsh brassy cough in the middle of the night
What are the symptoms of SARS?
*SARS CoV = Severe acute respiratory syndrome - coronavirus
symptoms
- fever of more than 38
- headache, general discomfort, severe muscle/body aches
- may be mild respiratory symptoms at outset
- some 10-20% have diarrhoea
- after 2-7 days a dry cough or shortness of breath may develop
- most patients develop pneumonia
What are the symptoms of MERS coronavirus?
*middle east respiratory syndrome
Mers is a resp. disease caused by a novel coronavirus
most human cases due to human/human transmission but camels are likely to be amajor reservoir host and an animal source of MERS infeciton in humans
symptoms: cough, fever, SOB, acute respiratory distress, 1/3 GI symptoms
