Respiratory Infection - 1 Flashcards
(57 cards)
What are the clinical presentations of influenza?
- Fever: high, abrupt onset (up to 40oC)
- Malaise
- Myalgia (muscle pain)
- Headache
- Cough
- Prostration (weakness)
What pathogens is classical flu caused by?
- influenza A viruses
* influenza B viruses
What pathogens ar flu-like illnesses caused by?
- parainfluenza viruses
* many others
What pathogens cause haemophilia influenzae?
- bacterium - not a primary cause of ‘flu
* may be a secondary invader
How is influenza transmitted?
Transmission is by droplets, or through direct contact with respiratory secretions of someone with the infection
During which procedures should aerosol protection transmission precautions be adopted?
Aerosol generating procedures only e.g.
- Intubation, extubation
- Cardiopulmonary resuscitation
- Bronchoscopy
- Many others
What are complications of influenza?
- Primary influenzal pneumonia
- Secondary bacterial pneumonia
- Bronchitis
- Otitis media
- Influenza during pregnancy may also be associated with perinatal mortality, prematurity, smaller neonatal size and lower birth weight
What is primary influenzal pneumonia?
- seen most during pandemic years
- can be disease of young adults
- high mortality
What is secondary bacterial pneumonia?
- more common in infants, elderly and debilitated, pre-existing disease, and pregnant women
- cause of mortality in all influenza epidemics
- Most common cause of death in fatal influenza, even in pandemic years
What are treatments for influenza?
- Sympptomatic - bed rest, fluids, paracetamol
* Antivirals - oseltamivir, zanamivir
Why are pregnant women encouraged to get flu vaccine?
Influenza during pregnancy may be associated with perinatal mortality, prematurity, smaller neonatal size and lower birth weight
Describe the epidemiology of influenza virus
- Epidemics - winter epidemics, epidemics seen in association with minor mutations in the surface proteins of the virus (antigenic drift)
- Pandemics - rare, unpredictable, influenza A only
What causes flu pandemic?
Influenza A only
* antigenic shift - segmented genome, animal reservoir/mixing vessel
Explain the process of antigenic shift
- Pig (for example) simultaneously infected with human-adapted influenza virus and duck-adapted influenza virus
- The pig’s cells will be infected with human and duck influenza gene segments
- The human can then be infected with a combination of the human-adapted virus and duck-adapted virus contracted form pig
- Human will have no immunity to virus at all as it has duck-adapted influenza proteins on its surface
- Virus is not slightly different version of human adapted virus ( antigenic drift), it is completely different (antigenic shift)
- Results in pandemic
What is an example of an influenza virus that has undergone antigenic shift?
H1N1
What are future threats for influenza pandemics?
- Highly pathogenic avian flu
- Bird to human transmission seen
- High mortality
- Not readily transmitted human to human
How can the presence of influenza virus be confirmed in a lab?
Direct detection of virus
- PCR - nasopharyngeal swabs /throat swabs
- Immunofluorescence
- Antigen detection
- Virus culture
How is a nasopharyngeal swab taken?
Putting swab down patients nose until touches back of nasopharynx
How is influenza prevented?
Vaccines
What are the 2 types of flu vaccines?
- Killed vaccines
* Live attenuated vaccines
What are killed vaccines?
- Virus grown in hen’s eggs or cell culture then inactivated and combined with an adjuvant
Who receives killed vaccines?
- given annually to adult patients at risk of complications
- Health care workers
- Children aged 6 months to 2 years at risk of complications
Who receives live attenuated vaccines?
- More effective than killed vaccine in children aged 2-17
* Offered this year to ALL children aged 2-5, and all primary school children
How are live attenuated vaccines administered?
Administered intra-nasally
