Respiratory Infection - 1 Flashcards
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
What does efficacy of a vaccine depend on?
Protective efficacy depends on match of vaccine to circulating virus and on patient group, but is never better than 70% effective in preventing clinical infection
What are causes of community acquired pneumonia?
Bacteria: -
- Mycoplasma pneumoniae
- Coxiella burnetii
- Chlamydia
What are the characteristics of mycoplasma, coxiella and chlamoydophila psittaci?
- Therapy - all respond to tetracycline and macrolides (eg clarithromycin)
- Mortality - varies with pathogen, but generally lower than classical bacterial pneumonia
- Often known as “atypical pneumonia” - relates to presentation and response to therapy in the pre-antibiotic era
How can mycoplasma, coxiella and chlamydophila psittaci be confirmed in the lab?
- By serology - send acute and convalescent bloods to lab, gold top vacutainer
- By virus detection- PCR on respiratory swabs / secretions
What is mycoplasma pneumoniae?
Bacteria which is a common cause of community acquired pneumonia
Who have the highest incidences of mycoplasma pneumoniae?
Children and young adults have highest incidences
How is mycoplasma pneumoniae transmitted?
Person to person spread
What diseases are caused by coxiella burnetti?
- Pneumonia
* Pyrexia of unknown origin (Q fever)
How is coxiella burnetti spread?
- Uncommon, sporadic zoonosis
* Sheep and goats
What is a complication of coxiella burnetti?
Endocarditis
What is endocarditis?
A rare and potentially fatal infection of the inner lining of the heart (the endocardium)
What pathogen causes psittacosis?
Chlamydophila psittaci
What is psittacosis caught from?
Pet birds
What does psittacosis usually present as?
Pneumonia
What individuals are at risk of bronchiolitis?
Children in their 1st or 2nd year of life
What are the symptoms of bronchiolitis?
- Fever
- Coryza
- Cough
- Wheeze
What are the signs of severe cases bronchiolitis?
- grunting
- decreased PaO2
- Intercostal / sternal indrawing
What are complications of bronchiolitis?
Respiratory and cardiac failure
When is respiratory and cardiac failure likely to occur as a result of bronchiolitis?
- prematurity
* pre-existing respiratory or cardiac disease
What is the aetiology of bronchiolitis?
Up to 80% cases due to Respiratory Syncytial Virus (RSV)
How is the presence of RSV (bronchiolitis) confirmed in the lab?
- By PCR on throat or pernasal swabs
or - Immunofluorescence on nasopharyngeal aspirate
What is the therapy for bronchiolitis?
- Supportive
* Previously nebuliser ribavirin but no longer used as no real effect
What is the epidemiology of bronchiolitis?
- Epidemics every winter
* Very common
How is spread of bronchiolitis prevented?
- No vaccine
- Prevent nosocomial spread in hospital wards by cohort nursing and handwahsing, gowns, gloves
- Passive immunisation (monoclonal antibodies) - poor efficacy and cost-efffectiveness
What is metapneumovirus?
Virus that causes lower respiratory tract infection (bronchiolitis, pneumonia)
What is the epidemiology of metapneumovirus?
- Most children antibody positive by age 5
- Found in a wide range of ages
- World-wide distribution
- Highest incidence in winter
What diseases are caused by metapneumovirus?
- Bronchiolitis (although RSV is main cause of bronchiolitis)
- 2% of cases of influenza-like illness
How is presence of metapneumovirus confirmed in the lab?
- PCR
What is chlamydia trachomatis?
STI which can cause infantile pneumonia
How is chlamydia trachomatis diagnosed?
Diagnosed by PCR on urine of mother or pernasal / throat swabs of child
What is chlamydophilia pneumoniae?
Type of bacteria that can cause lung infections such as pneumonia
How is chlamydophilia pneumoniae transmitted?
From person to person
How is presence of chlamydophilia pneumoniae confirmed in the lab?
May be picked up by test for psittacosis
