Influenza, Pandemics & Other Respiratory Infections

Question 1

Where did influenza come from

Answer 1

Zoonotic

Question 2

Genera of influenza & which are more common in humans

Answer 2

A, B, C

A&B main human pathogens

Question 3

Subdivision of influenza A

Answer 3

Subdivided by 2 surface antigens:
- Haemagglutanin (15 subtypes)
- Neuraminidase (9 subtypes)
All 15H and 9N have been detected in birds.
E.g. H1N1

Question 4

Why can influenza change/mutate

Answer 4

Can get gene reassortment in infections
Gene swapping can occur during co-infection with human and avian flu virus
No proof reading mechanism so prone to mutation

Question 5

What causes seasonal flu epidemics?

Answer 5

Minor antigenic variation = antigenic drift

Question 6

What causes flu pandemics

Answer 6

Gene re-assortment & major antigenic variation = antigenic shift

Question 7

Where does gene re-assortment often occur for flu

Answer 7

Animal (pig) reservoir- get bird virus and human virus at same time –> viruses combine –> new virus adapted to spread rapidly in humans

Or virus straight from bird –> human (human reservoir)

Question 8

How do humans promote zoonotic infections

Answer 8

Humans in close proximity to animals - wet/live markets etc.
Intensive farming: bringing lots of animals in close proximity to each other
Farm parks/zoos

Question 9

Influenza A

Answer 9

Can infect pigs, cats, horses, birds, sea mammals, humans
Causes severe & extensive outbreaks and pandemics

Question 10

Influenza B

Answer 10

Tends to cause sporadic outbreaks (schools, care homes, garrisons) that are less severe
More often seen in children
Like A - prone to mutation

Question 11

Influenza C

Answer 11

Relatively minor disease
Mild symptoms or asymptomatic

Question 12

Influenza transmission

Answer 12

Mainly via aerosols generated by coughs & sneezes.
Possible via hand-hand contact, other personal contact & fomites

Question 13

Influenza infection symptoms & complications

Answer 13

Upper +/- lower respiratory tract symptoms + fever, headache, myalgia, weakness
Complications: include bacterial pneumonia, life threatening

Question 14

People with higher risk of flu mortality

Answer 14

Underlying medical conditions
chronic cardiac & pulmonary diseases
old age
chronic metabolic diseases
chronic renal disease
immunosuppressed

Question 15

Influenza treatment

Answer 15

Supportive care (oxygen, hydration, nutrition, maintain homeostasis, prevent/treat secondary infections)

Antivirals: reduce risk of transmission, reduce severity and duration of symptoms (only really see a difference at a population level)

Question 16

Seasonal flu

Answer 16

Antigenic drift every year - so can infect people who were immune to last years varient.
Usually peaks December - March (northern hemisphere)
Southern hemisphere - analyses their strains to make predictions for vaccines

Question 17

Avian Influenza - about

Answer 17

Avian pathogen but can transmit to humans.
Usually mild in birds but can mutate to 100% mortality form.
~50% death rate in humans
HIgh risk of becoming pandemic

Question 18

How to control avian influenza

Answer 18

Cull affected birds
Biosecurity & quarantine (e.g. 5-10km around a farm)
Disinfect farms
Control poultry movement
Vaccinate workers with seasonal flu jab
Antivirals for poultry workers
PPE
Try to reduce chance of coinfection

Question 19

What is the number 1 risk to UK

Answer 19

Pandemic flu

Question 20

Reasons for more pandemics

Answer 20

More travel
More people
Intensive farming (more animal contact with humans & factory farming)

Question 21

Why are we better equipped to deal with pandemics

Answer 21

• Better nutrition, overall healthier population
• Better supportive care
• Vaccination
• Antivirals

Question 22

Infection control responses to pandemics

Answer 22

Hand hygiene, cough etiquette
PPE
Surgical masks (for non aerosol generating procedures)
Segregation of patients
Reduce social contact
Flu surgeries (separate potentially infected patients)
Environmental cleaning
Ventillation

Question 23

Population wide interventions for pandemics

Answer 23

Travel restrictions (slow transmission to buy time)
Restrictions of public gatherings
School closure (effectiveness depends on where infection is spreading)
Voluntary home isolation of cases
Voluntary quarantine of contacts
Screening on entry to UK

Question 24

SARS CoV Info

Answer 24

2002
Animal origin/reservoir = bats
Intermediate hosts = civet cats
Incubation 2-7 days.
Case Fatality Rate: <24y: <1%. >50% in over 65s
No vaccine or specific treatment
Superspreading

Question 25

SARS S&S

Answer 25

Fever, cough, SOB, myalgia, diarrhoea
CXR shows pneumonia or respiratory distress syndrome

Question 26

MERS CoV

Answer 26

2012
Presents like SARS with severe acute respiratory disease
Bat origin. Intermediate host: camels
Superspreading

Question 27

Covid-19

Answer 27

Swiss cheese method of response (detect, test, trace, isolate, support)
Will become endemic but hasn’t yet.
Virus survives longer in higher humidity

Question 28

Pandemic response

Answer 28

Local, national & global surveillance
Epidemiological surveillance
Wastewater surveillance
Research (reinfections, durability of immunity, long covid, population behaviour)
Rapid evidence reviews
Vaccine efficacy studies

Question 29

Challenges & issues in Covid

Answer 29

Challenges:
misinformation & disinformation, covid deniers, antivax

Issues:
- health literacy
- epidemiological literacy (especially in politicians)
- risk perception

Question 30

Pneumonia causes

Answer 30

Respiratory viruses, bacterial and fungal

Typical pneumonias: Strep pneumonia, klebsiella, haemophilus influenza, staph a, group A strep, moraxella, pseudomonus

Atypical pneumonias:
mycoplasma, legionella pneumophilia (Legionnaires), chlamydia psitacci (bird exposure), aspergillus (mouldy hay)

Question 31

Classification of pneumonias

Answer 31

CAP (acute infection of lung tissue in a patient who has acquired it from the community or within 48 hours of the hospital admission)

HAP (acute infection of lung tissue in a non-intubated patient that develops after 48 hours of hospitalization)

HCAP (Healthcare associated): acute infection of lung tissue acquired from healthcare facilities such as nursing homes, dialysis centers, outpatient clinics, or a patient with a history of hospitalization within the past three months.

VAP (Ventilator associated): A type of nosocomial infection of lung tissue that usually develops 48 hours or longer after intubation for mechanical ventilation

Question 32

Pneumonia risk

Answer 32

Top 10 cause of death USA
Mortality from uncomplicated disease ~3%
Mortality from bacteraemic pneumonia 25%
1 million deaths globally pa in <5s
Risky even for young adults
5-10% pts admitted with CAP need intensive care
- Most common dangerous organisms = pneumoccocus (strep pneumonia) & legionella

Question 33

S. pneumonia (pneumococcus)

Answer 33

Common secondary infection
Lots of different serotypes
Causes meningitis, sepsis, invasive pneumococcal disease (severe pneumonia)

Also causes >50% of otitis media in children & milder pneumonia and bronchitis

Most common secondary bacterial infection of influenza

Question 34

Why do people get pneumonia

Answer 34

• defect in host immune defenses
• particularly virulent bacteria
• overwhelming inoculum
• Gains entry to lower respiratory tract: inhalation of aerosolised material or aspiration of upper respiratory tract resident flora

Question 35

Risk factors for pneumococcal disease

Answer 35

Reduced consciousness
Serious underlying disease
Factors impairing clearance of pulmonary pathogens (CF etc.)
Hypoxaemia
Acidosis
Alcohol
Toxic inhalations
pulmonary oedema
uraemia
malnutrition
steroids
immunosuppressives
viral infection
mechanical obstruction

Question 36

Importance of pneumonia prevention

Answer 36

High risk to elderly
High rate of CAP
Increasing resistance and multi resistant strains

Question 37

Pneumonia prevention strategies

Answer 37

Infection control in hospitals
Vaccination programmes (e.g. PCV13, PPV23)
Stop people getting things that make them susceptible – give flu vaccine and pneumonia vaccine to elderly etc.
Reduce occupational hazards (dust exposure –> wear masks etc.)
Nutrition

Question 38

Respiratory Syncytial Virus (RSV) about

Answer 38

Common cause of winter coughs & colds
Major cause of bronchiolitis in infants
Transmission: large droplets & secretions & fomites
Survives on hard surfaces: 4-7 hours
Incubation period: 3-5 days

Question 39

RSV epidemics

Answer 39

sharp winter peaks
Starts Nov/Dec lasts 4-5 months
Little variability in timing or magnitude

Question 40

At risk groups for RSV

Answer 40

Very young preterm babies (chronic lung disease of prematurity increases risk)

Very elderly

Question 41

Prevention/how to mitigate RSV Risk

(textbook exam Q)
(not just for RSV - similar measures for all respiratory viruses)

Answer 41

• Breast feeding
• Vaccination (passive vaccine) to newborn babies during RSV season
• Education & awareness - parents & elderly carers
• Hygiene measures (tissue in bin after blow nose, wash hands; cover mouth when cough)
• Stay away from grandchildren/grandparents when ill (especially flu)
• Don’t send sick kids to school
• Prewarning hospital/clinics so patients can be put in different waiting rooms
• Cohorting - separate infected & non infected area (for staff and pts)
• Isolate in hospital
• Clean rooms/environmental contamination
• Ventilation
• Treatment as prevention (if there is treatment)

Question 42

Legionella/Legionnaires Disease - where is it found

Answer 42

Environmental pathogen
Warm Stagnant water
Becomes a problem when water is aerosolised
- showers
- taps
- air conditioning (puddle of water behind AC units –> fan on)
- Jacuzzis
- Humidifiers

Also: cooling towers in factory plants –> water condenses on temperature gradient –> sumps of legionella –> windows –> spreads

Human = dead end host - can’t transmit to other humans

Question 43

Legionella prevention

Answer 43

Shock dosing up water towers with toxic substance that kills legionella
Test water supply if suspect domestic source
Maintain water temp >55 degs (building regulations)
Good plumbing techniques - no dead legs
Regular flushing and disinfection
Adequate cleaning and chlorination

Question 44

Legionella presentation & demographics

Answer 44

Incubation period: 2-10 days, typically 5-6 days

Flu like illness, muscle aches, tiredness, headache, dry cough, fever, pneumonia
Can progress to multi-organ failure

Question 45

At risk groups for legionella

Answer 45

More common in men
Over 50s
Heavy smokers

10-15% mortality

Question 46

Diagnosis and management of legionella

Answer 46

• detection of urinary antigen (false positive risk)
• culture from respiratory specimen = gold standard
• detection of legionella spp nucleic acid (e.g. by PCR) in LRT specimen

Management: Abx, supportive, intensive care

Question 47

PH investigation for legionella

Answer 47

Try to identify the source
10 day exposure history
- healthcare setting, travel, car wash, care, domestic, workplace,
- are there any other local cases (6km radius)

May carry out water & environmental sampling

Question 48

Surveillance of legionella

Answer 48

Not notifiable but Health Protection Team needs informing
Serious environmental issue
National enhanced surveillance scheme
European network monitors travel associated cases

Question 49

Legionella epidemiology UK

Answer 49

steadily increasing since 1980
~500 cases 2019
1/2 travel associated
1/2 community acquired

Question 50

Who enforces Legionella prevention & management England

Answer 50

Local authority environmental health officers OR health and safety executive