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3rd Year Infection > Influenza > Flashcards

Influenza Flashcards

1
Q

When are the influenza months?

A

Dec - Feb (North)

Jun - Aug (South)

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2
Q

When do more severe influenza epidemics take place?

A

Every 11 years - sunspots

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3
Q

What type of virus is influenza?

A

RNA virus - Orthomyxoviridae

A, B, C

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4
Q

Which influenza groups affect humans?

A

IfB

IfC

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5
Q

Which influenza surface proteins affect humans?

A

Haemagglutinin (H) 18 types

Neuraminidase (N) 11 types

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6
Q

What is the role of Haemagglutinin?

A

Facilitates viral attachment and host cell entry

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7
Q

What is the role of Neuraminidase?

A

Enables new virion to be released from the host cell

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8
Q

What is antigenic drift?

A

Small, on-going point mutations in the genes coding for antibody binding-sites

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9
Q

What is the effect of antigenic drift?

A

Change the antigenic properties, so immune system cant combat it
(reduces immunity/vaccine effectiveness)

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10
Q

What is antigenic shift?

A

Abrupt change in virus - new H/N combinations

2 or more strains combine to form new subtype

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11
Q

What is the effect of antigenic shift?

A

Jumping from species - species
Can combine to form
Reassortment of virus gene segments
Can lead to pandemics

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12
Q

What virus was implicated in the 2009/10 pandemic?

A

H1N1

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13
Q

How does pandemic flu differ from seasonal flu?

A

Pandemic:
Sporadic
25%+ population
More serious

Seasonal:
Every winter
10-15% population
Unpleasant

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14
Q

What are the requires for a pandemic?

A

Human pathogenicity
Antigenic shift = susceptible population
Efficient person-person transmission

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15
Q

Which Avian flu strains effect humans?

A

H5N1

H7N9

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16
Q

How is Avian flu spread?

A

Direct contact with infected birds

Human-human

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17
Q

What is the fatality rate of Avian flu?

A

H5N1 - 60%

H7N9 - 36%

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18
Q

Where is avian flu still present?

A

H5N1 - Egypt

H7N9 - China

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19
Q

What are the clinical features of influenza?

A 
2-4 day incubation
Abrupt 41C fever 3 days
2 or more of:
Cough
Sore throat
Myalgia
Headache
Malaise
20
Q

What is Influenza-like illness?

A

Fever >38C AND
Cough
Onset within last days

21
Q

How is influenza transmitted?

A

Airborne - droplets >5um

Contact

22
Q

What is virus shedding?

A

First 4 days of illness

longer in children/immunocompromised

23
Q

How long is virus survival?

A

24-48hrs on non-porous surfaces

8-12hrs on porous surfaces

24
Q

What are the risk factors for complicated influenza?

A

Neurological, hepatic, renal, pulmonary and chronic cardiac disease
Diabetes mellitus
Severe immunosuppression
Age over 65 years
Pregnancy (+ up to two weeks post partum)
Children under 6 months of age
Morbid obesity (BMI ≥40)

25
Q

What are the common complications of influenza?

A

Acute Bronchitis

Secondary bacterial pneumonia

26
Q

How does Secondary bacterial pneumonia present?

A

4-5 days post-flu
S. pneumoniae
Staph aureus
H. influenzae

27
Q

What are the less common respiratory complications of influenza?

A

Primary viral pneumonia

28
Q

What are the less common cardiac complications of influenza?

A

Myocarditis/pericarditis

29
Q

What are the less common CNS complications of influenza?

A

Transverse myelitis/Guillain-Barre

Myositis & Myoglobulinaemia

30
Q

How does primary viral pneumonia present?

A

Common in H5N1
Rapid respiratory failure (48hrs)
Mortality >40%

31
Q

What is encephalitis lethargica?

A

Post-influenza sequelae

32
Q

How does encephalitis lethargica present?

A 
Fever
Headache
External ophthalmoplegia
Lethargy
Sleep reversal
Postencephalitic Parkinsonism
25% mortality
33
Q

How is influenza diagnosed?

A 
Viral nose/throat swabs
PCR
Chest x-ray (pneumonitis/ia)
Blood culture
Pulse oximetry 
Respiratory rate
U+E, FBC, CRP
34
Q

What is the function of CRP monitoring in influenza?

A

Monitoring pneumonia recovery

CRP should halve in 4 days

35
Q

When is an urgent CXR indicated in pneumonia?

A

Flu like symptoms and fever for >4 days

36
Q

Which severity assessment is used for pneumonia?

A

CURB-65

37
Q

What does CURB65 stand for?

A 
Confusion
Urea (>7mmol/l)
Resp rate (>30)
Blood pressure (<90sys, <60dia)
>65y/o
38
Q

Which medications are used for influenza?

A

Neuraminidase Inhibitors (antivirals)
Within 48hrs
Oseltamivir (Tamiflu)
Zanamivir (Relenza)

39
Q

Which medications are used for influenza? (Hard)

A 
Neuraminidase Inhibitors within 48hrs
Oseltamivir (Tamiflu)
Dose - 75mg every 12hrs 5 days
Zanamivir (Relenza)
Dose - 10mg inhaled daily up to 10 days
40
Q

What side effects are associated with Oseltamivir?

A 
Nausea + Vomiting
Abdominal pain
Diarrhoea 
Headache
Caution in renal failure
41
Q

How is complicated influenza managed?

A

Oseltamivir (oral)

Zanamivir if resistant/poor response

42
Q

What are the less commonly used antivirals in influenza?

A

Peramivir - IV (uncomplicated)
Flavipiravir - oral
Baloxavir Marboxil

43
Q

How is antiviral therapy managed in pregnancy?

A

Oseltamivir

44
Q

How is antiviral therapy managed in breastfeeding?

A

Oral Oseltamivir

45
Q

When does an individual become non-infectious?

A

24hrs after last symptoms
or
When anti-viral therapy is completed
(in immunocompetent adult)

46
Q

How can healthcare staff protect themselves from flu in patients on nebuliser/NIV?

A

Face fit respirator mask

3rd Year Infection (16 decks)

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