http://www.uct.ac.za/deps/mmi/stannard/fluvirus.html
Diagnosis and Management
of Influenza
A/Prof. Michael Nissen
Director of Infectious Diseases & Clinical Microbiologist
Royal Children’s Hospital-Brisbane
Queensland Children’s Medical Research Institute
University of Queensland
Herston, Qld. Australia
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Overview
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http://www.uct.ac.za/depts/mmi/stannard/fluvirus.html
• Influenza infection
• Diagnosis of influenza
– Clinical
– Laboratory
• Management of influenza
– Infection Control
– Antivirals
– [Vaccines]
2
Influenza
http://www.uq.edu.au/vdu/VDUInfluenza.htm
Orthomyxoviridae
-ssRNA virus [8 segments], 14kb, enveloped, 80-120nm
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Influenza
• Acute respiratory and systemic disease
caused by infection with influenza type A,
type B and influenza type C viruses.
• Influenza A viruses sub grouped on the basis
of their surface haemagglutinin (H) &
neuraminidase (N) glycoproteins.
• Influenza A subtypes currently circulating
most widely in humans are A (H1N1) &
A(H3N2).
• Aquatic birds are primary reservoir for
influenza A viruses but also circulate among
other animals including pigs, horses & seals.
• Humans are the primary reservoir for
influenza B viruses.
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Influenza type A
Subtype variation:
• 16 different haemagglutinin(HA) types: H1-16
• 9 different neuraminidase (NA) types: N1-9
• Recombination of HA and NA possible.
H1N2
H2N1
H2N2
H2N9
H3N2
H3N3
H3N6
H3N8
H4N6
H4N8
H5N1
H5N3
H6N1
H6N2
H6N9
H7N2
H7N3
H7N7
H8N4
H9N2
H10N3
H11N1
H11N8
H11N9
H12N4
H13N6
H14N1
H15N2
Strain variation:
• Point mutations create variation within subtypes
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Influenza
• Influenza A and B viruses cause seasonal
epidemics with winter peaks in temperate
zones and year-round circulation in the
tropics with rainy season and dry season
peaks in activity.
• A & B viruses continually evolve by
accumulation of mutations leading to
antigenic drift of the H and N
glycoproteins.
• A viruses also evolve by reassortment
leading to novel influenza A viruses and
potential influenza pandemics if the novel
virus spreads in a sustained manner
through largely susceptible populations.
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Jan-05
Su
Au
Wi
Sp
Jan-08
Feb-08
Mar-08
Apr-08
May-08
Jun-08
Jul-08
Aug-08
Sep-08
Oct-08
Nov-08
Dec-08
Sp
Nov-…
Wi
Sep-07
Au
Jul-07
2006
May-…
Su
Mar-…
Sp
Dec-05
Jan-06
Feb-06
Mar-06
Apr-06
May-06
Jun-06
Jul-06
Aug-06
Sep-06
Oct-06
Nov-06
Dec-06
Jan-07
Nov-05
Wi
Oct-05
Sep-05
Aug-05
Au
Jul-05
Jun-05
May-05
Su
Apr-05
Mar-05
12.0
10.0
8.0
6.0
4.0
2.0
0.0
Feb-05
% Positive of Total Tested
2005
2007
2008
30.0
25.0
Influenza A
20.0
15.0
10.0
5.0
0.0
Su
Au
Wi
Sp
S
Influenza B
Reassortment of Influenza A strains
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Influenza
• The spectrum of influenza infection
is wide:
– nonfebrile, mild upper respiratory tract
illness,
– febrile influenza-like illness (ILI)
– severe & fatal complications.
• Greatest burden of illness usually
occurs among children.
• Greatest severe disease
[hospitalization & death]:
– underlying medical conditions, infantsyoung children & elderly.
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Fatal H1N1 Viral Pneumonia
10
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Clinical diagnosis of Influenza
• Influenza Like Illness [ILI]
– Fever, cough, sore throat, rhinorrhea,
headache, myalgia & malaise
– NO shortness of breath, NO dyspnoea
– Some or all symptoms
– GIT symptoms without dehydration-especially
children
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45.0
40.0
2005
2006
Percentage positive
35.0
30.0
25.0
20.0
15.0
IA
10.0
IB
5.0
PIV1
0.0
PIV 2
Month
Month
summer
autumn
winter
PIV 3
spring
summer
autumn
winter
spring
ADV
30.0
Percentage positive
25.0
RSV
2008
2007
HMPV
20.0
15.0
10.0
5.0
0.0
Month
Month
Diagnosis of Influenza in Adults
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Adults risk factors for influenza
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When to test for Influenza in Adults
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Influenza in children
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Childhood Influenza Risk Factors
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Diagnostic tests for Influenza
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Specimen collection
Nasopharyngeal aspirates are collected from patients
and are still considered the specimen of choice
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Diagnostic settings for Influenza
WHO 2010
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Number of Samples
140000
14,000
120000
12,000
10,000
100000
8,000
80000
6,000
60000
4,000
40000
2,000
20000
Increase = 12 to 43% per year
00
2000
2001
2002
2003
2004
2005
2006
2007
2008
The introduction of real-time PCR for respiratory viruses has
provided significant additional benefits to our organisation
•
•
•
•
•
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Improved diagnosis (greater sensitivity & specificity)
Improved turn around times for results (3 – 24 hours)
Reduced costs; particularly labour component
Better patient care (positive diagnosis/limit use of antibiotics)
Changed barrier nursing practice
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Until April 2009, the influenza A testing protocol utilised primers and
probes targeting the gene coding for the matrix protein*
Assay was validated against:
H1N1, H2N1, H2N2, H3N2, H4N6, H5N1(3)*, H5N3,H6N1, H7N7, H9N2, H11N1
* Vietnamese (2); Indonesian (1) strains
Specimens for clinical diagnosis of Influenza are tested by the duplex
real-time PCR assay for INF A & INF B
Any Influenza A-positive samples are then screened further with a
second H5N1-specific assay targeting the haemagglutinin gene.
All positive specimens are forwarded to the QH Public Health Virology
laboratory for Influenza typing and confirmation of any H5N1 result
All positive isolates are forwarded to the WHO Collaborating Centre for
Reference and Research on Influenza, Melbourne.
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*Whiley et al. Diagnostic Microbiology and Infectious Disease 53 (2005) 335–337
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QPID matrix assay
H3N2
H5N1
H5N3
H7N7
H9N2
Previous matrix assay
H3N2
H5N1
H5N3
H7N7
H9N2
The Australian National Incident Room (NIR) was notified by
WHO on 24 April 2009 of outbreaks in Mexico & USA of a
novel strain of A/H1N1 influenza (Swine flu).

H1N1 influenza 09 was a novel influenza A virus infecting humans.

H1N1 influenza 09 appeared to be formed through reassortment of
human and swine-origin influenza strains, creating a virus against which
humans have little or no immunity.
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Friday
24 April
Monday
27 April
Assays
designed
Wednesday
6 May
Assay validated
Transferred to PQ
Publication
submitted
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Friday
24 April
Monday
27 April
Assays
designed
Wednesday
6 May
Assay validated
Transferred to PQ
Thursday (night)
7 May
PQ Detected
First positive
case in
Australia
Saturday
9 May
Positive result
confirmed by
WHO, Melbourne
Publication
submitted
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Respiratory virus PCR Requests
2006 – 2009 at PQ Central
37,263
10832
H1N1 requests
27/04 – 15/09
Respiratory virus
PCR requests
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Management of Influenza
• Infection Control
• Antivirals
• [Vaccines]
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Infection Control
•Appropriate infection control measures
(Standard plus Droplet Precautions)
should be adhered to at all times.
•Whenever performing high risk
aerosol-generating procedures (e.g.
bronchoscopy or any procedure involving
aspiration of the respiratory tract)
use a particulate respirator (N95)
• Eye protection, gowns, and gloves and
carry out the procedure in an adequately
ventilated room, either naturally or
mechanically.
•Don’t forget handwashing and cough
etiquette!
WHO 2009
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Infection Control
•The duration of isolation precautions for
hospitalized patients with influenza:
•7 days after onset of illness or
•24 hours after the resolution of fever
and respiratory symptoms, whichever
is longer, while a patient is in a healthcare facility.
•For prolonged illness with complications
(i.e. pneumonia), control measures should
be used during the duration of acute illness
(i.e. until the patient has improved
clinically).
•Special attention is needed in caring for
immunosuppressed patients who may
shed virus for a longer time period and are
also at increased risk for development of
antiviral-resistant virus
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Antiviral medications
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Antivirals for Influenza
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Mode of action
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Neuramidase inhibitors
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Oseltamivir
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Oseltamivir
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Oseltamivir
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Antiviral medications
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Conclusion
• Influenza diagnosis is dependant on clinical
findings supported by known epidemiology
& laboratory identification during
epidemics and pandemics.
• Molecular techniques such as PCR have
revolutionised approach to influenza
epidemiology, diagnosis and treatment.
• Antivirals assist in controlling complications
of influenza in seasonal epidemics and
pandemics.
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Thank you for your attention
Brisbane-Australia
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Royal Children’s Hospital-Brisbane
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Diagnostic tests for Influenza
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RIDT Mode of action
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Rapid Influenza Diagnostic Tests
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