Influenza Dr Bhakti Vasant Public Health Physician Metro South Public Health Unit - Brisbane South PHN
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Metro South Public Health Unit
Influenza
Dr Bhakti Vasant
Source of image: CDC. Influenza
Public Health Physician images. Available from URL:
https://www.cdc.gov/flu/images/h1
Metro South Public Health Unit n1/3D_Influenza/3D_Influenza_bl
ue_no_key_full_lrg2.jpg
Outline
• Background
• Epidemiology
• At risk groups
• Symptoms & complications
• Transmission
• Diagnosis
Source of image: Clancy S.
• Prevention Genetics of the influenza virus.
Nature Education 2008; 1(1):
• Treatment 83
Background • Acute resp illness • Recognised since 16th century • Spreads rapidly in communities in outbreaks • Caused by a virus (A, B, C or D) • Seasonal / epidemic (antigenic drift) • Pandemic (antigenic shift) Source: Paules. Influenza. The Lancet 2017; 390: 697–708 , World Health Organization. Influenza (seasonal) fact sheet. Available from URL: http://www.who.int/mediacentre/factsheets/fs211/en/
Background: the viruses
Influenza A • Classified as per haemagluttinin (HA) and
neuraminidase (NA)
• Includes H1N1 and H3N2
• Known to have caused pandemics
Influenza B • Not classified into subtypes
• Divided into B/Yamagata or B/Victoria
lineage
Influenza C • Causes mild infections
Influenza D • Not known to cause illness in humans
Source: World Health Organization. Influenza (seasonal) fact sheet. Available
from URL: http://www.who.int/mediacentre/factsheets/fs211/en/
Number of laboratory-confirmed influenza
notifications, Australia 2001 - 2017
300000
250000
Number of notifications
200000
150000
100000
50000
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Year
Source of data: National Notifiable Disease Surveillance System. Available from URL:
http://www9.health.gov.au/cda/source/rpt_2.cfm
Impact of 2017 flu season: Australia
(data from 1 Jan until 22 Nov 2017)
• High rate of GP consultations
• Sentinel GP ILI consultations 14.8 per 1000 consults
vs prev 5yr average: 10.3 per 1000 consults
• Increased hospitalisations
• Admissions to sentinel hospitals were 2.3 times the
prev 5yr average
• Higher number of deaths
• Deaths in 2017 (to 22 Nov 17): 745
• Prev 5 yr average: 176
• Median age of death: 86 years (range 3 to 107y)
• 91% of deaths in people age 65y or older
Source: Australian Government Department of Health. 2017 Influenza season in Australia. Source:
http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-surveil-ozflu-flucurr.htm/$File/2017-season-summary-22112017.pdfLaboratory-confirmed influenza notifications in
Queensland by week of onset, 1 Jan 2012 to 22 Oct 2017
Source of data: Queensland Health Statewide Weekly Influenza Surveillance Report. Available from URL:
https://www.health.qld.gov.au/__data/assets/pdf_file/0034/656494/influenza-qld-2017.pdfQueensland influenza notifications and
hospitalisations, 2016 (full yr) and 2017 (1 Jan – 22 Oct)
2016 2017
(partial yr)
All influenza notifications 23,261 53,451
Influenza A 21,415 35,962
A(H1N1)pdm09 833 538
A/H3N2 2,214 2,532
Subtype unavailable 18,368 35,962
Influenza B 1,846 17,489
Type unavailable 0 0
Influenza hospitalisations (public) 3,197 5,710
Intensive care admissions 402 678
Source: Queensland Health. Statewide weekly surveillance reports. Available from URL: https://www.health.qld.gov.au/clinical-
practice/guidelines-procedures/diseases-infection/surveillance/reports/fluLaboratory confirmed influenza admissions to
Queensland public hospitals by age group and gender,
1 Jan to 22 Oct 2017
Source of data: Queensland Health Statewide Weekly Influenza Surveillance Report. Available from URL: https://www.health.qld.gov.au/__data/assets/pdf_file/0034/656494/influenza-qld-2017.pdfMetro South region: lab-confirmed influenza
according to year
Year Number of cases
2013 1,402
2014 4,434
2015 7,395
2016 5,783
2017 13,163
Source of data: Queensland Health. Notifiable Conditions Annual Reporting.
Available from URL: https://www.health.qld.gov.au/clinical-practice/guidelines-
procedures/diseases-infection/surveillance/reports/notifiable/annualAt risk groups
• Age
• Increased risk of death in ≥65y of age
• Increased risk of hospitalisation inSigns and symptoms
• Fever
• May be absent in the elderly
• Respiratory
• Usually non-productive cough
• Sore throat
• Rhinorrhoea
• Constitutional
• Headache, myalgia, chills, fatigue and anorexia
• Gastrointestinal
• Less common (usually in children)
Source: Bresee JS. Inactivated Influenza Vaccines. From Plotkin’s Vaccines, 7th edition, Elsevier
2018Signs and symptoms: influenza in the elderly • Fever may be absent • May have anorexia, lassitude or confusion Source of text: Bresee JS. Inactivated Influenza Vaccines. From Plotkin’s Vaccines, 7th edition, Elsevier 2018, source of image: Daily Mail (Australia). Available from: http://www.dailymail.co.uk/health/article-3552181/Why-flu-deadly-elderly- Older-people-s-immune-systems-fail-detect-infection-t-mount-response.html
Signs and symptoms: case definition of influenza-like illness (ILI) in RACF Source: Communicable Diseases Network Australia. Guidelines for the prevention, control and public health management of influenza outbreaks in residential care facilities in Australia. CDNA 2017. Available from http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_G uidelines.pdf
Symptoms and complications Source: Ghebrehewet. The BMJ 2016; 355:i6258, doi: 10.1136/bmj.i6258
Transmission is efficient
• Aerosol
• Generated from coughing or sneezing
• Can remain airborne for minutes to hours
• Detected in the air from patients’ rooms
• Droplet
• Also generated from coughing or sneezing
• Contact transmission
• The virus is infectious on hands for a short period
• Can remain infectious on non-porous
environmental surfaces for up to 48 hours
Source: Paules C. Influenza. The Lancet 2017; 390: 697–708Transmission of seasonal influenza • A person with seasonal influenza will infect, on average, 1.28 other people. • [Of 57 studies, the median R0 = 1.28 (interquartile range: 1.19–1.37)] Source of text: Biggerstaff M. BMC Infectious Diseases 2014;14:480 https://doi.org/10.1186/1471-2334-14-480, source of image: https://sites.psu.edu/siowfa15/2015/09/07/d oes-your-heart-really-stop/
Incubation period and infectious period
• Average incubation period = 2 days (range 1–4
days)
• Infectious period = 1 day before illness onset +
Viral shedding is greatest 3–5 days post onset
(Can be longer in children and severely
immunocompromised people)
Source: Communicable Diseases Network Australia. Guidelines for the prevention, control and public health
management of influenza outbreaks in residential care facilities in Australia. CDNA 2017. Available from
http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_G
uidelines.pdfDiagnosis • Nucleic Acid Amplification Test (NAAT) • GeneXpert® • Point of Care Testing Source: Communicable Diseases Network Australia. Guidelines for the prevention, control and public health management of influenza outbreaks in residential care facilities in Australia. CDNA 2017. Available from http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_G uidelines.pdf
Prevention Source of image: CDC. Seasonal influenza (flu) preventive steps. Available from URL: https://www.cdc.gov/flu/consumer/prevention.htm
Prevention
• Influenza vaccination
• Most important step in preventing influenza infection
• Even with reduced vaccine effectiveness, may prevent some
flu illness, medical visits and hospitalisations
• Important for elderly residents and RACF staff
• Infection control and cough etiquette
• Ill staff should be excluded for at least 5 days after symptom
onset or until they are symptom free, whichever is longer
• Antiviral medications
• Role in treatment and prophylaxis in aged care
Source: CDC. Seasonal influenza (flu) preventive steps. Available from URL: https://www.cdc.gov/flu/consumer/prevention.htm , Communicable
Diseases Network Australia. Guidelines for the prevention, control and public health management of influenza outbreaks in residential care
facilities in Australia. CDNA 2017. Available from
http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_Guidelines.pdfTreatment
• Healthy individuals
• Supportive: adequate fluids, antipyretics, rest,
exclusion from work for at least 5 days from
symptom onset
• Antivirals are recommended for the following
groups:
• Patients at high risk of developing severe or
complicated disease, including the elderly
• Patients with severe or progressive clinical illness
Source: Ghebrehewet. The BMJ 2016; 355:i6258, doi: 10.1136/bmj.i6258, World Health Organization.
Influenza (seasonal) fact sheet. Available from URL:
http://www.who.int/mediacentre/factsheets/fs211/en/Antiviral prophylaxis • “The widespread use of antivirals in institutions that house residents at high risk of severe disease and death from influenza is supported by observational cohort studies and one randomised controlled trial.” • Antivirals are NOT a substitute other OB control measures! • Need to commence promptly for all targeted residents & staff (ideally within 24 hrs) • Consider renal function → Dose adjustment • = Pre-planning & preparedness Source: Communicable Diseases Network Australia. Guidelines for the prevention, control and public health management of influenza outbreaks in residential care facilities in Australia. CDNA 2017. Available from http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_G uidelines.pdf
Antiviral prophylaxis
• For ALL asymptomatic residents
• For ALL un-vaccinated staff
• Incomplete coverage → Effectiveness↓
• Should be organised within 24 hrs
• Considerations for decision to use
• Current epidemiology
• Outbreak characteristics (attack rate, morbidity …)
• Outbreak progress (eg. time since 1st case)
• Facility characteristics
• Clinical resources (GP No. & engagement, staff)
• Timeliness of oseltamivir supply
Source: Communicable Diseases Network Australia. Guidelines for the prevention, control and public health
management of influenza outbreaks in residential care facilities in Australia. CDNA 2017. Available from
http://www.health.gov.au/internet/main/publishing.nsf/Content/27BE697A7FBF5AB5CA257BF0001D3AC8/$File/RCF_G
uidelines.pdfConclusion • Influenza is associated with seasonal outbreaks in the winter months. • Elderly people are at risk of severe disease and complications. • Elderly people may not have classical flu symptoms. • Vaccination, infection control and antiviral medication have a role in preventing influenza.
Acknowledgements • Metro South Public Health Unit • Gayle Pollard • Bonnie Macfarlane • Kari Jarvinen • Communicable Diseases Branch, Queensland Health
Contact email: Bhakti.Vasant@health.qld.gov.au Source of image: http://www.powerpointhintergrund.com/uploads/thank-you-background-powerpoint-22.jpeg
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