MIC1IEP Topic 12 Influenza 2016 [Compatibility Mode]

7/26/2019 MIC1IEP Topic 12 Influenza 2016 [Compatibility Mode]

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MIC1IEP

Topic 12 Influenza

26th May 2016

ANNA MORRIS

ROOM 310

THOMAS CHERRY BUILDING

PH: 9479 1501

[email protected]

Influenza : Orthomyxoviruses

Respiratory Tract Infection

Systemic rather than localised infection of

the respiratory tract and lungs

Transmission via droplets or fomites

Seasonal more common in winter

months & also in spring


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Influenza Virus

WHO: Annual epidemics cause 250,000

500,000 deaths worldwide

Vaccine preventable disease (Aust Govt -NNDSS)

71,528 cases Australia wide in 2015 ytd

67,757 cases in 2014

ad

campaigns


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Notifiable disease

Communicable disease

Required by law to be reported to the Health

Authorities

Infectious disease that is transmitted

readily from one individual to another

usually in normal everyday activities

Symptoms of Influenza


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How far do your droplets travel

in a sneeze?Brock Biology of microorganisms

100mph

30 feet = 9 metres

Myth busters

17 and 13 feet 4 5 metres

Either way, its a long way!!

Influenza types

Influenza type A

Humans, birds, animals

Epidemics and pandemics

Influenza type B

Humans

epidemics

Influenza type C

Mild respiratory infection

Not assoc with epidemics or pandemics


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Influenza A virusIcosahedral

Enveloped

Negative sense

ssRNA

~ 500 spikes or

projections

Hemagglutinin (HA) 4 x more than NA

Neuraminidase (NA)

Envelope carries Hemagglutinin and NeuraminidaseHemagglutinin assists with attachment

Neuraminidase assists in liberation of mature viruses from host cells

Influenza Envelope


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Replication cycle of Influenza A

virus

Influenza type A

Only A is subtyped

Typed according to surface glycoprotein

antigens

Hemagglutinin

Neuraminidase

18 H and 11 N recognized & named

accordingly


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The 2015 Southern Hemisphere influenza

season vaccine strains

A/California/7/2009 (H1N1)pdm09 - like virus

A/Switzerland/9715293/2013 (H3N2) - like virus

B/Phuket/3073/2013 like virus (Yamagata

lineage)

The Australian Influenza Vaccine Committee

(AIVC) selected influenza viruses for the

composition of the trivalent influenza vaccines. Therapeutic Goods Administration accepted the

recommendations of the AIVC.

Glycoproteins Haemagglutinin and

Neuraminidase

Type of H or N depending on which type of

each expresses

A/California/7/2009 (H1N1)pdm09 - like

virus

A/Switzerland/9715293/2013 (H3N2) - like

virus


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Resistance to reinfection??

Infected individuals will produce antibodies

to both H and N antigens

Lack of resistance to Flu from season to

season is due to mutation in surface

antigens

Mutation due to antigenic shift and drift Drift: small and constant

Shift: sudden and major

Only seen in Influenza type A

Results in pandemics due to new strain

Influenza : Five major pandemics

Spanish flu

1918

(H1N1)

20 50 million deaths

Asian FluH2N2

1957

2 million deaths

Hong Kong Flu

H3N2

1968

1 million deaths


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Influenza : Five major pandemics

Russian flu

1977

(H1N1)

17,000 deaths

Swine Flu

2009

H1N1

18,500 deathsSwine origin

Pandemic lasted until August 2010

Transmission

Droplet transmission

Inhalation

Fomites

Virus survival is high (many hours) outside

the body

Surfaces

Cloths, tissues

Infective period immediately prior to

signs and symptoms for up to 7 days after


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Infectious Droplets & Droplet

Nuclei Travel Lengths

Duck for cover!!

PathogenesisEntry via respiratory tract

Attachment to respiratory epithelial cells H spikes

Asymptomatic infection common

Mild infection possible

Cold-like infectionSymptoms appear 1 3 days following infection

Fever, chills, malaise, muscle pain

Due to release of cytokines from damaged cells & infiltrating leukocytes

Virus spread

Runny nose

Sore throat

Dry cough

Infection may increase in severity

Results in bronchitis or pneumonia


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PathogenesisRecovery

1 3 weeks

Unless progresses to more severe infection

Infective period starts before symptoms appear

Shedding of virus from this stage for a week

Death most common in:

elderly

Immunocompromised

2 0 bacterial infection most likely cause

Eg Pneumonia

Exacerbation of pre-existing chronic cardiac or respiratory illness

Predisposing factors

Impaired Immunity

Immunocompromised individuals

Age

< 5 - >65 years of agePregnancy

Aborigines & Torres Strait Islanders > 15

years

Medical condition

Heart disease, chronic lung disease

asthma, emphysema,


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Predisposing factors

Homelessness

Nursing home or long term care residents

Pre-existing chronic condition

Obesity, diabetes, alcoholism, kidney disease

Asthma patients who have frequent hospital

visits

Downs syndrome

Vaccination is recommended for high risk individuals

Universal influenza vaccine

Research being conducted into universal

vaccine

Aim is for vaccine to trigger immune

responses against conserved antigens These are viral protein targets that mutate

only slowly

And are also similar among many strains of

influenza viruses

Therefore can generate immune responses

that cross-react among virus strains


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Do I have a cold or the Flu??Flu is not the common cold!!

Flu is more severe

Cold symptoms last from two to a few days

flu lasts up to a week

Flu - high fever

Cold : usually only mild fever

Flu - Muscular pains and shivering attacks

flu usually starts with a dry sensation in the nose andthroat

Colds - runny nose

Flu symptoms onset rapid

Cold symptom onset gradual

ComplicationsMost common in immucompromised

Increases chances of complications and

risk of death

Primary Influenza pneumonia

Difficult breathing, cyanosis

20 bacterial pneumonia

Shortness of breath, green or yellow phlegm, chest

pains, fever

Inflammation of brain or heart

Often assoc with recovery process

Reyes syndrome


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Prevention

Annual immunization

Good personal hygiene

Cover nose and mouth when coughing or

sneezing

Dispose of tissue appropriately

Wash hands after cough or sneeze

Soap & water

Alcohol based hand sanitizer

Avoid touching eyes, nose & mouth

Stay home from work and school

Treatment

Bed & rest until body temp is in normal

range for 48 hours

Drink fluids to maintain normal urine

output

Paracetamol (+/or aspirin in adults) to

control fever, aches & pains

Antiviral treatment to reduce severity &

length of illness

Avoid further damage or challenge of

respiratory tract


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Mucocilliary escalator

Antiviral drugs

Relenza Zanamivir

Tamiflu oseltamivir

Used against both Types A & B Influenza

Act by inhibiting viral neuraminidase

Blocks release of new virus particles being

released from infected host cells

Recommended under severe infection or

in high risk individuals

Effective if treatment commences within

48 hours of symptoms appearing


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Identification/DiagnosisReverse transcription polymerase chain

reaction (RT-PCR) (1 6 hours)

RIDT Rapid Influenza Diagnostic test

Used for Influenza types A & B although not

can distinguish (


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Influenza vaccine manufacture

Avian Flu Influenza type A

Bird Flu

Human infection after virus crosses

species barrier

Usually results after contact with infected

poultry or environments

Human to human contact is rare but does

occur

Different types have been isolated


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H5NI (HPAI Highly pathogenic avian

influenza)

H5N1 causes infection in man and

animals other than poultry, eg domestic

cats and dogs

Highly pathogenic

high incidence of disease & death

wild birds and domestic poultry

HPAI H5N1

first isolated in 1996

farmed goose

Guandong province, China

H5NI (HPAI Highly

pathogenic avian influenza)Followed by outbreaks in 1997

poultry farms & live animal markets

18 humans infected & 6 deaths

Increasingly assoc with infection in

chickens

Culling of commercial poultry flocks

Hong Kong

Effective

Outbreaks in 2003 resulted in infection in over

60 countries


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H5NI (HPAI Highly pathogenic avian

influenza)

Re-emerged in 2003 in birds

Death of 100s of millions of birds

Disease

culling

Re-emerged in humans

630 cases

375 deaths

By June 2013

Infection is with direct contact with birds

rather than human to human transmission


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ReferencesMicrobiology and Infection Control for Health

Professionals. Chapter 19, 6th Ed, Lee &

Bishop.

Chapter 8, Brock Biology of Microorganisms,

14th Ed, 2015

Microbiology and Infection control for Health

professionals. Chapter 19 , Lee & Bishop.

http://www.fda.gov/BiologicsBloodVaccines/ScienceResearch/ucm353397.htm

http://www.medical-supplies-equipment-

company.com/flu-transmission-and-flu-

prevention-576.htm

References

http://www.rapidreferenceinfluenza.com/ch

apter/B978-0-7234-3433-7.50009-

8/aim/influenza-virus-structure

http://www.virology.ws/2009/04/30/structure-of-influenza-virus/

http://www.betterhealth.vic.gov.au/bhcv2/b

hcarticles.nsf/pages/Flu_influenza


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Learning ObjectivesAt completion of this lecture students should

be familiar with:

Some of the basic characteristics & clinicalfeatures of the Influenza virus and the Fludisease

The mode of transmission, pathogenesis,symptoms, treatment and prevention ofInfluenza

Documents

MIC1IEP Topic 12 Influenza 2016 [Compatibility Mode]