Health Talk on Bird Flu for Airport Community

21 October 2005

Speaker: Dr John Simon

What’s All The Fuss About Bird Flu?

John SimonHonorary Professor

Dept. of Microbiology

University of Hong Kong

Avian influenza H5N1

“The Enemy”

Neuraminidase HaemagglutininBirds N 1-9 H 1-16Human N1-2 H1-3

Human influenza epidemics

Influenza Pandemics in the 20th Century

• In 1957 ‘Asian’ influenza caused more than 1 million deaths

• In 1968 ‘Hong Kong’ influenza caused more than 1 million deaths

• In 1918 ‘Spanish’ influenza caused

40 million deaths

Influenza Pandemics in the 20th Century

A Pandemic today is likely to:• Spread rapidly• Affect 15-30% of the population of any one

country within weeks• Span the globe in months (like 1968 pandemic)• Have greater socio-economic impact• Impact supply chains• Not be stopped the way that SARS was.

Bird Flu

• Due to a Type A Influenza

• H5N1, H9N2, H7N7, H5N2, H7N1

• H5N1: ‘Highly Pathogenic Avian Influenza’

H5N1 In Poultry

• South Africa 1961

• Hong Kong 1997

• China, South Korea, Japan, Vietnam, Thailand, Camodia, Laos, Pakistan, Indonesia, Malaysia 2003-2004

• Kazakhstan, Russia (Urals, Siberia) Mongolia, Romania, Turkey 2005

H5N1 in Wild Birds

• Wild Ducks Have No Symptoms

• Asymptomatic Carriers

• Bird-fall in Qinghai

• Migratory Birds Spread It

• Now a Zoonosis

We Had Our Chance

• Culling Stopped It In HK in 1997

• Universal Culling in Vietnam, Thailand & China May Have Stopped It

• Now It Is A Zoonosis It Is Here to Stay

Surveillance of H5N1 viruses in live poultry markets in mainland China

Li et al Nature 2004; 430: 209-213

• I Don’t Know What Will Happen Except To Tell You “We’re Screwed”– Dr Michael Osterholm, Director Center for ID

Research & Policy June 2005.

Human H5N1 cases and deaths since Jan 2004

Cases DeathsVietnam 91 41Thailand 17 12Cambodia 4 4Indonesia 5 3Total 117 60

The tip of the iceberg

Features of H5N1 in Humans

• Male/Female Ratio 2/3

• Age Range 4 Months to 69

• Median Age 19. Average Age 24

• Case Fatality Rate (CFR) 52%

• CFR Last 10 Months 39%

Transmission To Humans

• Nasal, Salivary & Fecal Excretions

• Contact With Contaminated Surfaces

• Inhalation of Dried Out Feces

• Eating Undercooked Viremic Birds

• Drinking Ducks’ Blood

Human-To-Human Transmission

• Currently Inefficient

• Only One Likely Case (Thailand 2003)

• Requires Very Close Contact

• Efficent Transmission Pandemic

• Requires Virus Mutation

The origin of influenza pandemics

How may a H5N1 pandemic virus arise?

It happened with SARS

It happened with the 1918 “Spanish flu”

Will A Pandemic Occur?

• Yes: As They Have Occurred Over Many Centuries Past

• Can’t Say When: Next Month, Next Year?

• Can’t Say If It Will Be H5N1 or Another

Why it is likely that H5N1 will be the

next pandemic virus?

• Endemic across a wide geographical area

• Repeated (thousands) opportunities for infecting humans

• Repeated inter-species transmission to mammals and to humans

• Potential for reassortment in pigs or in humans

So What’s The Fuss

• A pandemic virus could be due to recombination (reassortment) or gradual mutation with a direct jump from birds to humans. The latter is likely to be more severe than the former

• H5N1 mutation allowing efficient human-to-human transmission may not be less severe a clinical illness in humans than it currently is and might parallel the severity seen in the 1918 pandemic

Incubation

• Unknown. Probably Less Than 1 Week

• “Ordinary Flu” 1-4 Days

Clinical Course

• “Ordinary Flu”: Fever, Cough, Muscle Pain, Headache, Sore Throat

• “Cytokine Storm”

• Pneumonia, Respiratory Distress

• Multi-organ Failure, DIC

Treatment

• Supportive Therapy

• Mechanical Ventilators

• Antiviral Drugs (Relenza or Tamiflu)

• Relenza: Inhalation. More difficult to use but as effective as Tamiflu

Tamiflu

• Must start within first 48 hours

• Preferably within first 24 hours

• Dose 1 capsule (75mg) twice daily 5 days

• Suspension form available for children

• Active against all types of influenza A

• Some partial resistance H5N1 noted

• No guarantee it will be effective !

Tamiflu as a Prophylaxis

• 1 Capsule Daily for– Contacts of known cases– Those involved in culling– In pandemic situations? How long

Tamiflu

• Not available: Indonesia, India, Pakistan

• Cost for a packet of 10 capsules varies

• US$25-60

Vaccine

• Sanofi-pasteur trials successful

• Probably ineffective against mutant

• Will need to rapidly make new vaccine

• However current process is very slow

• Will take 6 months to develop

• You are unlikely to get the vaccine

• Slow to make. Only small quantities

Effects of a Pandemic

• Total disruption of travel and business

• International borders will close

• Schools, cinemas, restaurants close

• Hospitals cannot cope

• Shortage of ventilators

• Up to ?? 50 million may die

• Friends, colleagues, family will die

What Needs to be Done?

• Control the outbreak in poultry

• Early warning of human-to-human spread

• Pandemic preparedness and logistics

• Antivirals

• Vaccines: logistics of production

Problems with Control in Poultry

Backyard flocks

Problems with Control in Poultry

“wandering ducks” and “Trojan horses”

Problems with Control in Poultry

Live poultry markets

Can We Stop A Pandemic

• Theoretically Yes (“Nature”, “Science”)

• Need to Identify Early Clusters

• Social Isolation

• Blanket Tamiflu

• Reduce Ro

• In My Opinion “No!”

So What Shall We Do?

• Prepare for a Pandemic

• Governments to Stockpile Tamiflu

• Individuals to Purchase Own Supplies

• Corporations to Make Contingencies

• Get “Ordinary Flu” Vaccination

• Educate

Transmission of influenza viruses

5

• Infectious from 24-48 hrs before symptoms• Infectious until 7-8 days after onset of disease, or longer• Asymptomatic infection may transmit

Large droplets: short range?? Aerosols: long range

Contaminated hands?Surfaces?

Possible interventions:

• Hand hygiene: facilities available in workplace • Masks

– Recommended for those with symptoms– For those in “person-contact” occupations– Education on how to use and dispose of a mask. – Doubtful benefit for general community

• ‘Increase “social distance”– Closure of schools and public places– Stop public gathering – Curtailing non-essential activities and services– Curtail non-essential domestic travel

Reduction of other viral respiratory infections during SARS

Websites

• www.cdc.gov/flu/avian/index.htm

• www.who.int/csr/disease/avian_influenza/en/

• www.info.gov.hk/dh/diseases/influenza/influenza.htm

• www.wpro.who.int/avian/

Summary

• An H5N1 Pandemic Will Occur

• Many Millions Will Die

• Do Not Expect To Get A Vaccine

• Tamiflu or Relenza May Work. Get It Now!

Oh! It’s just the flu

Acknowledgment

• Professor Malik PeirisUniversity of Hong Kongfor use of some of his slides

Response MeasuresAlert Response

LevelSerious

Response LevelEmergency

Response LevelOwner

Influenza vaccination See Notes * HRD

Temperature screening, health declaration TBU

Staff education HRD / SSEPS / CS

Airport staff temperature monitoring All BU / SU

Encourage restaurants to provide serving utensils RAB

Maintain close contact with Department of Health SSEPS / TBU

Maintain an adequate supply of personal protection equipment, i.e. face masks, disinfectants, etc

HRD/TSP

Step up cleaning and disinfection of public installations TBU

Provide adequate facilities and cleaning materials for hand-washing

TBU

Case Reporting All BU / SU

Step up maintenance on indoor ventilation system TSP

Adequate equipment for protecting frontline staff TSP

Restrict Access to Critical Operational Control Centers TBU / ABU / TSP / MIT

Staggered work deployment TBU / ABU / TSP / MIT

Minimize large meetings All BU / SU*To lower the possibility of misdiagnosing cold and flu with avian flu