Influenza 101

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Influenza 101

• Nebraska Public Health Laboratory

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Influenza The Virus

• Family Orthomyxoviridae
• Genera 3 Influenza virus Types
• Type A influenza viruses infect humans, birds
  other mammals.
• Type B influenza viruses primarily infects
  humans.
• Type C influenza viruses primarily infects
  humans.

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Influenza Virus Genera

• Type A
• moderate to severe illness-respiratory
  disease-fever, aches, cough, secondary pneumonia
• all age groups
• humans and other animals
• can be typed by hemagglutinin and neuraminidase
  protein (i.e. H3N2)
• Type B
• milder epidemics
• mainly affects humans
• primarily affects children
• Type C
• sporadic infections
• mainly affects humans
• primarily affects children and young adults

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Influenza structure
Influenza A Subtypes -Based on
Hemagglutinin (H) H1 to H16 Neuraminidase
(H) N1 to N9 144 different combinations
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Influenza Nomenclature
Location of Original Isolation
Year of Initial Isolation

• A/Fujian/411/2002 (H3N2)-like
• Strains A/Wisconsin/67/2005 (H3N2)-like
• (2006-7) A/New Caledonia/20/99 (H1N1)-like
• B/Malaysia/2506/2004

Subtype (Influenza A Viruses Only)
Original Lab ID
Type
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Influenza Nomenclature (adapted from CDC)

• Seasonal Influenza (common influenza)
• A respiratory illness that can be transmitted
  person to person. Most people have some immunity,
  a vaccine is available.
• Avian Influenza (bird flu)
• Influenza viruses that occur naturally among wild
  birds. There is no human immunity no vaccine.
• The H5N1 variant is deadly to domestic fowl can
  be transmitted from birds to humans.
• Pandemic Influenza
• A virulent human influenza that causes a global
  outbreak, or pandemic, of serious illness. There
  is little natural immunity, so the disease can
  spread easily from person to person.
• Currently, there is no pandemic influenza.

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Influenza Annual Impact
U.S. population 290 million
Seek Care
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Prerequisites for the Start of a Pandemic

• First, a new virus must emerge to which the
  general population will have no or little
  immunity
• Second, the new virus must be able to replicate
  in humans and cause disease, spread regionally
• Third, the new virus must be efficiently
  transmitted from one human to another.
• Spread of disease world-wide Pandemic

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Pandemic Flu Outbreaks occurred in

• 1918 Spanish Flu (H1N1)
• 1957 Asian Flu (H2N2)
• 1968 Hong Kong Flu (H3N2)

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1918 Spanish Flu Pandemic
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1918 Flu Epidemic Emergency Hospital, Camp
Funston, KansasPhoto Courtesy of National Museum
of Health and Medicine,Armed Forces Institute of
Pathology
Haskell county
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1918 Spanish Flu Pandemic

• 20 of World and 28 Americans infected
• Shortage of health professionals and supplies due
  to WWI
• 675,000 people died in U.S. out of 105 million
• 50-100 million died worldwide out of almost 2
  billion

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1918
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Bird Flu The Next Pandemic Concern WHY?

• Influenza is a disease of birds
• Rapidly mutates and changes
• Birds are mobile
• Birds that survive infection shed virus in feces
  for weeks

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Bird (avian) Influenza

• December 2003-June 2007
• 41 countries reported H5N1 bird flu in poultry
• Bird to humans-high mortality rate.
• Limited human to human transmission-only close
  contacts.
• Controlled by the depopulation of large flocks of
  poultry

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Bird (avian) Influenza cases
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Cause for concern?

• Wild ducks are now found that can shed virus
  without signs of infection.
• Experimental evidence that the virus is more
  lethal than when the epidemic first started in
  Asia.
• Has spread to mammalian species-large
  cats-previously thought to be immune.
• Large die-offs of migratory birds in
  China-unprecedented.

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Influenza Antigenic Change- A Hallmark

• Antigenic Drift
• Gradual continuous change in influenza virus
  hemagglutinin (HA) neuraminidase (NA) during
  replication
• Occurs with influenza A B
• Leads to new strains, allowing repeated
  infections
• Causes annual epidemics of seasonal influenza

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Influenza Antigenic Change- A Hallmark

• Antigenic Shift
• An abrupt change, infrequent unpredictable
• Process whereby existing surface HA and/or NA
  proteins are replaced by HA and NA proteins that
  are significantly different
• Occurs only with influenza A
• Results in a a new subtype (novel virus)
• Can result in pandemic influenza

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Transmission to Humans
Antigenic Shift
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H3N2
H5N1
Situation for concern ??!!!
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Avian Flu Human Infections 1918-2007
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Vaccines vs. Antivirals

• Vaccines Best prevention option, however
• limited supply of Avian influenza vaccine (bird
  strain)
• lag time to produce 6-9 months (human strain)
• manufacturing capacity stretched in pandemic
• efficacy dependent on correct match with strain
• Antivirals Best at STOPPING spread.
• effective for treatment and prophylaxis
• valuable adjunct to vaccines
• limited supply
• not all antivirals against avian flu strains

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How do Influenza vaccines work?

• World Health Organization (WHO) / Centers for
  Disease Control and Prevention (CDC)
• pick what influenza viruses subtypes
• done 9-10 months prior to current season
• 2 type A (H3N2, H1N),1 type B
• flu shot (inactivated virus) and nasal spray flu
  vaccine (live attenuated vaccine)

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Antivirals

• Four main antivirals
• Amantadine and rimantadine
• prevent virus replication (M2 ion channel
  inhibitors)
• affective only against Influenza A
• H5N1 is resistant
• Oseltamivir (Tamiflu) and Zanamivir (Ralenza)
• prevent virus from entering the cell
  (Neuraminidase inhibitors)
• affective against Influenza A and B
• 48 hours after symptoms or for prophylaxis

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Whos Watching Around the World?

• The World Health Organization (WHO)
• 6 Regional Offices (PAHO)
• 112 National influenza centers (NICs) in 82
  countries
• 4 WHO collaborating centers -WHOCCs
  (Australia, Japan, UK, and the USA)
• World-wide surveillance laboratories
• WHO makes recommendations on influenza vaccine

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Pandemic Influenza W.H.O. Phases
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Whos Watching the Nation?

• HHS Pandemic Influenza Response and Preparedness
  Plan,
• Centers for Disease Control
• HHS ordered 2 million doses of H5N1 vaccine from
  Aventis Pasteur Inc.
• US is working with WHO and SE Asian countries to
  enhance surveillance and Containment

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Whos Watching in Nebraska?

• Influenza Sentinel Provider Surveillance System
• 11 health care providers (report to CDC)
• Local Health Departments have flu surveillance
  plans
• Lab test result reporting
• About 65 labs reporting report total and () test
  results
• School absenteeism survey
• Local Health Departments enter data and do
  monitoring
• Hospital admissions survey (with influenza like
  illness)
• 19 district / local health departments
• 89 acute care hospitals

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What can you do?

• Get vaccinated
• If you have the flu, dont go to work
• Become educated about influenza.

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Cover your mouth and wash your hands!
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Resources

• CDC home page for influenza
• http//www.cdc.gov/flu
• http//www.cdc.gov/flu/weekly/fluactivity.htm
• U.S. web site for pandemic flu U.S. Pandemic
  Flu Plan and Preparedness Planning
• http//www.pandemicflu.gov/
• W.H.O. home page for influenza (including avian
• influenza)
• http//www.who.int/csr/disease/influenza/en/
• ProMED (Program for Monitoring Emerging Diseases,
  International Society for Infectious Diseases)
• http//www.promedmail.org

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Safety Resources

• Public Health Guidance for Community-Level
  Preparedness and Response to Severe Acute
  respiratory Syndrome (SARS),Version 2.3 July 20
  2004
• http//www.cdc.gov/ncidod/sars/guidance
• Biosafety in Microbiological and
• Biomedical Laboratories (BMBL),5th ed
• http//www.cdc.gov/od/ohs/biosfty/bmbl5/bmbl5toc.h
  tm

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Avian Flu Education

• A Short Quiz

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The current avian flu virus first appeared
in a. East Asia b. South Asia c. Middle
East

• A) East Asia. The first cases were in the
  Republic of Korea and Vietnam. Most of the
  outbreaks have been in East and Southeast Asia,
  though further outbreaks have been reported
  recently in Russia, Mongolia, Kazakhstan, Turkey,
  Croatia, Romania and Ukraine.

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Avian flu is most commonly spread by a.
Humans b. Pigs c. Birds

• C) Birds. Avian flu is passed from bird to
  bird, though it occasionally transmits to pigs.
  In very rare cases, the virus, which can be
  transmitted from wild to domestic birds, has been
  known to infect people who have come into direct
  contact with contaminated poultry or their waste.

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True or False There is now a bird flu vaccine
available for humans.

• False. Until the bird flu mutates into a virus
  that can be transmitted from person to person, no
  one can be sure if any vaccines being developed
  will work against the virus. Even if the vaccine
  works, they take a long time to manufacture so it
  is unlikely that enough vaccine would exist when
  a pandemic occurred.

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True or False People are safe from the pandemic
if they dont touch or go near any birds.

• False. A pandemic will occur if and when the
  bird flu strain mutates so infected humans can
  infect other humans. At that time, people who
  have never gone near birds will be at risk.
  Right now, birds infected with the bird flu virus
  can infect humans who come in contact with them.

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True or False No matter what type of influenza
you have, any of the antivirals available will be
able to treat your illness.

• False. Tamiflu and Ralenza at this time are
  known to be affective against Influenza A and B.
  Amantadine and Rimantadine are only affective
  against Influenza A, although H5N1 strains are
  resistant.

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True or False The U.S. government will be ready
to help victims of any pandemic.

• False. Individuals, families, and communities
  will be on their own. The government has advised
  individuals of the danger, saying thousands of
  communities could be countering influenza
  simultaneously with little or no assistance from
  adjacent communities, the state, or the federal
  government. Preparedness planning for pandemic
  influenza response must take the prospect into
  account.
• Source http//hhs.gov/pandemicflu/plan/part1.ht
  ml1

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True or False If you are young and healthy,
there is little for you to worry about as far as
contracting a pandemic illness.

• False. In the flu of 1918, the virus affected
  young people more so than older people. The flu
  of 1918 also originated from a bird flu virus.

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True or False During a pandemic, there may be
shortages of food, medicine, and other products.

• True. If the pandemic strikes, experts believe
  there will be shortages of food, medicine, and
  other products, because individuals who provide
  us with such items may be sick, disrupting the
  process. There also will be other social
  disruptions.

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Which strain of flu is responsible for more
deaths in the United States? a. Hong Kong flu
pandemic b. Avian flu c. Typical flu outbreak
20 years ago d. Seasonal flu outbreak expected
this year

• D) Seasonal flu outbreak expected this year.
  The CDC estimates that there might be 36,000
  fatalities from the flu this year, mostly in the
  elderly. This is more than the Hong Kong flu
  pandemic caused in the United States in 1968.

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When as the last major flu pandemic? a.
1900 b. 1918 c. 1950 d. 1968

• D) 1968. The Hong Kong flu, a virus that
  still circulates today, originated in Hong Kong
  and eventually spread to the United States,
  killing 34,000 Americans.