Transcript Powerpoint

Pandemic
Why a Global Influenza Pandemic is
Not a Cause for Concern
Ted Espenschied
Background
Influenza
• Influenza is an infectious
disease common to birds
and mammals, caused by a
family of RNA viruses
• Common symptoms of
influenza include fever, sore
throat, muscle ache,
headaches, and respiratory
impairment
• Influenza itself is not a
lethal pathogen – however,
when a flu patient contracts
pneumonia, death can
occur
Transmission
• Influenza is a contagious disease that
is spread by respiratory aerosols
• An infected person discharges
viruses particles with each cough or
sneeze
• Many healthy adults can be
contagious for up to 1 full day before
they experience symptoms
• An infected individual can be
contagious for up to 5 days after the
onset of symptoms
Seasonality
Centers for Disease Control: Influenza: The Disease (http://www.cdc.gov/flu/about/disease.htm)
Who is Vulnerable
• Anyone can get the flu, during any flu season
• People 65 and older, as well as individuals with chronic
medical conditions are especially vulnerable
• Very young children (whose lungs and immune system
are not fully developed) are also vulnerable
• The CDC estimates that between 5% and 20% of the
U.S. population contracts the flu every year
• An average of 36,000 people die from influenza in the
U.S. every year
• More than 200,000 must be hospitalized
Context
History: Past Pandemics
• It is difficult to determine if past pandemics were cause
by the influenza virus
• Many other diseases (diphtheria, typhoid fever, and
pneumonic plague) share similar symptoms
• Most infamous epidemic: 1918-1919 Spanish Flu
• Current estimates are that 50 to 100 million people
died worldwide
• Extremely high infection rate - 50%
• Killed between 2% and 20% of those infected (typical
flu mortality rate = 0.1%)
• Unusual for influenza, this pandemic killed mostly
young adults
Avian (Bird) Flu
• Avian Influenza is an infectious disease of
birds, especially domestic birds (poultry)
• There are two forms: mild (common) and
extremely lethal (rare)
• Highly pathogenic forms (H5 and H7 subtypes)
• Spread: wild waterfowl infect domestic flocks
with highly pathogenic H5N1 strains
• Associated with heightened risk of human
exposure and infections
Avian Flu, (Cont’d)
• However…
• Influenza viruses are normally very species-specific
(spillover is rare)
• H5N1 has the most potential to harm humans
– Has jumped species 3 times in recent history (1997, 2003,
and 2004)
– Has the potential to “go global”
• 2 Mechanisms for improving transmissibility to people
(jumping the species gap)
– Reassortment – exchange of genes with human flu virus
during co-infection
– Gradual process of adaptive mutation
So Why Shouldn’t We Worry?
Vaccinations & Treatment
• According to the CDC, “the single best way to protect against the flu is to
get vaccinated each year.”
– Flu Shot (good for about 6 months)
– LAIV (Live Attenuated Influenza Vaccine) Nasal Spray
– Each vaccine contains 3 types of virus: 2 A viruses (H3N2 & H1N1) and
1 B virus
– People at high risk or people exposed to high-risk individuals
– The effectiveness of the vaccine depends on the age and health of the
individual, as well as on the similarity to the virus strains in circulation
• Anti-viral medication
• Antibiotics (fight secondary infection, e.g. pneumonia)
• The Respiratory Viruses section of The National Institute of Allergy and
Infectious Disease (part of the NIH) is developing vaccines for all 16 of the
hemaglutinin proteins (the ‘H’ in HxNy) found in waterfowl virus type A
Monitoring
• The CDC collects flu data year round
• During the flu season, the CDC reports on
influenza ‘activity’ each week from October
through March every year
• Viral surveillance (in labs across the U.S.)
• Sentinel physician surveillance
• Mortality surveillance
• State epidemiological reports
• Influenza-associated pediatric mortality and
hospitalizations
• According to the website www.pandemicflu.gov,
the U.S. is at Stage 0, with no cases of domestic
animal outbreaks of avian flu
• The world is at Phase 3 “No or very limited
human-to-human transmission”
Julie Louise Gerberding,
M.D., MPH – Director of
the CDC
Global Monitoring
• The WHO is keeping track of incidents and is
characterizing the H5N1 Avian Influenza strain
• Pandemic Preparedness Plan
– Reduce Human Exposure to H5N1
– Strong Early Warning Systems
– Intense Rapid Containment Operations
– Global Capacity to Cope with Pandemic
– Coordination of Global Influenza Research
Adequate Response
• The WHO has an effective response protocol for
instances of highly infectious avian flu
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Rapid culling
Proper carcass disposal
Quarantining and disinfection of farms
Strict “Biosecurity” (sanitary) measures
Restrictions on the movement of poultry (especially
between countries)
– Vaccination (as a supplementary emergency measure)
Larger Problems
• Other lethal, infectious diseases (Ebola?)
• HIV/AIDS
• Respiratory sincytial virus (RSV):
– Most common cause of severe respiratory illness in
children
– Leading cause of death by respiratory illness in
individuals >65
• In the grand scheme of things, there are far more
pressing issues in the realm of global health, with
respect to infectious disease as well as other
health hazards
Influenza at UNC
• Flu vaccine – according to the Campus
Health website, the vaccine is 75-90%
effective
• The Influenza vaccine is 1 of 8
recommended vaccinations for college
students (among Hepatitis A and B, HPV,
Meningococcal, Mumps, Whooping
Cough, and Chicken Pox)
Mary Covington, MD –
• Campus Health provides up-to-date
Assistant Vice Chancellor for
information to students about
Campus Health Services
recognizing, preventing, and managing
the flu on campus every year
Media Hype?
• Where is this bird flu? I’ve been waiting for four years now…
• It’s limited occurrence has been confined to Asia and Africa,
and has never been found in the U.S.
• So is bird flu the “disease of the moment?”
Evolution: 2 Perspectives
• Influenza Virus
– If a strain of the influenza virus becomes too
lethal, it will eventually kill off its host species, and
it too will die
– In the framework of evolution and propagation of
the species, this is unfavorable
• People
– A strong new driver for natural selection
– An evolutionary push to become a more fit
species
Benefits?
• Environmental – reduce the human burden on
natural systems
• Ecological – is the earth at carrying capacity
for Homo sapiens, given our current
technological advancements?
• Economic – greater availability of resources
and raw materials?
Sources
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Centers for Disease Control and Prevention
National Institute of Health
World Health Organization
http://www.ifpma.org/influenza/content/images/diagram_vir
us_thumb.jp
• http://www3.niaid.nih.gov/healthscience/healthtopics/Flu/de
fault.htm
• http://www.pandemicflu.gov/index.html
• UNC Campus Health Services