Transcript Pandemics/Flu

Impending Doom !
The World Coming To An End
Part III
Disease Occurrence
•Endemic – normal levels within geographic regions.
•Epidemic – sudden severe outbreak within a region.
•Pandemic – epidemic becomes widespread (worldwide).
Pandemic
•Global outbreak.
•Caused by new subtypes – novel pathogen.
•High person-to-person susceptibility.
•Unusually high mortality.
Cholera Pandemic Cartoon, 1883
Epidemic
versus
Pandemic
•Seasonal (mainly winter)
•Any time of year
•Known pathogen
•Unknown pathogen
•Elderly affected most
•Atypical age groups
•Vaccine available
•No proven/available
vaccine
•Localized occurrence
•Worldwide occurrence
Most epidemics and pandemics caused by influenza.
Influenza
Three Types
Type A
•Regular outbreaks
•Most widespread
•Responsible for pandemics
•Infects humans and animals
Influenza
Three Types
Type B
•Sporadic outbreaks
•Mainly occurs in residential communities (e.g.
nursing homes)
•Infects humans only
•Can cause epidemics, have not caused pandemics
Influenza
Three Types
Type C
•Common
•Causes very mild symptoms or none at all
•Not a severe public health threat
Influenza A Virus
•ssRNA virus
•Contains two membrane proteins
•Hemagglutinin (“H”)
- Initiates infection by binding to receptors on host
cell’s membrane.
•Neuraminidase (“N”)
- Enzymatic properties of N destroy host cell
receptors and allows viral infection of cell.
Influenza A Virus
•Subtypes vary by types of H and N membrane proteins
- 15 different H proteins identified (H1, H2, etc.)
- 9 different N proteins identified (N1, N2, etc.)
•Virus identified and named by H and N membrane proteins
•Many different combinations of H and N proteins possible
•Only some Influenza A subtypes currently cause human infection
- H1N1, H2N2, and H3N2
•Others are common in animal species
•All common in avian species
Pandemics of 20th Century
Spanish Flu – 1918 – A (H1N1)
•50 million dead worldwide
•500,000 dead in U.S.
Asian Flu – 1957 – A (H2N2)
•70,000 dead in U.S.
Hong Kong Flu – 1968 – A (H3N2)
•34,000 dead in U.S.
The Case of Harry Tyson
54 year old male brought to Norfolk General Hospital
Patient presented with:
•Fever (103.2 degrees F)
•Productive cough with blood
•Sore throat
•Myalgia (General muscle pain)
•Dyspnea (Difficulty breathing) on day 5
Subsequent Complications:
•Respiratory failure on day 5 and ARDS
•Renal and Cardiac failure days 6 & 7
•Died on day 8
•Wife and son admitted on day 5
with similar symptoms
Initial Treatment & Diagnosis
• Patient given Oseltamivir on days 5-8 with no
improvement
• Wife and son also administered drug
• Son died on day 14 and mother recovered
• Initial diagnosis: Influenza with complicating
secondary bacterial pneumonia
Final Diagnosis
• Father owned chicken farm where
family worked
• Father involved in breeding hybrid chicken
– Large Asian variety with fast producing
American variety
• Father imported eggs from S.E. Asia illegally
• Exposed to products of the eggs
Suspected Pathogen:
Influenza Virus A (H5N1)
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Father, Mother, and son all test positive
Chickens test positive
The USDA and CDC contacted
Farm Quarantined
Chickens Destroyed
So, you have the flu…
Virus causes upper and or lower respiratory tract
infection as the virus uses cells for lytic reproduction
Symptoms of the Flu
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Fever
Cough and runny nose
Malaise with myalgia
Headache, sore throat
Extreme tiredness
What is the respiratory tract?
Respiratory Tract Function
• Gas exchange
- Take in oxygen and expel carbon dioxide
• Sound
- Movement of gas through mouth and over larynx
and pharynx allows sound production
Respiratory Tract Microbes
• Normal Flora
- Regular inhabitants
- Rarely cause disease
Gram negative cocci and gram positive
rods from Ms. Shepard’s throat.
Staphylococci sp. Cultured from Mr. Styer’s throat.
Respiratory Tract Microbes
• Nose
– Staphylococcus spp.
– Staphylococcus aureus
– Staphylococcus epidermidis
• Mouth and Oropharynx
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Staphylococcus epidermidis
Streptococcus pneumoniae
Other Streptococcus spp.
Neisseria spp.
Haemophilus spp.
Anaerobic bacteria
Yeasts
Staphylococcus aureus
Respiratory Tract Infections
• Respiratory tract constantly exposed to outside
environment.
• Exposure to many airborne microbes.
Respiratory Tract Defense
• Physical barriers URT
– Mucus
– Cilia
• Physical barriers LRT
– Phygocytosis – killer white blood cells
Respiratory Tract Pathogens
• Upper Respiratory Tract
– Viruses
• Corona viridae
• Adeno viridae
• Rhino viridae
– Group A Streptococcus
– Corynebacterium diptheriae
– Bordetella pertussis
Respiratory Tract Pathogens
• Lower Respiratory Tract
– Viruses
• Influenza
• SARS
• Haantavirus
– Bacterial Pneumonia
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Streptococcus pneumoniae
Mycoplasma pneumoniae
Pseudomonas aeruginosa
Legionella pneumophila
The Monster That Looms: H5N1
• Currently unable to transmit human-to-human (as
seen with H1, H2 & H3 strains)
• Infection only with direct contact with infected
animal
• Can infect across breeds: birds and mammals
• Causes atypical immune response
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“Cytokine Storm” that body cannot handle
Fluid (blood) fills the lungs as body fails
Secondary infections are rampant
Seen in the “Spanish Flu” of 1918
Review and Reflection
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Differentiate Epidemic and Pandemic outbreaks:
Give the parts and function of each part of the respiratory tract:
Give our typical respiratory tract defense against infection:
List two non-pathogenic and two pathogenic respiratory tract
microbes:
• Describe how an H2N2 strain of virus differs from an H5N2
strain. For which one is there a vaccine available?
• Describe what is meant by a secondary bacterial infection and
how would a hospital test for this?
Writing Prompt
• Write a one page, double-spaced essay on what you
think would happen if there was, in fact, an influenza
AH5N1 outbreak. How would we react to the threat
both locally and globally ? What would we have to
do to contain the disease, yet survive as a society?
Examine the effect on things like the economy, travel,
as well as on everyday life such as school and grocery
shopping. Be thoughtful and creative!
Citations
Centers for Disease Control and Prevention (2005). Information About Influenza
Pandemics [Internet]. Fact Sheet [cited July 28, 2005] http://www.cdc.gov/flu/avian/geninfo/pandemics.htm
Centers for Disease Control and Prevention (2005). Key Facts About Influenza and
Influenza Vaccine [Internet]. Fact Sheet [cited July 28, 2005]
http://www.cdc.gov/flu/keyfacts.htm
Centers for Disease Control and Prevention (2004). Update on Avian Influenza A (H5N1)
[Internet]. Health Alert Network. [cited July 28, 2005]
www.phppo.cdc.gov/han/archivesys/viewmsgv.asp?alertnum=00209
Images Used
Cholera Pandemic Picture
http://www.authentichistory.com/images/postcivilwar/cartoons/1883_cholera_pandemic_c
artoon.html
Portrait of Harry Tyson
http://ring.uvic.ca/98oct16/EXEC.html
Chicken Images
http://dailyjournal.tripod.com/nov2002.htm
By
Tim Styer and Katie Shepard
This is an unfinished product!