impending doom !

Impending Impending Doom !Doom !

The World Coming To An End

Part III

Disease OccurrenceDisease Occurrence

•Endemic – normal levels within geographic regions.

•Epidemic – sudden severe outbreak within a region.

•Pandemic – epidemic becomes widespread (worldwide).

PandemicPandemic•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)

•Known pathogen

•Elderly affected most

•Vaccine available

•Localized occurrence

•Any time of year

•Unknown pathogen

•Atypical age groups

•No proven/available vaccine

•Worldwide occurrence

Most epidemics and pandemics caused by influenza.

InfluenzaInfluenzaThree Types

Type A

•Regular outbreaks

•Most widespread

•Responsible for pandemics

•Infects humans and animals

InfluenzaInfluenzaThree Types

Type B

•Sporadic outbreaks

•Mainly occurs in residential communities (e.g. nursing homes)

•Infects humans only

•Can cause epidemics, have not caused pandemics

InfluenzaInfluenzaThree Types

Type C

•Common

•Causes very mild symptoms or none at all

•Not a severe public health threat

Influenza A VirusInfluenza 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 VirusInfluenza 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 20Pandemics of 20thth Century 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 TysonThe 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)

• 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

• Fever

• Cough and runny nose

• Malaise with myalgia

• Headache, sore throat

• Extreme tiredness

What is the respiratory tract?What is the respiratory tract?

Respiratory Tract FunctionRespiratory 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 MicrobesRespiratory Tract Microbes

• Normal Flora

- Regular inhabitants- Rarely cause disease

Staphylococci sp. Cultured from Mr. Styer’s throat.

Gram negative cocci and gram positive rods from Ms. Shepard’s throat.

Respiratory Tract MicrobesRespiratory Tract Microbes• Nose

– Staphylococcus spp.– Staphylococcus aureus– Staphylococcus epidermidis

• Mouth and Oropharynx– Staphylococcus epidermidis– Streptococcus pneumoniae– Other Streptococcus spp.– Neisseria spp.– Haemophilus spp.– Anaerobic bacteria– Yeasts

Staphylococcus aureus

Respiratory Tract InfectionsRespiratory Tract Infections

• Respiratory tract constantly exposed to outside environment.

• Exposure to many airborne microbes.

Respiratory Tract DefenseRespiratory Tract Defense

• Physical barriers URT– Mucus

– Cilia

• Physical barriers LRT– Phygocytosis – killer white blood cells

Respiratory Tract PathogensRespiratory Tract Pathogens

• Upper Respiratory Tract– Viruses

• Corona viridae

• Adeno viridae

• Rhino viridae

– Group A Streptococcus– Corynebacterium diptheriae– Bordetella pertussis

Respiratory Tract PathogensRespiratory Tract Pathogens

• Lower Respiratory Tract– Viruses

• Influenza

• SARS

• Haantavirus

– Bacterial Pneumonia• 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

– “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

• 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!

CitationsCitationsCenters for Disease Control and Prevention (2005). Information About Influenza Pandemics [Internet]. Fact Sheet [cited July 28, 2005] http://www.cdc.gov/flu/avian/gen-info/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 UsedCholera Pandemic Picture http://www.authentichistory.com/images/postcivilwar/cartoons/1883_cholera_pandemic_cartoon.html

Portrait of Harry Tysonhttp://ring.uvic.ca/98oct16/EXEC.html

Chicken Imageshttp://dailyjournal.tripod.com/nov2002.htm

By

Tim Styer and Katie Shepard

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