Download Avian Influenza – the next pandemic

Pandemic Influenza (“Bird Flu”)
Valerie Fletcher, M.D.
Infectious Diseases
Southern Ohio Medical Center
September 2006
Introduction
Influenza viruses are found in some animal species, and cause a
respiratory illness of varying severity.
Seasonal influenza affects 5 – 20% of population.
200,000 persons admitted with complications.
Influenza results in 36,000 deaths in US annually.
The Virus
Three strains of influenza virus – A, B, C
Influenza A causes illness in humans of all ages and some
animals, and is responsible for epidemics and pandemics.
Influenza B causes infection in humans and milder epidemics.
Influenza C causes a mild illness in children throughout the year.
Influenza Virus Nomenclature
Neuraminidase
Hemagglutinin
A/Wisconsin/67/2005 (H3N2)
Virus
type
Geographic
origin
Strain
number
Year of
Isolation
Virus subtype
Definitions
Seasonal influenza – respiratory viral illness that can be
transmitted from person to person and occurs in a cyclic
manner. Most people have some immunity.
Epidemic influenza – respiratory viral illness in greater
numbers than usual, but confined to a single population,
community or region.
Pandemic influenza – respiratory viral illness due to a new,
virulent strain, causing a worldwide outbreak. There is little or
no human immunity, and is easily spread from person to person.
Features of a Pandemic Influenza Virus
New influenza subtype to which there is little or no human
immunity.
Virus infects humans and causes illness.
Spreads easily, and there is sustained spread among humans.
6 Phases of Pandemic Alert – W.H.O.
Phase 1: interpandemic phase, low risk of human cases
Phase 2: new virus in animals, but no human cases, higher risk
of human cases
Phase 3: pandemic alert, no or very limited human-to-human
transmission.
Phase 4: clusters of human cases suggesting increased
adaptability of the virus, evidence of increased human-tohuman transmission.
Phase 5: larger clusters of human cases over longer period,
evidence of significant human-to-human transmission.
Phase 6: pandemic, efficient and sustained human-to-human
transmission
History
~ 35 pandemics recorded in the past 400 years.
3 pandemics in the past century.
1918 pandemic (H1N1) was most lethal in recorded history.
> 500,000 people deaths in US as a result of the 1918 Influenza
Pandemic (“Spanish flu”).
Three Pandemic Waves
Influenza and pneumonia mortality, UK - 1918 - 1919
1918 Influenza: The mother of all
pandemics. EID Jan 2006
1957 Asian Flu - H2N2
Originated in Far East in Feb 1957
Vaccine production began early May 1957: available in limited
supply in August 1957
“Double wave” of illness/death: 1st peak October 1957; 2nd peak
Jan/Feb 1958
Number of deaths in US 69,800 (Sept 1957 to March 1958)
1918
1957
1968
????
Worldwide Spread of H2N2 (“Asian Flu”) in 6 Months
Feb-Mar 1957
Apr-May 1957
Jun-Jul-Aug 1957
CDC
69,800 deaths (U.S.)
1968 Hong Kong Flu - H3N2
Four year wave: illness widespread in Dec 1968; same virus
returned following 3 flu seasons.
Elderly most vulnerable.
Number of deaths in US 33,800 (Sept 1968 – March 1969)
Impact mitigated: similar to 1957 Asian flu, peaked late in year.
1918
1957
1968
????
Timeline of Emergence of Influenza A Viruses in Humans
Avian
Influenza
Russian
Influenza
Asian
Influenza
Spanish
Influenza
H7
H5
H1
H3
Hong Kong
Influenza
H2
H1
1918
H9
H5
1957
1968
1977
1997
1998/9
2003
Avian influenza in Humans
Year
Strain
Country
Number of
confirmed human
cases
Number of
confirmed human
deaths
1997
A/H5N1
Hong Kong
18
6
1999
A/H9N2
Hong Kong
2
0
2003
A/H5N1
Hong Kong
2
1
2003
A/H7N7
Netherlands
89
1
2003
A/H9N2
Hong Kong
1
0
2003
A/H7N2
New York
1
0
2003
A/H7N3
Canada
-
0
2003-2006
A/H5N1
Viet Nam, Cambodia,
Indonesia, Azerbaijan,
China, Djibouti, Egypt,
Iraq, Turkey, and
Thailand
247
144
September 2006
Nations with confirmed cases of H5N1 Avian Influenza (July2006)
WHO
Cumulative Number of Confirmed Human Cases of Avian
Influenza A/(H5N1) Reported to WHO
2003
Country
2004
2005
2006
Total
cases
deaths
cases
deaths
cases
deaths
cases
deaths
cases
deaths
Azerbaijan
0
0
0
0
0
0
8
5
8
5
Cambodia
0
0
0
0
4
4
2
2
6
6
China
1
1
0
0
8
5
12
8
21
14
Djibouti
0
0
0
0
0
0
1
0
1
0
Egypt
0
0
0
0
0
0
14
6
14
6
Indonesia
0
0
0
0
19
12
46
37
65
49
Iraq
0
0
0
0
0
0
3
2
3
2
Thailand
0
0
17
12
5
2
2
2
24
16
Turkey
0
0
0
0
0
0
12
4
12
4
Viet Nam
3
3
29
20
61
19
0
0
93
42
Total
4
4
46
32
97
42
100
66
247
144
Total number of cases includes number of deaths.
WHO reports only laboratory-confirmed cases.
September 19, 2006
Transmission
Inhalation of droplets containing infectious material.
Direct contact.
Indirect contact.
Human to human transmission
Animal to human transmission.
Clinical Features
Fever
Chills
Cough
Sore throat
Body aches
Headache
Runny or stuffy nose
Nausea, vomiting, diarrhea
Complications
Pneumonia
Exacerbation of cardiac or lung diseases
Death
Persons at greatest risk of complications
Persons > 65 yrs
Infants
Persons with chronic disease
Pregnant women
Nursing home residents
Treatment
Antiviral agents
Supportive care – eg respiratory support, nutrition, hydration
Prevention
Influenza vaccine
Antiviral agents
Isolation
Quarantine
Definitions
Isolation – separation of an infected person from others during
period of disease communicability, in such a way that prevents,
as far as possible, the direct or indirect transfer of infectious
agent to susceptible persons.
Quarantine – separation and restriction of movement of
people who have been exposed to infectious agent, are
potentially infectious, but not yet showing signs of illness. May
be voluntary or mandatory.
Infection Control
Isolation – private room or cohort with other patients with same
illness.
N 95 masks for caretaker entering room.
Surgical masks for patients leaving isolation room if still
infectious.
Handwashing (or alcohol gel), gloves, gown, eye protection.
Surgical masks
Goggles
N95 mask
Handwashing
Hands are wet with running water.
Lather with soap for at least 15 seconds.
Rinse hand with running water.
Dry hands with disposable towel.
Turn off tap with disposable paper towel.
Place disposable towel in appropriate container.
Waterless alcohol-based hand rub or rinse
Approx. 3 ml of product taken from dispenser and rubbed
on dry skin for about 30 sec until alcohol evaporates.
Effective only on areas in contact with rub or rinse.
Does not remove soil or organic material.
Does not replace handwashing with soap and water if
hands are visibly soiled.
Contains 60 -70% alcohol.
Contains a moisturizer to prevent drying of skin.
DHHS Pandemic Preparedness – Five Priorities
Monitor disease spread to support rapid response.
Developing vaccines and vaccine production capacity.
Stockpiling antivirals and other countermeasures.
Coordinating federal, state and local preparation.
Enhancing outreach and communication planning.
Pandemic Planning Update II, DHHS
Secretary Michael Leavitt, 6/06
Pandemic Planning Update, DHHS
Secretary Michael Leavitt, 03/06
Vaccine Development
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
(WHO/CDC)
surveillance
select strains
prepare reassortants
standardize antigen
WHO/CDC/FDA
CDC/FDA
FDA
FDA
assign potency
review/license
FDA
manufacturers
formulate/test/package
clinic
vaccinate
CDC
Pandemic vaccine
Vaccine to target H5.
Production will start at the time the pandemic strain is detected.
Production may take up to 6 months.
Initial vaccine shortage expected.
2 doses may be needed.
Priority Groups for Pandemic Vaccine - DHHS
1A
1B
1C
1D
Healthcare workers involved in direct patient care; vaccine
and antiviral manufacturing personnel (9 million).
Highest risk group (26 million).
Household contacts of children < 6 months and severely
immunocompromised patients, pregnant women (11 mil).
Key government leaders and critical public health
pandemic responders (150,000).
2
High risk group, public safety and transportation workers.
3
Other key government health decision makers, mortuary
workers.
4
Healthy 2 – 64 year old persons not in the other groups
(180 million).
Antivirals
Oseltamivir (Tamiflu®) and Zanamivir (Relenza®).
Used for prophylaxis and treatment.
Supply limited – national stockpile.
Need for prioritization.
Unlikely to affect the course of the pandemic.
Other control measures
Educate to encourage self-diagnosis.
Public health information – risk avoidance, hygiene practices
Defer or limit travel
Seasonal influenza vaccine
Impact of Pandemic Influenza
Onset and scope of pandemic unpredictable.
Much depends on virulence of the virus and human immunity.
Availability of effective drugs and vaccines uncertain.
Health services will be overwhelmed.
Surveillance and early diagnosis important in curtailing spread.
Impact of Pandemic Influenza
Estimated attack rate 15% - 35%
Projected 314,000 – 733,000 hospitalizations
Projected 89,000 – 207,000 deaths
Meltzer et al, EID 1988
Comparison of 1918 Influenza Pandemic and projections for 2000
YEAR
1918
2000
World Population
1.8 Billion
5.9 Billion
Primary mode of
transportation
Troopships, railroad
Commercial aircraft,
automobiles
Time for virus to circle
the globe
4 months
4 days
Estimated deaths
worldwide
20+ million
60 million?
B. Wallace MD, P Smith MD. NYS
DOH 2005
Social disruption
Civil unrest
Schools closed
No transportation
Absenteeism
Disruption of essential and non-essential services
Economic impact
Preparing for a pandemic
Surveillance
Training/Education
Volunteer
Build a kit with essentials
Plan to care for self and others for ~ 72h without assistance
Preparing for a pandemic
Stockpile water and nonperishable food
First aid kit
Flashlight
Radio (battery-operated)
Medication
Tools
Clothing
Money
Preparing for a pandemic
Personal items
Pet supplies
Money
Gas
Identify resources/Contact information
Support system
During a Pandemic
Wash hands or use alcohol hand cleanser frequently.
Cover your cough.
Proper disposal of used tissue and other potentially
contaminated material.
Social distancing – stay home if sick and avoid people who are
sick.
Stay informed
pandemicflu.gov
cdc.gov 1-800-CDC-INFO (1-800-232-4636 or 1-888-232-6348)
who.org
Media
Local authorities
Pandemic influenza today
H5N1 is a likely candidate to cause a pandemic, however, it is
not expected to do so in its current form.
Rare cases of human to human transmission.
No cases of sustained transmission in humans.
No cases of H5N1 detected in birds or humans in North
America.