Avian Influenza A (H5N1)“Bird Flu”

TRCPANovember 18, 2005

Charles W. Mackett III, MD FAAFP

Executive Vice Chair

Department of Family Medicine

University of Pittsburgh Medical Center

Etiology

• Viral disease• Avian Influenza (HPAI)

– H5 and H7 – highly pathogenic– Human case fatality estimated to be as high has 50%, but

not definitely known

Cycle of Avian Influenza viruses in animals & humans

Tranmission also directly from birds to people.

Shore birds

Pandemic disease cycle

Natural avian influenza cycle

Mammals(primarily swine)

Waterfowl

Domestic birds

Humans

Direct bird to human transmission is also common

How is bird flu monitored?

• WHO and CDC maintain regional labs that test both bird and human specimens

• Periodic updates are provided

• The lab surveillance permits implementation of control measures if needed

• Vaccine trials are underway for the H5N1 strain, but are in early phases

WHO Pandemic Alert Phase Plan

Map of current outbreak

       FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS

Bird flu by the numbersHuman cases since date of onset (12/26/03) 125

Human deaths 64

Suspected human-to-human transmissions 2

Number of countries affected (since Dec 04) 12

Est. international airline passengers yearly 1.6B

Types of potential antivirals for bird flu 2

Known bird flu types 15

Bird flu that can be fatal to humans 1

Best case global deaths in pandemic 2-7M

Worst case potential global deaths 40-100M

*Source: World Health Organization

First case of bird flu in the U.S.

Previous avian flu in the U.S.

• Delaware (H7N2)– Reported February 6, 2003– 12,000 chickens– Low pathogenicity

• Texas (H5N2)– Reported February 23, 2004– 1st such case in U.S. in 20 years– 7,000 chickens– Highly pathogenic

• No H5N1

Human H5N1

• Incubation: 3-5 days• Few URI symptoms• Severe viral pneumonia picture

– Fever– Lymphopenia– Pulmonary infiltrates– Hypoxia

• Diarrhea (50%)• Time to death: 10 days (mean)

Transmission

• Respiratory droplets vs. aerosol

• Hand to hand

• Fomites

• Viral shedding starts 24 hours before clinical illness and lasts 5-7 days

Prerequisites for a pandemic

• Novel virus with no immunity

• Able to cause significant disease in humans

• Efficient human to human transmission– Re-assort during co-infection with H3N2– Evolve in a human by spontaneous mutation

Common pandemic features

• Herald wave (warning): up-tick in mortality at end of prior year

• Increased mortality

• Mortality shift to younger ages

• Multiple waves of increased mortality for several years

Potential for influenza pandemics

• All influenza viruses can mutate• Avian flu can cause illness in humans• Little to no herd immunity to avian strains among

humans• If avian viruses acquire human genes

– Facilitate efficient person-to-person transmission

• H5N1 of particular concern• No one can predict when a pandemic might occur

How is bird flu in humans treated?

• The H5N1 virus currently infecting birds in Asia that has caused human illness and death is resistant to amantadine and rimantadine

• Neurominidase inhibitors– oseltamavir (Tamiflu)– zanamavir (Relenza) inhaled, not stocked in house– Resistance can develop

• Additional studies are needed to prove the effectiveness of these medicines.

Defenses

• Vaccination• Prophylaxis• Rapid diagnosis• Treatment• Infection control

– Respiratory etiquette– Hand washing– Disinfection– Droplet precautions in hospitals

CDC recommendations

• Enhanced surveillance in the U.S. of H5N1. • Travelers to countries with known outbreaks of

influenza A (H5N1) should avoid:– Poultry farms – Contact with animals in live food markets – Surfaces that appear to be contaminated with feces

from poultry or other animals.

• CDC does not recommend any travel restrictions to affected countries at this time.

• For more information, visit Travelers' Health

CDC pandemic preparationProviding leadership and working with:

• National Pandemic Influenza Preparedness and Response Task Force, created in May 2005 by the Secretary of the U.S. Department of Health and Human Services

• Association of Public Health Laboratories on training workshops for state laboratories

• Council of State and Territorial Epidemiologists and others to help states with their pandemic planning efforts

• Department of Defense and the Veterans Administration on antiviral stockpile issues

• World Health Organization (WHO) and Vietnamese Ministry of Health to investigate influenza H5N1 in Vietnam and provide help in laboratory diagnostics and training

CDC pandemic preparation

• Offering laboratory testing for H5N1 viruses• Funding a $5.5 million initiative to improve influenza surveillance in

Asia• Holding or taking part in training sessions to improve local capacities to

conduct surveillance for possible H5N1 human cases• Developing and distributing reagents kits to detect the currently

circulating influenza A H5N1 viruses• Working together with WHO and the National Institutes of Health

(NIH) on safety testing of vaccine seed candidates and to develop additional vaccine virus seed candidates for influenza A (H5N1) and other subtypes of influenza A virus

UPMC Avian Flu Task ForceUnder the Direction of Loren Roth, MD, MPH Sr. V.P., Quality Care & Chief Medical Officer

• Comprised of experts in :– infectious disease -virology– critical care -epidemiology– emergency management -emergency medicine– pathology -mental health– medical laboratory -medical logistics– human resources -public affairs– corporate security -Center for Biosecurity of UPMC;

• The Task Force works closely in cooperation with the Allegheny County Health Department and Region 13 emergency management in facilitating and guiding UPMC’s preparations

• Preparation for a possible pandemic has been ongoing since early this year

Thank You!Many thanks to :

UPMC Avian Flu Task Force

Center for Biosecurity of UPMC

Questions?