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AVIAN INFLUENZA DOES IT HAVE WINGS?. FRED Y. AOKI, MD INFECTION CONTROL CONSULTANT DEER LODGE CENTRE WINNIPEG. OBJECTIVES. DISCUSS THE EMERGENCE OF AVIAN INFLUENZA IDENTIFY RISK FACTORS FOR ITS ACQUISITION DISCUSS PREVENTION STRATEGIES. AVIAN INFLUENZA VIRUSES. ARE INFLUENZA A VIRUSES.
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AVIAN INFLUENZA DOES IT HAVE WINGS? FRED Y. AOKI, MD INFECTION CONTROL CONSULTANT DEER LODGE CENTRE WINNIPEG
OBJECTIVES • DISCUSS THE EMERGENCE OF AVIAN INFLUENZA • IDENTIFY RISK FACTORS FOR ITS ACQUISITION • DISCUSS PREVENTION STRATEGIES
AVIAN INFLUENZA VIRUSES ARE INFLUENZA A VIRUSES 15 DIFFERENT HEMAGGLUTININS 9 DIFFERENT NEURAMINIDASES H5 AND H7 VIRUSES MOST PROBLEMATIC
AVIAN INFLUENZA VIRUSES CAUSE 3 DIFFERENT TYPES OF DISEASE II. FOWL PLAGUE I. III. HIGHLY LETHAL BUT DEAD-END DISEASE
I. INFLUENZA A VIRUSES OF WILD DUCKS • PROBABLY FECAL-ORAL TRANSMISSION • CAUSE NO DISEASE • REPLICATE PRERENTIALLY IN GUT • EXCRETED IN FECES • SURVIVE IN LAKE WATER FOR 30 D AT 40 C • 30% OF MIGRATING YOUNG DUCKS EXCRETE • < 1% OF RETURNING DUCKS EXCRETE
II. FOWL PLAGUE = PANDEMIC INFLUENZA IN DOMESTIC POULTRY • RAPID SPREAD THROUGH FLOCKS • FULMINATING, DISSEMINATED VIRAL INFECTION • VIRUS IN ALL VISCERA • 80-100% MORTALITY
OBJECTIVE 1 DISCUSS THE EMERGENCE OF AVIAN INFLUENZA: • RESEVOIR IN ASYMPTOMATIC WILD DUCKS • FOWL PLAGUE IS DUE TO A HEMAGGLUTININ MUTATION THAT PERMITS INFECTION IN ALL TISSUES
II. FOWL PLAGUE OUTBREAKS 1959 – FIRST CONFIRMED OUTBREAK 24 OUTBREAKS, 14 SINCE 1994: 1992-95 MEXICO H5N2 1997 HONG KONG H5N1 2003 KOREA H5N1 JAPAN THAILAND VIETNAM CAMBODIA INDONESIA CHINA
II. H7N7 FOWL PLAGUE IN THE NETHERLANDS • 255 FARMS AFFECTED • 30 MILLION CHICKENS SLAUGHTERED (28% OF TOTAL CHICKEN POPULATION) • 171 MILLION DOLLAR DIRECT ECONOMIC LOSS • 4500 PERSONS EXPOSED • 553 (12%) ILL • 8% DEVELOPED CONJUNCTIVITIS • 2% DEVELOPED INFLUENZA-LIKE ILLNESS • 1 VETERINARIAN DIED KOUPMANS, 2004
III. HUMAN DISEASE DUE TO H5N1 AVIAN INFLUENZA VIRUS DIED 1997 HONG KONG 33% (6/18) 2003 HONG KONG 66% (2/3) 2003-05 VIETNAM THAILAND 56% (48/85)* *AS OF APRIL 14, 2005
III. 10 CASES H5N1 AVIAN INFLUENZA IN VIETNAM • MEAN AGE 13.7 YEARS • ALL PREVIOUSLY WELL • 9/10 HAD DIRECT CONTACT WITH SICK POULTRY; MEDIAN TIME BEFORE ILLNESS, 3 DAYS • ALL: FEVER, RESP SYMPTOMS, LYMPHOPENIA & THROMBOCYTOPENIA OF 75,500 • 7 HAD DIARRHEA NEJM, 2004
ALL MARKEDLY ABNORMAL CHEST XRAYS • RAPIDLY PROGRESSIVE PULMONARY INFILTRATES • 8 DIED, 1 RECOVERED WITHOUT SEQUELAE • (TO DATE ONLY 1 CASE OF MAN-TO-MAN TRANSMISSION [CHILD TO MOTHER, BOTH DIED])
OBJECTIVE 2 IDENTIFY RISK FACTORS FOR ITS ACQUISITION: CLOSE CONTACT WITH SICK BIRDS
OBJECTIVE 3 DISCUSS PREVENTION STRATEGIES: • BARRIER PRECAUTIONS • GOGGLES • MASKS • CHEMOPROPHYLAXIS • OSELTAMIVIR-EFFICACIOUS? • VACCINE
CIRCULATING WIDELY • GREAT POTENTIAL TO ACQUIRE CAPACITY FOR EFFICIENT HUMAN-TO-HUMAN SPREAD • CAUSES SEVERE ILLNESS (33-66% LETHAL) • GLOBAL POPULATION IS SUSCEPTIBLE CID, 2005
H5N1 VIRUS • H5N3 VACCINE POORLY IMMUNOGENIC IN MAN NICHOLSON, 2001 • AMANTADINE INHIBITED H5N1 1997 HONG KONG STRAIN • 8/8 CURRENT ISOLATES HAVE M2 MUTATION CHARACTERISTIC OF AMANTADINE RESISTANCE KLIMOV, 2004 • NAI DRUGS INHIBIT H5N1 IN VITRO, ARE EFFICACIOUS IN INFECTED MICE WEBSTER, 2001
DOES AVIAN INFLUENZA HAVE WINGS? NO…BUT IT HAS GRAVE IMPLICATIONS FOR HUMAN HEALTH