Home arrow Research arrow Health arrow Avian Influenza arrow Avian Influenza Strains with High and Low Pathogenicity
Avian Influenza Strains with High and Low Pathogenicity PDF Print E-mail
User Rating: / 0
PoorBest 
Written by Ramaz Mitaishvili   
Wednesday, 19 September 2007
The U.S. Department of Agriculture (USDA) classifies avian influenza viruses as low pathogenic avian influenza (LPAI) viruses or highly pathogenic avian influenza (HPAI) viruses, based on characteristics of a virus’ hemagglutinin cleavage site or its virulence in birds, as determined by laboratory testing. LPAI strains are endemic in wild birds worldwide and are responsible for most avian influenza outbreaks in poultry. LPAI strains with H5 and H7 subtypes sometimes evolve into highly pathogenic forms. HPAI strains are extremely contagious and cause severe illness and high mortality rates in poultry.
LPAI strains include:

    * H5N2, the cause of poultry outbreaks in New York, Maine, and California in 2002
    * H7N2, the cause of poultry outbreaks in Delaware, Maryland, and New Jersey in 2004

HPAI strains include:

    * H5N1, the cause of major poultry outbreaks in Southeast Asia
    * H7N7, the cause of a 2003 outbreak in the Netherlands
    * H7N3, the cause of a 2004 outbreak in British Columbia
    * H5N2, the cause of a 2004 outbreak in poultry in Texas

The 2004 outbreak in Texas was the first HPAI outbreak in the United States since a previous outbreak of H5N2 in 1983-84 in the northeastern United States. The 1983-84 disease control effort involved the destruction of approximately 17 million birds and cost more than $70 million.

Although avian influenza A viruses do not usually infect humans, several instances of human infections of avian influenza have been reported since 1997. Cases of avian influenza infection in humans are apparently caused by contact with infected poultry or with surfaces contaminated with avian influenza viruses.

LPAI strains associated with human infection include:

    * H9N2, which caused three cases of influenza-like illness in Hong Kong between 1999 and 2003, and other cases in China in 1998 and 1999
    * H7N2, which was detected by serology in one person involved in the culling of sick chickens during the response to a poultry outbreak in Virginia in 2002, and was isolated from a New York resident in 2003 (unknown source of the infection)

HPAI viruses associated with human infection include:

    * H5N1, which caused 51 deaths in Southeast Asia between January 2004 and April 2005
    * H7N7, which caused the death of a veterinarian as well as 83 cases of mild human disease (including conjunctivitis) during the 2003 poultry outbreak in the Netherlands.
    * H7N3, which caused 2 cases of very mild human disease (conjunctivitis, headache) in persons culling sick poultry in British Columbia in 2004
Health Monitoring
Surveillance and monitoring
Watch for symptoms for at least 10 days after last exposure to HPAI
Seek medical care for illness
Stay home until 24 hours after resolution of fever
Practice good respiratory and hand hygiene to lower transmission risk to contacts
Vaccination with current seasons influenza vaccine
Administration of antiviral drugs for prophylaxis
Daily for the duration of time responders have direct contact with infected poultry or contaminated surfaces
Commonly Asked Questions about Risk of Certain Exposures 
Risk from eating poultry?
No evidence that properly cooked poultry or eggs can be a source of infection for AI viruses
Heat foods to 70C, avoid cross-contamination, hand hygiene, no raw eggs in foods

Risk from feather products?
There is a risk to handling feather products
Feathers from affected countries are banned unless they have been processed to be rendered noninfectious

Risk from pet birds?
There is a risk to importing pet birds from affected countries
Importation from affected countries banned

Risk from bird feeders?
Risk of infection from bird feeders is low
Most wild birds traditionally associated with avian influenza viruses are waterfowl and shore birds
 
< Prev   Next >
[ Back ]
Advertisement

Foundation Georgia

www.foundationgeorgia.com