August 23, 2004

US Declared Free Of Avian Influenza Virus

The U.S. Department of Agriculture' Animal and Plant Health Inspection Service this week has notified the World Organization for Animal Health, known as OIE, that the U.S. is now free of highly pathogenic avian influenza according to the definition of OIE's Terrestrial Animal Health Code, a USDA-APHIS press release stated.
 
Countries that wish to have a disease status changed by OIE are required to notify that organization when the appropriate definition has been met.
 
"It is always a pleasure to be able to call the OIE and report that we've eradicated a disease in this country," said John Clifford, USDA's chief veterinarian. The highly pathogenic avian influenza eradication project was such a success because of the cooperation between APHIS, state and local governments as well as the poultry industry, Clifford said.
 
APHIS sent a letter of confirmation to OIE on Aug. 19 stating that the required six months have passed since the detection, eradication, cleaning and disinfection of two live bird markets and one backyard flock in Gonzalez County, Texas, were completed, the release said. Targeted and extensive surveillance has not detected any further evidence of the virus. The U.S.' HPAI-free status has been confirmed by the OIE in its weekly animal health news report (www.oie.int), the release said.
 
Avian influenza viruses can be classified into low pathogenic and highly pathogenic forms based on the severity of the illness they cause. Most avian influenza virus strains are low pathogenic and typically cause few or no clinical signs in infected birds. Avian influenza viruses can infect chickens, turkeys, pheasants, quail, ducks, geese and guinea fowl, as well as a wide variety of other birds.
 
Low pathogenic avian influenza viruses are endemic in wild waterfowl and migrating bird populations worldwide. Therefore, it is not a disease APHIS can expect to totally eradicate. Consequently, each year there are some occurrences of low pathogenic avian influenza in domestic poultry, particularly where birds are raised outdoors. However, some low pathogenic strains are capable of mutating under field conditions into high pathogenic viruses.
 
High pathogenic avian influenza is an extremely infectious and fatal form of the disease for chickens. It can strike poultry quickly without any infection warning signs, the APHIS release said. Once established, the disease can spread rapidly from flock to flock.
 
APHIS works to keep high pathogenic avian influenza from becoming established in the U.S. poultry population. It is essential for the U.S. poultry industry to be alert to this disease threat, the release said.