USDA Confirms Highly Pathogenic H5N2 Avian Influenza in Dixon County, Nebraska

CDC considers the risk to people from these HPAI H5 infections in wild birds, backyard flocks and commercial poultry, to be low

WASHINGTON, May 12, 2015 -- The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of highly pathogenic H5N2 avian influenza (HPAI) in a commercial layer flock in Dixon County, Nebraska. The flock of 1.7 million chickens is located within the Central flyway where this strain of avian influenza has previously been identified. CDC considers the risk to people from these HPAI H5 infections in wild birds, backyard flocks and commercial poultry, to be low. No human infections with the virus have been detected at this time.

Samples from the chicken flock, which experienced increased mortality, were tested at the South Dakota State University Animal Disease Research & Diagnostic Laboratory and the APHIS National Veterinary Services Laboratories (NVSL) in Ames, Iowa confirmed the findings. NVSL is the only internationally recognized AI reference laboratory in the United States.   APHIS is working closely with the Nebraska Department of Agriculture on a joint incident response. State officials quarantined the premises and birds on the property will be depopulated to prevent the spread of the disease. Birds from the flock will not enter the food system. As a reminder, the proper handling and cooking of poultry and eggs to an internal temperature of 165 ˚F kills bacteria and viruses.

The United States has the strongest AI surveillance program in the world. As part of the existing USDA avian influenza response plans, Federal and State partners as well as industry are responding quickly and decisively to these outbreaks by following these five basic steps: 1) Quarantine – restricting movement of poultry and poultry-moving equipment into and out of the control area; 2) Eradicate – humanely euthanizing the affected flock(s); 3) Monitor region – testing wild and domestic birds in a broad area around the quarantine area; 4) Disinfect – kills the virus in the affected flock locations; and 5) Test – confirming that the poultry farm is AI virus-free. USDA also is working with its partners to actively look and test for the disease in commercial poultry operations, live bird markets and in migratory wild bird populations.

USDA will include this information in routine updates to the World Organization for Animal Health (OIE), and will notify international trading partners of this finding as appropriate. OIE trade guidelines call on countries to base trade restrictions on sound science and, whenever possible, limit restrictions to those animals and animal products within a defined region that pose a risk of spreading disease of concern.

These virus strains can travel in wild birds without them appearing sick. People should avoid contact with sick/dead poultry or wildlife. If contact occurs, wash your hands with soap and water and change clothing before having any contact with healthy domestic poultry and birds.

All bird owners, whether commercial producers or backyard enthusiasts, should continue to practice good biosecurity, prevent contact between their birds and wild birds, and report sick birds or unusual bird deaths to State/Federal officials, either through their state veterinarian or through USDA’s toll-free number at 1-866-536-7593. Additional information on biosecurity for backyard flocks can be found at http://healthybirds.aphis.usda.gov.

Additional background
Avian influenza (AI) is caused by an influenza type A virus which can infect poultry (such as chickens, turkeys, pheasants, quail, domestic ducks, geese and guinea fowl) and is carried by free flying waterfowl such as ducks, geese and shorebirds. AI viruses are classified by a combination of two groups of proteins: hemagglutinin or “H” proteins, of which there are 16 (H1–H16), and neuraminidase or “N” proteins, of which there are 9 (N1–N9). Many different combinations of “H” and “N” proteins are possible. Each combination is considered a different subtype, and can be further broken down into different strains. AI viruses are further classified by their pathogenicity (low or high)— the ability of a particular virus strain to produce disease in domestic chickens.

The HPAI H5N8 virus originated in Asia and spread rapidly along wild bird migratory pathways during 2014, including states in the Pacific flyway. However, HPAI H5N8 recently was confirmed in a state along the Mississippi flyway. The HPAI H5N8 virus has mixed with North American avian influenza viruses, creating new mixed-origin viruses. These mixed-origin viruses contain the Asian-origin H5 part of the virus, which is highly pathogenic to poultry. The N parts of these viruses came from North American low pathogenic avian influenza viruses.

USDA has identified two mixed-origin viruses: the HPAI H5N2 virus and new HPAI H5N1 virus. The new HPAI H5N1 virus, which has been identified only in the Pacific flyway, is not the same virus as the HPAI H5N1 virus found in Asia, Europe and Africa that has caused some human illness. The HPAI H5N2 virus has been detected in the Pacific, Mississippi and Central flyways. The HPAI H5N8 virus has been detected in the Pacific and Mississippi flyways.

Detailed analysis of the virus is underway in cooperation with the U.S. Centers for Disease Control and Prevention. For more information about the ongoing avian influenza disease incident visit the APHIS website. More information about avian influenza can be found on the USDA avian influenza page. More information about avian influenza and public health is available on the CDC website.