Avian Influenza

Background

Avian influenza (AI), or bird flu, is a group of viruses that affect both wild and domestic birds. The viruses are only found in a small number of birds in the wild, usually waterfowl and shorebirds, and rarely cause disease in these birds. The viruses are transmitted in fecal droppings, saliva, and nasal discharges.

Since 2003, a virulent form of AI has emerged in Southeast Asia, and now has been detected throughout Asia, parts of Europe, and parts of Africa. This highly pathogenic avian influenza (HPAI) H5N1 virus has resulted in the deaths of millions of domestic poultry, most euthanized to prevent spread.

As of September 2009 there have been over 400 human cases of highly pathogenic H5N1 reported (primarily in Asia), of which nearly 60% have been fatal. While the actual number of human cases and fatalities due to H5N1 is low when compared to the 36,000 deaths annually in the U.S. alone from human influenza viruses, there is great concern due to the high death rate in those people who are sick with H5N1. Additionally, there is worry that with human infection, the H5N1 virus could evolve by mutation or by obtaining genetic material from human influenza strains, and then human-to-human transmission could cause a worldwide influenza pandemic. Currently most human H5N1 infections are thought to be from close contact with infected poultry or contaminated materials, or by eating uncooked poultry products, not through wild bird to human transmission.

H5N1 has been detected and associated with deaths in wild birds in Africa, Asia, and Europe. These findings and the continuing geographic spread of H5N1 have led to concern that migratory birds could carry this HPAI strain into North America. There is equal concern that illegal importation of poultry or poultry products, movements of infected captive wildlife, or infected people could introduce H5N1 to the U.S. To date, highly pathogenic H5N1 has not been detected in wild birds, domestic poultry, or humans in North America.

An important conservation concern is that some public and animal health officials will blame wild birds for spreading H5N1 and suggest culling wild birds as a control mechanism. As stated by the Food and Agriculture Organization of the United Nations (FAO), “Indiscriminate culling of wild migratory bird populations would be ineffective in preventing further spread of avian influenza.” The most effective way to prevent transmission of AI between wild birds and domestic poultry (and subsequent risk to humans) is to improve bio-security around poultry farms, preventing contact with wild birds. Wisconsin has emergency response plans [PDF 548KB] in place if H5N1 or other highly pathogenic avian influenzas cause disease in the state’s wildlife, poultry, or public.

For information on Avian Influenza surveillance in WI, visit AI Surveillance.

Bird Flu (H5N1) and Swine Flu (H1N1): It's Confusing

The latest influenza virus in the news is 2009 H1N1 (often referred to as “swine flu”). H1N1 is receiving a lot of attention because it is causing significant illness in humans. While H1N1 ("swine flu") and H5N1 ("bird flu") are both subtypes of the Influenza A virus (and both contain an N1 component), the emerging H1N1 virus in humans is not directly related to the H5N1 avian influenza virus. H1N1 was first detected in the United States in April 2009 and is also causing human illness throughout many regions in the world. The virus was originally referred to as “swine flu” because laboratory testing showed that some of the genes in this new virus were related to the influenza viruses found in pigs. Further study has shown that this new virus if very different from what normally circulates in pigs, and H1N1 probably originated from a completely novel mixing of pig influenza viruses, avian influenza viruses and human influenza viruses. There are no known instances of people getting infected with H1N1 by exposure to pigs, birds, or other non-human animals. Rather H1N1 is spreading through human to human contact. In contrast, in regions of the world where H5N1 "bird flu" has been found, the virus has spread to humans through direct contact with sick birds.

Recently, 2009 H1N1 was confirmed in a single domestic pig in Minnesota. However, to date H1N1, has not been documented in domestic pigs in Wisconsin or in the state's scattered small populations of free-ranging pigs (also referred to as feral pigs). Though neither H1N1 "swine flu" or H5N1 "bird flu" have been found or are expected in Wisconsin wildlife, human health experts recommend that common sense precautions always be used when field dressing or butchering wild game such as feral pigs or wild birds. To avoid direct contact with blood and other body fluids, wear disposable gloves and eye protection, perhaps wear a simple mask to protect breathing passages, and follow proper food safely guidelines when cooking meat.

For more information on 2009 H1N1 "swine flu", see the following links:

• Center for Disease Control and prevention [Exit DNR]
• World Health Organization [Exit DNR]
• WI Dept. of Public Health and Safety [Exit DNR]

Additional Information

• Surveillance
• Safety Precautions for:
• General Public
• Hunters
• Bird Banders
• Wildlife Rehabilitators
• Frequently Asked Questions
• Avian Influenza Brochure [PDF 170KB]

Avian Influenza Updates

• National Wildlife Health Center [Exit DNR]
• United States Department of Agriculture [Exit DNR]
• U.S. Fish and Wildlife Service [Exit DNR]

Information on Avian Influenza and People

• Centers for Disease Control [Exit DNR]
• World Health Organization [Exit DNR]
• Department of Health and Human Services [Exit DNR]
• Wisconsin Department of Health and Family Services [Exit DNR]

Information on Avian Influenza and Wild and Domestic Birds

• Food and Agriculture Organization of the United Nations [Exit DNR]

Questions regarding Avian Influenza, please contact Wildlife Health

Questions for Wildlife Management