Avian influenza (AI) is a Type A influenza virus, naturally found in some species of waterfowl and shorebirds. A particularly dangerous set of subtypes of this virus, called highly-pathogenic AI, is of particular concern due to its potential impact on wild birds, domestic poultry and human health if introduced into the United States.
History of AI Timeline
Although highly pathogenic avian influenza (HPAI) has not yet been found in the United States, NWDP uses an organized system of wild bird sampling, diagnostics and management in order to detect the possible entry of HPAI into the US as early as possible.
Some Methods of Potential Introduction of HPAI into the US:
• Legal or illegal wild (exotic) bird trade
• Wild migratory birds
Wild Bird Plan
The Wild Bird Plan, a collaborative effort between the US Department of Agriculture, US Department of the Interior and the US Department of Health and Human Services targets wild ducks, geese and shorebirds as key species of interest due to their migratory movement patterns and historical exposure to AI viruses.
Alaska is an area of concern for the potential introduction of HPAI into North American wild birds. In this region there is significant mixing of Asian and North American migratory birds, where the exchange of the virus could occur. Because of this mixing, the Pacific Flyway and Pacific Islands are a top priority in the monitoring of wild birds.
The United States is divided into four flyways that are each surveyed as the birds fly south from their summer breeding grounds. These flyways are: the Pacific, Central, Mississippi and Atlantic.
Five strategies are used for this surveillance:
1. Investigation of morbidity/mortality events in wild birds
Sampling of sick and dead birds offers the highest and earliest probability of detection of the HPAI virus if it is introduced into the US.
2. Monitoring live, apparently healthy wild birds
This effort targets the wild birds in North America that are most likely to be infected with HPAI because of their migratory movement patterns between Asia, Oceania and North America.
3. Monitoring hunter-killed birds
Using hunter check-stations, species that may to be exposed to HPAI due to their migratory patterns can be easily sampled to supplement live bird sampling.
4. Use of sentinel animals
There are two groups of animals that are used as sentinels for the early detection of HPAI. First, noncommercial poultry flocks are monitored by nearby commercial poultry farms for diseases that could spread between them. Second, disease-free duck flocks are placed in wetland environments where they can commingle with wild birds, then they will be tested for the presence of AI viruses.
5. Environmental sampling of water and bird feces
AI can be detected in the feces or swimming water of an infected bird and can also spread through these environmental media.
By using the five surveillance strategies outlined by the Wild Bird Plan, NWDP and its collaborators are proactively working to protect American people, wildlife and domestic animals from the spread of HPAI.
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