Avian influenza (Avian flu), by Bob Sallinger
Avian Influenza has received a tremendous amount of attention during the past year. While the virus is a legitimate cause for concern and pro-active preparatory response planning, the identification of the virus has also triggered an unfortunate proliferation of political grandstanding and irresponsible media driven fear mongering. While Portland Audubon applauds the response planning that has been occurring at both the State and Federal levels, we also believe that it is critical that we move beyond the culture of fear that has vastly exaggerated the danger from Ebola Virus, Hantavirus and West Nile Virus during the past decade. Preparation and awareness are surely appropriate, but Americans would also be well served by a greater commitment to context and proportion both in the coverage of emerging disease issues and in the allocation of resources. According to the Center for Disease Control the single most important thing Americans can do to prevent contracting disease is not to worry about their neighbors chickens, the mosquito buzzing about their ears or the house mouse scampering about their attic, but rather simply to wash their hands.
Avian Influenzas are viruses that occur naturally in birds worldwide. Typically wild birds carry these viruses in their intestines and do not get sick from them. These viruses however, can be extremely lethal to domestic poultry. Avian Influenzas are divided into two categories, “high pathogenic” and “low pathogenic” depending upon how lethal they are to domestic fowl. Since 1988 there have been at least eight major outbreaks of highly pathogenic Avian Influenza worldwide. The current outbreak caused by a strain known as H5N1 was first identified in Asia in 2003. Since that time, the H5N1 strain has been identified in Europe and Asia but has not yet made its way to North America.
Three things differentiate the H5N1 strain from other recent outbreaks of Avian Flu. First, it has proven to be exceptionally lethal to domestic fowl. Second, unlike most Avian Influenzas, H5N1 has also proven to be lethal to many species of wild birds. Finally, H5N1 can be transmitted to humans. As of March 2006, there have been 180 cases worldwide of humans contracting H5N1 with about half of those cases proving lethal. Almost all cases have been directly linked to intense exposure to infected flocks of domestic poultry. The concern is that the H5N1 strain will mutate in a manner that will allow it to be easily transmitted from human to human leading to a possible pandemic.
Efforts to develop plans to address the H5N1 strain of Avian Influenza when it arrives on the United States are laudable. Plans have recently been released to provide for surveillance to identify the virus as soon as it enters the United States, to rapidly respond and isolate any outbreaks in domestic poultry flocks and to prepare for worst case scenarios should H5N1 become easily transmitted from human to human and achieve pandemic proportions. At the same time however it is critical to remember that H5N1 is not currently in North America. H5N1 has not mutated in a manner that allows it to be easily transmitted from human to human. Finally, H5N1 has infected less than 200 people worldwide during the past three years.
The following Q&A addresses several of the most common questions that we are receiving at Audubon Society of Portland. We would refer readers to any of the websites listed at the end of this article for more in-depth discussions of H5N1.
Can you catch H5N1 from wild birds: H5N1 has not yet entered North America. There is currently no possibility of catching H5N1 from wild birds. Even in countries where H5N1 has been identified in wild bird populations, there are zero identified cases of humans catching H5N1 from wild birds. Transmission to humans has been closely associated with situations where there is extremely close contact with diseased domestic birds. While it is theoretically possible to catch H5N1 from wild birds, there are simply no cases to date anywhere in the world. Typical human interactions with wild birds do not resemble the kinds of intensive contact with large numbers of infected domestic birds that have resulted in human contraction of the virus.
What impact will H5N1 have on native North American birds: It is unknown what, if any, impact H5N1 will have on native North American birds. Traditionally wild birds have served as carriers of Avian Influenza but have rarely become ill from the virus. H5N1 is of particular concern because it has resulted in uncommonly high mortality rates in wild birds affected by the virus. In China nearly 10% of the world’s known population of bar-headed geese have died from the virus. To date, more than 40 species of wild birds in Asia, Africa and Europe are known to have died from the virus including ducks, geese, storks, egrets, herons, gulls and falcons. The virus has also infected a variety of mammal species. There are a variety of poorly understood factors will influence the viruses impacts on North American wildlife populations. These include variations among species’ susceptibility to any given disease as well as variations in ecology, geography, migratory routes, and inter-species interactions. The virus itself has been mutating as it has moved eastward adding additional unpredictability. Wild birds have evolved with various forms of avian flu. Typically with an new emerging disease the species of greatest concern are those that are already threatened or endangered and least able to withstand initial impacts until the population builds general immunity over time.
Would reducing wild bird populations help slow the spread of H5N1: All major health and wildlife organizations agree that killing wild birds would be ineffective in slowing or stopping the spread of H5N1. Leading experts including the World Health Organization, Food and Agricultural Organization of the United Nations, and World Organization for Animal Health all emphasize that culling wild bird populations is highly unlikely to stop the spread of the disease, and would only divert resources away from more important disease control measures. On March 23, 2006 a joint statement by the United States Secretary’s of Health, Agriculture and the Interior reaffirmed that killing wild birds to prevent the spread of H5N1 would be ineffective and inappropriate.
Are migratory birds the most likely pathway by which H5N1 is likely to arrive in the United States: Despite heavy media focus on migratory birds as one potential pathway for H5N1 to arrive in the United States, research shows that the spread of the virus in Asia and Europe has been most closely associated with the movement of poultry and poultry products. While it is possible that migratory birds summering near the Bering Strait could intermingle with diseased birds from Asia and bring the disease southward during the fall migration, the United States needs to be equally concerned about importation of poultry and poultry products as well as the legal and illegal importation of wildlife and wildlife products from abroad. According to the United States Geological Survey, it is unclear whether wild birds that are infected with the virus would even be capable of migration, thus reducing their viability as a potential vector.
Should you continue to feed wild birds: There is no reason to discontinue feeding wild birds. However feeders can serve as a mechanism to spread a variety of diseases among individual birds. They can also increase mortality rates caused by natural predators such as hawks and introduced predators such as housecats that learn to frequent feeders. In order to reduce the risk of disease transmission and predation at feeders we recommend that you do the following:
- Feed only limited amounts of food on a daily basis
- Feed only fresh, natural foods
- Clean feeders weekly with a 10% bleach solution
- Periodically “take a break.” Stop feeding for 5-7 days to allow birds to disperse and reduce habitual predation by natural and introduced predators
- If you signs of disease at you feeder, stop feeding for a 3-4 weeks
- Naturescape your yard to provide for the birds in a more natural manner
- Remember that bird feeding simply supplements a natural diet. The birds will not starve if you discontinue feeding.
What should you do if you find an injured bird: Members of the general public should always use caution when handling sick or injured wild animals. This is not because of risk presented by avian flu but rather because wild animals can carry a variety of different diseases that can be spread to humans via inappropriate handling. We recommend that you avoid direct contact with any sick or injured animal. Use either gloves or some other device to move sick or injured animals into an escape proof box and transport directly to the Wildlife Care Center. It is advisable to always contact the Care Center at (503) 292-0304 prior to capturing and transporting any animal.
What is Audubon Society of Portland doing to address Avian Influenza: Audubon Society of Portland Staff have been in regular contact with state and federal officials working on the response plans for Avian Influenza. Our goals are as follows:
- To ensure that ecologically responsible Avian Influenza response plans are adopted.
- To promote responsible reporting on this issue in the local media.
- To ensure that sufficient monitoring of potential impacts to native North American wildlife species is instituted.
- To ensure that our Wildlife Center adopts current safety protocols to ensure safety of staff and volunteers working at our facility.
At this point in time, health officials have informed our Care Center staff that there is no need to take additional precautions beyond our standard operating procedures to protect staff and volunteers from exposure to Avian Flu. The Care Center works closely with a variety of wildlife and health agencies to monitor for disease outbreaks in local wildlife populations.
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