H5N1 Arrives in the United States

Jan 30, 2015 | Colleen Nguyen | Outbreak News

As of January 16, 2015, Avian Influenza H5N1 has officially arrived in the United States. H5N1, a flu strain known to be highly pathogenic -- that is, known to have a superior ability to produce disease in a host -- was discovered in an American green-winged teal duck in Whatcom County, Washington [1, 2, 4].

What is H5N1?

A sub-type of influenza virus, H5N1 is known to cause exceptionally infectious and severe respiratory disease, primarily in birds [5]. Historically, H5N1 has wreaked havoc with serious outbreaks among birds in parts of Asia and the Middle East. These outbreaks have often led to cullings of commercial flocks across the globe, with import bans and substantial economic impacts [3]. While H5N1 does not generally infect humans, human cases do exist and there have been approximately 650 reported human cases of H5N1 across fifteen countries, since 2003 [3]. Of those 650 reported human cases, roughly 400 have ended in death, translating to a 60% mortality rate [3, 5]. Those infected with H5N1 often work directly with poultry, which places them at higher risk of infection due to the nature of close contact and influenza transmission [3]. However, sustained human-to-human transmission of H5N1 remains rare [3]. Symptoms of H5N1 include: fever and cough, shortness of breath, acute respiratory distress, and abdominal pain -- complications arising from H5N1 can include pneumonia, respiratory failure, and shock [3].  

The Silver Lining: Influenza Strain Variation

While the arrival of H5N1 in the United States may not be entirely positive news, there exists a silver lining to its discovery. The H5N1 strain detected in Washington is genetically different from the H5N1 strain circulating in Asia and the Middle East [6]. According to the United States Geological Survey, this variation contains genes from North American waterfowl viruses and appears to be a combination of H5N1 and H5N8 [7]. The reassortment of influenza virus was not unexpected, as influenza viruses reassort regularly in circulation and there exist hundreds of strains of influenza [2].

Precautionary Measures

Although this particular strain of H5N1 has not infected people or domestic poultry within the United States, there are precautionary measures that can be taken to protect yourself from potential transmission and infection. These precautions include: avoiding dead or sick birds, abstaining from visiting live poultry markets, and keeping away from those who may potentially be infected with H5N1 [3]. H5N1 cannot be transmitted through the consumption of “properly handled and cooked poultry and eggs” [3].


[1] http://www.cidrap.umn.edu/news-perspective/2015/01/usda-confirms-high-path-h5n1-washington-state  

[2] http://www.promedmail.org/direct.php?id=20150122.3109001

[3] http://www.flu.gov/about_the_flu/h5n1/

[4] http://www.tulane.edu/~wiser/protozoology/notes/Path.html

[5] http://www.who.int/influenza/human_animal_interface/avian_influenza/h5n1_research/faqs/en/

[6] http://www.nbcnews.com/health/health-news/new-bird-flu-found-u-s-duck-first-time-n291781

[7] http://www.usgs.gov/newsroom/article.asp?ID=4108#.VMoyl2jF-Sr

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