Outbreaks of Avian Influenza in North America

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Summary

  • Avian influenza A viruses are routinely detected in wild birds. Around the world and in North America, avian influenza A outbreaks occur in poultry from time to time.
  • Outbreaks of some avian influenza A viruses in poultry have been associated with illness and death in people in Asia, Africa, Europe, the Pacific, and the Near East.
  • While very rare, some avian influenza A viruses have also caused illness in people in North America.

North American Outbreaks Among Poultry With No Known Human Infections

Low pathogenic avian influenza A (LPAI) outbreaks*

Based on the World Organization for Animal Health (WOAH) reporting criteria for avian influenza in commercial poultry, since 1997, the United States has experienced sporadic incidents of LPAI (H5 or H7).

For more information about LPAI (H5 or H7) outbreaks that have been reported in North America (including the U.S.) and around the world, visit the WOAH’s World Animal Health Information System (WAHIS). For more information about Avian influenza (H5 or H7) outbreaks that have been reported in North America (including the U.S.) and around the world prior to January 2005, visit the WOAH’s WAHIS Handistatus II.

Highly pathogenic avian influenza A (HPAI) outbreaks*

From 1997 to 2016, outbreaks of HPAI (H5) viruses in commercial poultry were reported to the WOAH. This does not include any outbreaks which may have been reported in 2017.

H5N2 in Texas, 2004

In February 2004, an outbreak of HPAI (H5N2) virus was reported in a flock of 7,000 chickens in south-central Texas. At that time, this was the first outbreak of HPAI in the United States in 20 years.1,2 No transmission of HPAI (H5N2) virus to humans was reported.

H5 Outbreaks, 2014-2015

Beginning in January 2015 to June 2015, HPAI (H5) virus outbreaks were reported in commercial poultry flocks in 21 U.S. states and Canada. HPAI viruses also were detected in captive and wild birds in 2014 and 2015 in the U.S. and Canada. No transmission of HPAI (H5) virus to humans was reported.

More information about H5 outbreaks in birds and poultry in the U.S. during 2014-2015 is available at H5 Viruses in the United States.

H7N8 in Indiana, 2016

In January 2016, an outbreak of HPAI (H7N8) virus was reported in a commercial turkey flock in Dubois County, Indiana. LPAI (H7N8) was subsequently detected in eight nearby turkey flocks. No transmission of HPAI (H7N8) or LPAI (H7N8) virus to humans was reported. More information is available at Avian Influenza H7N8 Update.

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North American Avian Influenza Viruses Associated With Human Infections

Outbreaks of some avian influenza viruses (mostly among poultry) have been associated with infection in people in Asia, Africa, Europe, the Pacific, and the Near East. While very rare, avian influenza A viruses also have caused illness in people in North America.

H7N2 in Virginia, 2002

In 2002, a person involved with culling activities developed influenza-like illness when a low pathogenic avian influenza A (LPAI) (H7N2) outbreak occurred among commercial turkey and chicken flocks in Virginia. Serological testing confirmed infection with avian influenza A (H7N2) virus; no human-to-human transmission was evident and the person made a full recovery.5,7

H7N2 in New York, 2003

In November 2003, a case of avian influenza A virus infection was detected in an adult male from New York, who was hospitalized for respiratory tract illness. LPAI H7N2 virus was isolated from a respiratory specimen from the patient. The patient’s acute symptoms resolved and there was no evidence of human-to-human transmission. The source of this person’s infection is unknown.5,6

H7N3 in Canada, 2004

On February 19, 2004, the Canadian Food Inspection Agency announced an outbreak of avian influenza A (H7N3) in poultry in the Fraser Valley region of British Columbia. Culling operations and other measures were performed in an effort to control the spread of the virus. This was initially a LPAI outbreak that evolved into an HPAI outbreak. Health Canada reported two cases of laboratory-confirmed influenza A (H7): one in a person involved in culling operations on March 13-14, and the other in a poultry worker who had close contact with infected poultry on March 22-23. Both patients developed conjunctivitis (eye infection) and mild illness. Their illnesses resolved after treatment with the antiviral medication oseltamivir.3,4

Although these are the only laboratory-confirmed cases of avian influenza A (H7) in humans during this outbreak in Canada, approximately 10 other poultry workers exhibited conjunctival and/or upper respiratory symptoms after having contact with infected poultry. Use of personal protective equipment is mandatory in Canada for all persons involved in culling activities, and compliance with prescribed safety measures is monitored. For more information about this outbreak, visit the Canadian Food Inspection Agency’s website.

H7N2 in New York, 2016

In December 2016, CDC became aware of an outbreak of low pathogenic avian influenza A (H7N2) virus (LPAI H7N2) among cats in animal shelters in New York City. One human infection was detected in a person who had close, prolonged, unprotected exposure to the respiratory secretions of H7N2 infected, sick cats at an affected shelter.  No human-to-human transmission was evident and the person made a full recovery. Additional information on influenza in cats can be found here and a web spotlight on the avian influenza A (H7N2) outbreak in cats in animal shelters in New York City can be found here.

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References

  1. Lopez-Martinez I,Balish A, Barrera-Badillo G, et al. Highly pathogenic avian influenza A(H7N3) virus in poultry workers, Mexico, 2012.Emerg Infect Dis. 2013;19(9):1531-4. doi: 10.3201/eid1909.130087.
  2. Pelzel AM, McCluskey BJ, Scott AE. Review of the highly pathogenic avian influenza outbreak in Texas, 2004. J Am Vet Med Assoc. 2006 Jun 15;228(12):1869-75.
  3. Lee CW, Swayne DE, Linares JA, et al. H5N2 avian influenza outbreak in Texas in 2004: the first highly pathogenic strain in the United States in 20 years? J Virol. 2005 Sep;79(17):11412-21.
  4. Skowronski DM, Tweed SA, Petric M, et al. Human illness and isolation of low-pathogenicity avian influenza virus of the H7N3 subtype in British Columbia, Canada. J Infect Dis. 2006 Mar 15;193(6):899-900.
  5. Tweed SA, Skowronski DM, David ST, et al. A. Human illness from avian influenza H7N3, British Columbia. Emerg Infect Dis. 2004 Dec;10(12):2196-9.
  6. CDC. Update: Influenza Activity — United States and Worldwide, 2003—04 Season, and Composition of the 2004—05 Influenza Vaccine. MMWR 2004; 53(25).
  7. Ostrowsky B, Huang A, Terry W, et al. Low Pathogenic Avian Influenza A (H7N2) Virus Infection in Immunocompromised Adult, New York, USA, 2003. Emerg Infect Dis. 2012 Jul;18(7):1128-31.
  8. Edwards LE, Terebuh P, Adija A, et al. Serological diagnosis of human infection with avian influenza A (H7N2) virus [Abstract 60, Session 44]. Presented at the International Conference on Emerging Infectious Diseases 2004, Atlanta, Georgia, February 22–March 3, 2004.

Footnotes

*Avian influenza A viruses are designated as highly pathogenic avian influenza (HPAI) or low pathogenicity avian influenza (LPAI) based on molecular characteristics of the virus and the ability of the virus to cause disease and mortality in chickens in a laboratory setting.

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