Avian Influenza Current Situation Summary

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Situation by Type and Location

  • CDC considers the risk to the U.S. public’s health from HPAI H5 or H7 virus outbreaks in wild birds or poultry in the United States to be low, but has developed the following interim guidance:
  • In addition, CDC recommends the following protective actions:

Protective actions around birds

  • As a general precaution, people should avoid wild birds and observe them only from a distance
  • Avoid contact with domestic birds (poultry) that appear ill or have died
  • Avoid contact with surfaces that appear to be contaminated with feces from wild or domestic birds

What to do if you find a dead bird
State and local agencies have different policies for collecting and testing birds, so check with your state health department, state veterinary diagnostic laboratory, or state wildlife agency for information about reporting dead birds in your area. Wildlife agencies routinely investigate sick or dead bird events if large numbers are impacted. This type of reporting could help with the early detection of illnesses like West Nile virus or avian influenza. If local authorities tell you to simply dispose of the bird’s carcass (body), don’t handle it with your bare hands. Use gloves or an inverted plastic bag to place the carcass in a garbage bag, which can then be disposed of in your regular trash.

To report unusual signs in birds you have seen in the wild, call 1-866-4-USDA-WS (1-866-4-8732-97).

Preparing food

  • The U.S. poultry industry maintains rigorous health and safety standards, including routine monitoring for avian influenza.
  • It is safe to eat properly handled and cooked poultry in the United States.
  • However, consumers are reminded to handle raw poultry hygienically and cook all poultry and poultry products (including eggs) thoroughly before eating.
  • Raw poultry can be associated with many infections, including salmonella.
  • While there is no evidence that any human cases of avian influenza have ever been acquired by eating properly cooked poultry products, uncooked poultry and poultry products (like blood) have been linked to human infections with organisms other than influenza. Proper cooking kills influenza viruses. Visit the USDA food safety website at USDA – Food Safety EducationExternal for instructions on handling poultry safely.

Traveling to other countries

  • Currently, CDC does not recommend any travel restrictions to any of the countries affected by avian influenza viruses in poultry or people.
  • CDC does recommend that travelers to countries with avian influenza A outbreaks in poultry or people observe the following:
    • Avoid visiting poultry farms, bird markets and other places where live poultry are raised, kept, or sold.
    • Avoid preparing or eating raw or undercooked poultry products.
    • Practice hygiene and cleanliness.
    • Visit a doctor if you become sick during or after travel.
  • CDC Travelers’ Health for more information on avian influenza.

If you’ve had direct contact with infected birds

  • People who have had direct contact with infected bird(s) should be watched if they become ill. They may be given influenza antiviral drugs to prevent illness.
  • While antiviral drugs are most often used to treat flu, they also can be used to prevent infection in someone who has been exposed to influenza viruses. When used to prevent seasonal influenza, antiviral drugs are 70% to 90% effective.
  • Close contacts (family members, etc.) of people who have been exposed to avian influenza viruses are being asked to monitor their health and report any flu-like symptoms.

If you’re a clinician, laboratorian or public health worker

Avian Influenza: Information for Health Professionals and Laboratorians for the latest guidance.

Background

Avian influenza refers to disease caused by infection with avian (bird) influenza (flu) Type A viruses. Avian influenza A viruses can infect the respiratory and gastrointestinal tract of birds and have been isolated from more than 100 different species of wild birds around the world. Aquatic birds including gulls, terns, and shorebirds, and waterfowl such as ducks, geese and swans are considered reservoirs (hosts) for avian influenza A viruses. Some avian influenza A viruses can infect domestic poultry, and outbreaks of avian influenza in domestic poultry occur worldwide.  For more information: World Organisation for Animal Health (OIE) Avian Influenza PortalExternal and the World Animal Health Information DatabaseExternal. Some avian influenza A viruses have infected other animal species, and sporadic human infections with some avian influenza A viruses have occurred.

Classification of Avian Influenza A Viruses

Avian influenza A viruses are classified into two categories: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI) based on their molecular characteristics and their ability to cause disease and mortality in chickens in a laboratory setting. For more information: OIE Terrestrial Animal Health Code, Infection with Avian Influenza VirusesExternal and PDF Cdc-pdf[227 KB, 6 pages]External

Both HPAI and LPAI viruses can spread rapidly in wild birds and poultry. Most avian influenza A viruses circulating among wild birds and poultry are classified as LPAI A viruses and typically cause asymptomatic infection to mild illness.  HPAI viruses can cause severe disease and high mortality in infected wild birds and poultry. Whether a virus is classified as a LPAI or HPAI virus applies to the ability to cause disease in infected poultry, and does not refer to whether it causes disease in humans. Both LPAI and HPAI virus infections of humans have resulted in a wide spectrum of illness, from mild to severe and fatal.

 

Examples of Avian Influenza A Virus Infections in Wild Birds in the U.S.

  • The U.S. Department of Interior (DOI) and the United States Department of Agriculture (USDA) are the lead federal agencies for outbreak investigation and control in wild birds and the USDA is the lead agency for such activities in domestic birds. CDC coordinates with DOI, USDA and with state health departments on appropriate public health measures and works with animal health colleagues to minimize the public health risk posed by avian influenza A viruses.
  • In December 2014 and January 2015, the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) reported the presence of highly pathogenic avian influenza (HPAI) H5N2 and HPAI H5N8 viruses in wild birds Cdc-pdf[156 KB, 3 pages]External in a few states. The initial findings were a result of increased outreach, reporting and surveillance activities following the detection of HPAI H5N2 among commercial flocks in CanadaExternal reported in early December 2014. Two of these viruses were then detected commercial poultry in the United States.
  • In January 2015, an HPAI* H5N1 virus was detected in a wild duck in the United States. The H5N1 virus isolated from a U.S. wild bird was a new mixed virus (a reassortant) that was genetically different from the Asian avian H5N1 viruses that have caused human infections associated with high mortality in several other countries (notably in Asia and Egypt).
  • CDC considers the risk to people from these HPAI infections in wild birds to be low, but has developed interim guidance on testing and chemoprophylaxis. For more information, see the “Protective Actions You Can Take” tab at the top of this page.
  • No human infections with these viruses have been detected at this time. However, similar viruses have infected people in the past. It’s possible that human infections with these viruses may occur.

Global Situation:

Background: Outbreaks of avian influenza among poultry occur periodically worldwide. For more information: World Organization for Animal Health (OIE’s) World Animal Health Information Database (WAHID)External, OIE’s WAHID Handistatus IIExternal, the U.S. Department of Agriculture’s (USDA’s) Avian Influenza Outbreaks in the United States Q&A Cdc-pdf[160 KB, 3 pages]External, and CDC’s Outbreaks of Avian Influenza in North America. CDC coordinates with, the World Health Organization and other international partners to minimize the public health risk posed by avian influenza A viruses.

Examples of Poultry Outbreaks of Avian Influenza Worldwide:

H5 viruses (HPAI):

  • Since December 2003, Asian-lineage highly pathogenic avian influenza (HPAI) A(H5N1) viruses have caused high mortality in infected poultry and wild birds in Asia, the Middle East, Europe and Africa.
    • Millions of poultry have been culled to control the spread of HPAI H5N1 viruses.
  • As of 2011, the United Nations Food and Agriculture Organization considered six countries to be endemic for HPAI H5N1 virus in poultry: Bangladesh, China, Egypt, India, Indonesia, and Vietnam.
    • Outbreaks of HPAI H5N1 virus have also occurred among poultry in non-endemic countries.
    • Outbreaks of HPAI H5N1 virus among poultry continue to occur in some countries.
  • Since 2012, an increasing number of countries have reported detection of HPAI viruses of additional H5 subtypes different from H5N1, such as H5N2, H5N3, H5N5, H5N6, H5N8External and H5N9, among wild birds and/or domestic poultry.
  • Beginning in January 2015 to June 2015, HPAI (H5) virus outbreaks (including H5N2 and H5N8 viruses) were reported in commercial poultry flocks in 21 U.S. states and Canada. More information is available at CDC’s H5 Viruses in the United States page and from the USDA Animal and Plant Health Inspection Service’s (APHIS’s) HPAI 2014/15 Confirmed DetectionsExternal page.
  • During 2016 and early 2017, there were outbreaks of HPAI H5N8 virus in domestic poultry and wild birds in Europe, Asia and parts of Africa.
  • With the exception of HPAI H5N1 and HPAI H5N6 viruses, none of these other HPAI H5 viruses are known to have caused illness in people to date.

H7 viruses (HPAI and LPAI):

  • There have been outbreaks of HPAI H7 viruses identified in poultry in various countries, including Mexico, the Netherlands, Chile and Canada. Sporadic cases of human infection with these viruses have been identified.
  • Since 2013, Asian lineage LPAI A(H7N9) viruses in China have been detected in poultry or live poultry markets in eastern, southern and northern China. LPAI H7N9 virus infection does not generally cause observable illness in poultry.  Note: These viruses have caused severe illness and death in people.
  • Asian Lineage LPAI H7N9 viruses have been circulating among poultry without causing signs of illness in infected birds in China since 2013. These viruses also have caused human infections. In early 2017, Asian Lineage HPAI A(H7N9) virus infection of humans was reported in southern China, suggesting that some Asian Lineage LPAI H7N9 virus strains have evolved to become HPAI H7N9 viruses. These Asian Lineage HPAI H7N9 viruses could cause illness and death in infected poultry, and can cause severe illness and fatal outcomes in infected humans.
  • To date, Asian lineage LPAI and HPAI H7N9 viruses reported in China have not been detected in poultry, wild birds, or humans in the United States.

Examples of Poultry Outbreaks of Avian Influenza in the United States

  • Both HPAI and LPAI outbreaks occur among poultry from time to time in the United States. The United States Department of Agriculture (USDA)External is the lead federal agency for outbreak investigation and control in domestic birds.
  • CDC coordinates with USDA and state health departments on appropriate public health measures and works with animal health colleagues to minimize public health risk posed by avian influenza A viruses.

H5 viruses (HPAI):

  • Between 1997 and 2014, based on the World Organisation for Animal Health (OIE)External reporting criteria for avian influenza in commercial poultry, the United States experienced one outbreak of HPAI H5N2 virus in Texas in 2004 that was restricted to one poultry farm.
    • The February 2004 Texas 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.
  • Beginning in January 2015 to June 2015, HPAI (H5) virus outbreaks (including H5N2 and H5N8 viruses) were reported in commercial poultry flocks in 21 U.S. states and Canada. More information is available at CDC’s H5 Viruses in the United States page and from the USDA Animal and Plant Health Inspection Service’s (APHIS’s) HPAI 2014/15 Confirmed DetectionsExternal page.
  • Note: no human infections with any HPAI H5 viruses, including HPAI H5N2 or H5N8 virus, have been identified to date.

H7 viruses (HPAI and LPAI):

Avian Influenza A Virus Infection of Humans

Avian influenza A viruses do not normally infect people, but sporadic infections in people have occurred with some avian influenza A viruses. Illnesses in humans from avian influenza A virus infections have ranged in severity from asymptomatic to mild to severe and fatal disease. Human infections with avian influenza A viruses have most often occurred after contact with infected birds or their secretions or excretions. Three subtypes of avian influenza A viruses are known to infect people (H5, H7 and H9 viruses). Among these, Asian lineage H5N1 and H7N9 have caused the majority of infections in people.

Examples of Human Infections with Avian Influenza A viruses

H5 viruses:

H7 viruses:

  • H7 virus infection in humans is uncommon, but has been documented, mostly among people who had direct contact with infected birds, especially during outbreaks of H7 virus among poultry.
  • Sporadic human infections with avian influenza A (H7) viruses (low pathogenic avian influenza “LPAI” H7N2, H7N3, H7N7, H7N9) and (HPAI H7N3, H7N7, H7N9) have been identified in a number of countries, including the United States, Canada, Mexico, the Netherlands, the United Kingdom, Taiwan, Malaysia, and China.  Both LPAI and HPAI H7 virus infections have resulted in a wide spectrum of illness in infected persons, ranging from asymptomatic to mild illness (e.g., conjunctivitis, upper respiratory tract illness) to severe pneumonia, multi-organ failure, with fatal outcome.
  • Asian Lineage low pathogenic avian influenza A (H7N9) viruses
  • North American lineage low pathogenic avian influenza A (H7N2) virus

H9 viruses:

  • Rare, sporadic LPAI H9N2 virus infections of humans have been reported in several countries (China, Bangladesh, Egypt), most commonly in children. LPAI H9N2 virus infection generally causes mild upper respiratory tract illness, but pneumonia was reported in an immunosuppressed adult and one fatal outcome was reported in China.

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Page last reviewed: March 17, 2015
Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)