Avian Influenza Current Situation
|Wild Birds Worldwide|
- Avian influenza A viruses have been isolated from more than 100 different species of wild birds from around the world. Most of these viruses were low pathogenic avian influenza A viruses.
- The majority of these wild birds have been aquatic birds, including gulls, terns, and shorebirds, or waterfowl such as ducks, geese and swans. These wild birds are considered reservoirs (hosts) for avian influenza A viruses.
- Around the world, avian influenza A outbreaks occur among poultry from time to time.
- Currently, highly pathogenic avian influenza (HPAI) A (H5N1) virus is considered endemic among poultry in six countries (Bangladesh, China, Egypt, India, Indonesia, and Vietnam). This means the virus is commonly found in poultry in those countries. Sporadic outbreaks have occurred among poultry in other countries.
|Poultry in North America|
- Low pathogenic avian influenza A outbreaks occur among poultry from time to time in North America.
- Since 1997, based on the World Organization for Animal Health (OIE) reporting criteria for avian influenza in commercial poultry, the United States has experienced one outbreak of highly pathogenic avian influenza A (H5N2) virus in poultry that was restricted to one poultry farm.
- See Past Outbreaks of Avian Influenza in North America for more information about low pathogenic outbreaks and one highly pathogenic outbreak in poultry.
|Humans in North America|
- Avian influenza A viruses in humans in North America have very rarely been identified.
- Avian influenza A viruses have caused relatively mild to moderate illness in humans in North America.
- No HPAI H5N1 viruses have ever been identified in humans, poultry, wild birds or other animals in the United States.
- See Past Outbreaks of Avian Influenza in North America for more information.
For U.S. Travelers to Other Countries
- Currently, CDC does not recommend any travel restrictions to any of the countries affected by highly pathogenic avian influenza (HPAI) A (H5N1) virus in poultry.
- CDC does recommend that travelers to HPAI H5N1-endemic countries and those countries experiencing HPAI H5N1 poultry outbreaks 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
- See CDC Travelers’ Health for more information.
For Health Professionals Practicing in the United States
- Avian influenza A viruses have rarely caused illness in humans in North America.
- To date, there have not been any reports of HPAI H5N1 virus infections among wild birds, poultry, or other animals or humans in the United States.
Highly Pathogenic Avian Influenza (HPAI) A (H5N1)
- Worldwide, the epidemiology of human infections with HPAI H5N1 virus has not changed significantly since the re-emergence of human cases of HPAI H5N1 virus infection in 2003.
- CDC continues to recommend that surveillance for suspected human cases of HPAI H5N1 virus infection in the United States remain at an enhanced level.
- Successful identification of cases depends upon health care providers obtaining information from patients who present with respiratory illness about their recent travel outside of the U.S. and their activities while traveling.
- Clinicians should consider HPAI H5N1 virus infection as well as seasonal influenza virus infection in returning travelers presenting with respiratory illness.
- CDC recommends that health care providers consider HPAI H5N1 testing for persons that have both a clinical syndrome consistent with HPAI H5N1 disease and relevant possible exposure to HPAI H5N1 virus during the 7 days before the person’s illness onset. The state health department should be contacted first, regarding a patient with suspected H5N1 and testing for H5N1 virus infection.
- The most common clinical syndrome is fever and cough which in some patients progresses rapidly to several viral pneumonia with shortness of breath, difficulty breathing, and hypoxia. 1,2
- Frequent complications include respiratory failure, acute respiratory distress syndrome (ARDS), multi-organ failure, and death.3
- Relevant exposures in the 7 days prior to illness onset include the following: direct contact or very close contact with sick or dead poultry known or highly suspected to be infected with HPAI H5N1 virus, or visiting a live poultry market where poultry are known to be infected with HPAI H5N1 virus, or very close contact with a severely ill confirmed H5N1 patient.
Interim Guidance Documents Specific to HPAI H5N1
Vaccination and Treatment for HPAI H5N1 in Humans
- HPAI H5N1 vaccine is being stockpiled for pandemic preparedness by the United States government. It is not currently available for use. It could be used if an HPAI H5N1 virus begins transmitting easily and efficiently from person to person.
- Oseltamivir remains the primary recommended antiviral drug for treatment and chemoprophylaxis for HPAI H5N1.
When to Contact CDC
- The Influenza Division, CDC, should be contacted immediately for the following things:
- Any positive results of HPAI H5N1 virus testing.
- Any questions related to HPAI H5N1 and specimen collection, laboratory testing, antiviral treatment, or infection control.
- Laboratory results for human clinical specimens that test positive for HPAI H5N1 virus by reverse transcription-polymerase chain reaction (RT-PCR) at a laboratory in the United States should be confirmed immediately at the Influenza Division, National Center for Immunization and Respiratory Diseases, CDC, a designated WHO H5 Reference Laboratory located in Atlanta, Georgia.
- Before sending specimens, state and local health departments should contact the CDC Influenza Division Epidemiology and Prevention Branch at (404) 639-3747 (Monday – Friday, 8:30 AM - 5:00 PM or the on-call epidemiologist at (770) 488-7100 (all other times).
- CDC supports USDA’s Animal and Plant Health Inspection Service in its ongoing regulations to prohibit or restrict the importation of birds, poultry, and unprocessed birds and poultry products (such as eggs and feathers) from countries where highly pathogenic avian influenza (HPAI H5N1) has been confirmed in poultry. Visit Bringing a Bird into the United States for more information.
- Writing Committee of the Second World Health Organization Consultation on Clinical Aspects of Human Infection with Avian Influenza A (H5N1) Virus, Abdel-Ghafar AN, Chotpitayasunondh T, Gao Z, Hayden FG, Nguyen DH, de Jong MD, Naghdaliyev A, Peiris JS, Shindo N, Soeroso S, Uyeki TM. Update on avian influenza A (H5N1) virus infection in humans. N Engl J Med. 2008 Jan 17;358(3):261-73
- Uyeki TM. Human infection with highly pathogenic avian influenza A (H5N1) virus: review of clinical issues. Clin Infect Dis. 2009 Jul 15;49(2):279-90.
- World Health Organization Clinical management of human infection with avian influenza A (H5N1) virus. Updated advice 15 August 2007 [116 KB, 22 pages]