Bird Flu | Center for Health and Health in Schools

Updated May 2012

Introduction

Avian flu, also known as “bird flu”, is not a current threat in the United States but is a potential concern due to outbreaks, primarily in Asian countries, during the past few years. The US government recently invested in research to develop vaccines to protect humans against the more virulent strains of avian flu. The Center for Health & Health Care in Schools has developed this fact sheet that summarizes recent developments as well as recommendations from theCenters for Disease Control and Prevention (CDC) and the World Health Organization (WHO) for responding to future outbreaks.

Avian flu is an infectious disease caused by viruses that infect birds, and less commonly, pigs.¹ The first documented infection of humans with an avian influenza virus occurred in Hong Kong in 1997, when the influenza A virus, H5N1 strain, caused severe respiratory disease in 18 humans, and resulted in six deaths.² The infection of humans happened at the same time and with the same strain that was infecting Hong Kong’s bird population. The investigation sparked by this outbreak of avian flu determined that close contact with live infected poultry was the source of human infection and that the virus had jumped directly from birds to humans.³ From January 2004 to October 10, 2005, there have been 117 cases of human H5N1 infections. Sixty have been fatal.⁴ Human cases have occurred in Cambodia, Indonesia, Thailand, and Vietnam in the current outbreak. Previous outbreaks, in 1997 and 2003, have occurred in Hong Kong and China.⁵

This fact sheet summarizes what is known about avian flu; describes recommendations for health care providers, consumers, and travelers; and includes links to resources about avian flu.

Avian Flu Facts⁶

All bird species are thought to be susceptible to viral infection; however, domestic poultry flocks are especially vulnerable to infections that can rapidly reach epidemic proportions.
Only influenza A viruses infect birds and the disease occurs in two forms- “high pathogenicity” and “low pathogenicity”. The “highly pathogenic” or contagious form is of great concern because it is extremely contagious in birds and rapidly fatal. Viruses with “low pathogenicity” can, over time, mutate into highly pathogenic viruses.
There are 15 subtypes of influenza A virus. Influenza A strain H5N1 is of primary concern because it has caused the most severe outbreaks, although strains H9N2 and H7N7 as well as several other strains have also caused illness in humans.

How is avian flu spread among birds?⁷

Infected birds shed flu virus in their saliva, nasal secretions, and feces.
Fecal-to-oral transmission is the most common mode of spread between birds.

How does avian flu affect humans?⁸

Avian flu viruses do not usually infect humans, but there have been several instances of human infections and outbreaks of avian flu since 1997.
Most cases of avian flu in humans are thought to have resulted from human contact with infected poultry or contaminated surfaces.
Other possible environmental methods of contamination to humans are oral digestion of contaminated water while swimming and widespread use of untreated poultry feces as fertilizer.⁹

Can avian flu be transmitted from person-to-person?¹⁰

Person-to-person transmission has occurred; however, it is rare and should not be cause for alarm. However, according to the WHO, the risk of a global outbreak, or pandemic, is serious.
The WHO notes that “with the H5N1 virus now firmly entrenched in large parts of Asia, the risk that more human cases will occur will persist. Each additional human case gives the virus an opportunity to improve its transmissibility in humans, and thus develop into a pandemic strain. While neither the timing nor the severity of the next pandemic can be predicted, the probability that a pandemic will occur has increased.”

What are the symptoms of avian flu in humans?¹¹

The reported symptoms of avian flu range from typical flu-like symptoms (fever, cough, sore throat, and muscle aches) to eye infections.
Pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications have also been reported as symptoms.
Diarrhea, vomiting, abdominal pain, and bleeding from the nose and gums have been reported early in the course of illness as well.¹²

How is avian flu diagnosed?

Testing for avian flu (H5N1) is indicated for hospitalized patients with:

Severe acute respiratory illness in countries with H5N1 avian flu, particularly in patients who have been exposed to poultry, as well as in cases of serious unexplained illness such as encephalopathy or diarrhea.
History of travel within 10 days of symptom onset to a county with documented H5N1 avian flu in poultry and/or humans.¹³

How is avian flu treated?¹⁴

There are several different influenza antiviral drugs that can be used to treat pneumonia caused by the avian flu. They are amantadine, rimantadine, oseltamivir, and zanamivir.
All four of these drugs have an affect on influenza A viruses, but some of the strains have become resistant to these drugs.
In 2004, it was found that H5N1 viruses, which had been isolated from poultry and humans in Asia, were resistant to both amantadine and rimantadine. This has led to the ongoing monitoring of avian viruses for resistance of influenza antiviral medications.

Are there any vaccines available for avian flu?¹⁵

As noted previously, a rising concern is that the avian and human flu viruses can exchange genes when a person is simultaneously infected with viruses from both species, which can give rise to a new subtype of the flu virus.
If a new flu virus emerges, it is possible that few humans would have natural immunity and existing vaccines would not be effective against this new subtype. Therefore, the NIH suggests that preparedness efforts be continued because of the possibility of an avian flu pandemic.
The National Institute of Allergy and Infectious Diseases (NIAID), a section of the National Institutes of Health (NIH), has awarded contracts to Aventis Pasteur Inc. and Chiron Corporation to support the production of a vaccine for avian flu (H5N1). Additionally, NIAID has agreed to partner with MedImmune, Inc. to research and develop vaccines against influenza strains, including H5N1 avian flu virus.¹⁶

What are some recommendations for avian flu?

Due to the fact that the avian flu can be transmitted from infected poultry to humans, the CDC has issued a series of interim recommendations for the following groups in the U.S.:

Health Care Professionals ¹⁷

Providers should be alert for any respiratory illness in individuals who may have been in contact with infected poultry.
Health care providers should pay careful attention to hand hygiene before and after patient contact (gloves, gowns, eye wear), especially if they are treating a suspected case of avian flu.
If caring for a suspected case of avian flu, providers should place the patient in an isolation room to prevent others from becoming exposed.

Consumer Food Safety Guidance ¹⁸

No evidence has been shown that avian flu is spread by eating contaminated poultry or poultry products. Influenza viruses, like many food borne pathogens, are usually destroyed by adequate heat.
Consumers should cook all poultry and poultry products thoroughly before eating (above 180° F).
Raw poultry should be handled carefully. Therefore, all utensils and surfaces that come in contact with raw poultry should be cleaned well after preparation.

Travelers ¹⁹

The CDC does not recommend the avoidance of travel to countries affected by avian flu, but has given recommendations for those who are planning to travel to infected regions.

Before any international travel to an area affected by avian flu:

Travel with a first aid kit that has a thermometer and an alcohol based hand rub for hand hygiene.
Become educated about the avian flu disease risks and CDC health recommendations by visiting http://www.cdc.gov/flu/avian/index.htm.
Be up-to-date on vaccinations and visit your doctor 4 to 6 weeks prior to travel.
Identify in-country health care resources in advance of your trip.

During travel to an affected area:

If traveling to an area that has a known avian flu outbreak try to avoid areas that contain live poultry, especially live animal markets and poultry farms.
Do not eat any raw or undercooked poultry products.
Wash your hands carefully and frequently to remove infectious material from your skin.
If you become sick with symptoms, seek medical services and inform your health care provider of possible exposure.

After your return from an infected area:

Monitor your health for 10 days.
If an illness develops within 10 days consult your health care provider. It is important to alert your provider that you have recently traveled to an area that has a known avian flu outbreak.

For additional information, visit the following sites:

Hand Hygiene:

http://www.cdc.gov/handwashing/

Cleaning of items:
http://www.cdc.gov/ncidod/op/_resources/OOP%20Brochure%2012.20.05.pdf

Guidance for protecting workers against avian flu:
www.osha.gov/dsg/guidance/avian-flu.html

Vaccine Research:
www3.niaid.nih.gov/news/newsreleases/2005/medimmune.htm

REFERENCES:
¹World Health Organization. Avian influenza frequently asked questions. October 2005. Available at http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/index.html. Accessed October 2005.
²National Institutes of Health. Focus on the flu: Timeline. Available at http://www3.niaid.nih.gov/news/focuson/flu/default.htm. Accessed October 2005.
³World Health Organization. Avian influenza – a fact sheet. January 2004. Available at http://www.who.int/mediacentre/factsheets/avian_influenza/en/index.html. Accessed October 2005.
⁴Centers for Disease Control and Prevention. Recent Avian Influenza Outbreaks in Asia. Available at http://www.cdc.gov/flu/avian/outbreaks/current.htm . Accessed October 2005.
⁵Poultry outbreaks have been reported in the following countries (listed in order of reporting): The Republic of Korea, Viet Nam, Japan, Thailand, Cambodia, Lao People’s Democratic Republic, Indonesia, China, Malaysia, Russia, Kazakhstan, Mongolia, Turkey, and Romania. Japan, The Republic of Korea, and Malaysia have since been considered free of the disease due to control of outbreak. World Health Organization. Avian influenza frequently asked questions. October 2005. Available at http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/index.html. Accessed October 2005.
⁶ World Health Organization. Avian influenza – a fact sheet. January 2004. Available at http://www.who.int/mediacentre/factsheets/avian_influenza/en/index.html. Accessed October 2005.
⁷Centers for Disease Control and Prevention. Spread of Avian Influenza Viruses among Birds. October 2005. Available at http://www.cdc.gov/flu/avian/gen-info/spread.htm. Accessed October 2005.
⁸Centers for Disease Control and Prevention. Key Facts about Avian Influenza (Bird Flu) and Avian Influenza A (H5N1) Virus. May 2005. Available at http://www.cdc.gov/flu/avian/gen-info/facts.htm. Accessed October 2005.
⁹Beigel JH, Farrar J, Han AM, Hayden FG, Hyer R, de Jong MD, Lochindarat S, Tien NTK, Hien TT, Nicoll A, Touch S, Yuen KY. Avian Influenza A (H5N1) in Humans. NEJM, 2005; 353(13):1374-1385.
¹⁰World Health Organization. Avian influenza frequently asked questions. October 2005. Available at http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/index.html. Accessed October 2005.
¹¹Centers for Disease Control and Prevention. Key Facts about Avian Influenza (Bird Flu) and Avian Influenza A (H5N1) Virus. May 2005. Available at http://www.cdc.gov/flu/avian/gen-info/facts.htm. Accessed October 2005.
¹² Beigel JH, Farrar J, Han AM, Hayden FG, Hyer R, de Jong MD, Lochindarat S, Tien NTK, Hien TT, Nicoll A, Touch S, Yuen KY. Avian Influenza A (H5N1) in Humans. NEJM, 2005; 353(13):1374-1385.
¹³Centers for Disease Control and Prevention. Update: Human Infection with Avian Influenza A (H5N1) Virus in Asia. October 2005. Available at http://www.cdc.gov/travel/other/avian_influenza_se_asia_2005.htm. Accessed October 2005.
¹⁴Centers for Disease Control and Prevention. Avian influenza infection in humans. May 2005. Available at http://www.cdc.gov/flu/avian/gen-info/avian-flu-humans.htm. Accessed October 2005.
¹⁵National Institutes of Health. NIH News. NIAID announces contracts to develop vaccine against H5N1 avian influenza. May 2004. Available at http://www.nih.gov/news/pr/may2004/niaid-27.htm. Accessed October 2005.
¹⁶National Institute of Allergy and Infectious Diseases. HHS News. NIAID and MedImmune join forces to develop potential pandemic influenza vaccines. September 2005. Available at www3.niaid.nih.gov/news/newsreleases/2005/medimmune.htm. Accessed October 2005.
¹⁷Center for Disease Control and Prevention. Interim recommendations for persons with possible exposure to avian influenza during outbreaks among poultry in the United States. February 2004. Available at http://www.cdc.gov/flu/avian/professional/possible-exposure.htm. Accessed October 2005.
¹⁸Ibid.
¹⁹Centers for Disease Control and Prevention. Update: Human Infection with Avian Influenza A (H5N1) Virus in Asia. October 2005. Available at http://www.cdc.gov/travel/other/avian_influenza_se_asia_2005.htm. Accessed October 2005.