| National Wildlife Rehabilitators Association |
| Avian Influenza |
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Special Feature: Frequently Asked Questions on Avian InfluenzaCompiled by Erica A. Miller, DVM(originally printed in The Wildlife Rehabilitator, Volume 6, Issue 1, Winter 2006) Q: What is Avian Influenza? A: Avian Influenza (AI) is usually a non-clinical infection of wild birds, caused by a group of viruses known as type A influenza. The virus has many subtypes that are identified by the two types of antigens found on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 16 different H types [H1 through H16] and 9 different N types [N1 through N9] of avian influenza virus. Avian influenza viruses are further divided into low pathogenic and highly pathogenic viruses based on the level of mortality observed in infected domestic poultry. Only those viruses that are either H5 or H7 subtypes are known to be highly pathogenic avian influenza viruses. These are the two strains of most concern for domestic birds, and for their potential to infect humans. Wild birds (primarily waterfowl and shorebirds) are the natural reservoir (or carrier) of the low pathogenic strains of the virus (LPAI). Although reservoir birds typically do not develop any clinical signs due to LPAI virus, the virus may cause disease outbreaks in domestic chickens, turkeys and ducks. Highly pathogenic avian influenza (HPAI) is a virulent and highly contagious viral disease that occurs in poultry and other birds; 100% mortality may been seen in susceptible flocks. It was first identified in Italy in the early 1900s. On rare occasions, highly pathogenic avian influenza can spread to humans and other animals, usually following direct contact with infected birds. Q: What are signs of Avian Influenza in birds? A: Clinical signs of LPAI in poultry consist primarily of mild respiratory disease, depression, and decrease in egg production in laying birds; in most cases, however, no clinical signs occur. In the few known cases of LPAI in wild birds, clinical signs are similar. The main clinical signs of HPAI in poultry are depression, loss of appetite, decreased egg production, nervous signs, swelling and blue discoloration of combs and wattles due to disturbance of blood circulation, coughing, sneezing, and diarrhea. Sudden death can occur without any previous signs. The mortality rate may reach up to 100% depending on the species of bird infected, their age, the virus type involved, and environmental factors like concurrent bacterial infections. The incubation period for these viruses ranges from as short as a few hours to three days in individual birds and up to 14 days to spread throughout a flock. Q: Is there any information on other species that have/get AI? If so, what type is it? Is there much known about how AI affects passerines, raptors, or other groups of birds? A: The majority of wild birds that historically were known to get or carry AI are waterfowl, shorebirds, terns, and occasionally upland game birds. This virus is typically LPAI. Prior to 2002, the only report of HPAI causing mortality in wild birds occurred in South Africa in 1961 when a colony of common terns died due to HPAI (H5N3) (Friend 1999). In 2002, a report suggests that a strain of H5N1 killed non-domestic birds in parks and a zoological collection in Hong Kong, including waterfowl, greater flamingos (Phoenicopterus roseus), gray herons (Ardea cinerea), and egrets. Since then, HPAI H5N1 virus was identified in only a few wild birds in Hong Kong: January 2004, peregrine falcon (Falco peregrinus) (found dead); November 2004, grey heron (found dead); December 2004, grey heron (observed sick, found dead next day); and in 2005, H5N1 was isolated from a Chinese pond heron (Ardeola bacchus) (found dead). Because Hong Kong does not have HPAI H5N1 in its domestic poultry populations and due to their active surveillance, the US considers Hong Kong AI-free. In the summer of 2005, over 6000 dead birds were found at Qinghai Lake in China. H5N1 was isolated from some of those birds, mainly bar-headed geese (Anser indicus). The current HPAI H5N1 strain in Asia has caused mortality in over 40 species of wild birds, including bar-headed geese, ducks, great black-headed gulls (Larus ichthyaetus), brown-headed gulls (Larus brunnicephalus), storks, crows, egrets, herons, and falcons, as well as some mammalian species. Q: How long is the virus viable outside of the host in the environment - i.e., how long does it remain contagious to birds or humans? A: HPAI viruses can remain viable for long periods of time at moderate temperatures in the environment, and can survive indefinitely in frozen material. In poultry houses, live virus has been found more than 100 days after the facility was depopulated. One gram of contaminated manure can contain enough virus to infect 1 million birds. Q: Most people who have become infected with H5N1 have been in quite close contact with ill birds, although there are a few troubling cases with unknown means of human exposure. How about a carcass - does the virus remain viable for very long after the bird has died? A: The HPAI virus is known to be viable in poultry carcasses; the duration of viability depends on the temperature of the carcass. HPAI can be isolated from both meat and bone marrow since it is a systemic illness in poultry. However, proper cooking of poultry easily kills the virus. To date, HPAI H5N1 is not present in US poultry or poultry products. Q: I assume droppings and other body fluids, and any vaporization or droplets of them, would be loaded with the virus just like the 'normal' human flu virus can be transmitted to others. Is this correct? A: Infected birds shed virus in saliva, nasal secretions, and feces. Susceptible birds can become infected when they have contact with contaminated nasal, respiratory, or fecal material from infected birds. Fecal-to-oral transmission is the most common mode of spread between birds. Birds that survive infection excrete virus for at least 10 days, both orally and in feces. HPAI viruses can also be spread by manure, equipment, vehicles, and people whose clothing or shoes have become contaminated with the virus. Q: Would one have to suit up in biohazard outfits to be protected or would more simple things like appropriate micron size mask, gloves, and GOOD hygiene work? A: To date, HPAI H5N1 has not been detected within the United States in either wild birds or domestic poultry. Please contact the USGS National Wildlife Health Center at 608-270-2400 to report observations of sick and dying waterfowl. For guidelines on how to safely handle sick or dead wildlife, visit www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_05_03.jsp The following recommendations were developed by the Department of Interior, US Geological Survey (USGS), in consultation with the Centers for Disease Control and Protection (CDC), and provide advice about practices and precautions people should exercise to reduce the risk of HPAI H5N1 viral infection based on the level of exposure to wild birds. It is important to check with your respective public health, animal health, and natural resource agencies for up-to-date information on HPAI H5N1. There is no known case where H5N1 has been directly transmitted from wild birds to humans. However, even apparently healthy wild birds can be infected with microorganisms other than HPAI, some of which are currently of more concern to human health in North America than HPAI H5N1, such as Chlamydiophila spp., Salmonella spp., and Campylobacter spp. Recommendations Thoroughly washing hands with soap and water (or with alcohol-based hand products if the hands are not visibly soiled) is a very effective method for inactivating influenza viruses, including HPAI. These viruses are also inactivated with many common disinfectants such as detergents, 10% dilution of household bleach, alcohol, and other commercial disinfectants. The virus is more difficult to inactivate in organic material such as feces or soil. The General Public should, as a general rule, observe wildlife, including wild birds, from a distance. This protects you from possible exposure to pathogens and minimizes disturbance to the animal. *Avoid touching wildlife with bare hands. If there is contact with wildlife, do not rub eyes, eat, drink, or smoke before washing hands with soap and water as described above. *Do not pick up diseased or dead wildlife. Contact your state, tribal, or federal natural resource agency if a sick or dead animal is found. Individuals handling sick or dead birds associated with a mortality event. *Follow the recommendations above and at a minimum wear protective clothing, including coveralls, rubber boots, and latex or rubber gloves that can be disposed of or disinfected. *Minimize exposure to mucosal membranes by wearing protective eyewear (goggles) and a particulate surgical mask (NIOSH N95 respirator/mask is preferable). *Decontaminate work area and properly dispose of potentially infectious material including carcasses. For additional Information see USGS Field Guide to Wildlife Diseases: www.nwhc.usgs.gov/publications/field_manual/chapter_4.pdf *Do not eat, drink, or smoke while handling animals. Recommendations if HPAI is detected in North America Individuals working with wild birds in areas where HPAI H5N1 has been detected, particularly during disease control operations, should consult with a health care provider and follow the latest guidelines from CDC and the World Health Organization for prophylactic medications and precautions for persons involved in avian influenza disease control: www.who.int/entity/csr/disease/avian_influenza/guidelines/Avian%20Influenza.pdf www.cdc.gov/flu/avian/professional/protect-guid.htm Q: Can/should educational and exhibit birds be vaccinated against AI? A: A USDA-approved vaccine for use in pet or wild birds to protect against HPAI H5N1 is not currently available. Conclusion Currently, the implications of HPAI H5N1 virus for North American wildlife remain unclear. If migratory birds carry and shed the virus along flyways, the potential exists for the virus to spread into additional migratory species and for the subsequent spread of HPAI H5N1 virus into other parts of the world including Europe, Australia, and North America. As noted, it is unclear whether infected birds are capable of migration, and carrying and shedding the virus. Bird migration is only one of the possible routes of introducing HPAI H5N1 to the North American continent. Travel by infected people, along with contaminated luggage or clothing, and transportation of infected poultry, including the smuggling of illegal pet birds, and other poultry equipment and products, are more direct means to transport the virus. According to the revised World Organization for Animal Health (OIE) International Terrestrial Animal Health Code, all H5 and H7 avian influenza viruses are regarded as "notifiable avian influenza" (NAI) when confirmed in domestic poultry. If H5 or H7 avian influenza is strongly suspected in a wild bird and/or confirmed by laboratory diagnostics, the State Veterinarian should be notified. A list of state veterinarians can be found at: www.aphis.usda.gov/vs/sregs/official.html Please contact the USGS National Wildlife Health Center at 608-270-2400 to report observations of sick and dying waterfowl. For guidelines on how to safely handle sick or dead wildlife, visit www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_05_03.jsp References Used Friend, M. 1999. Field Manual of Wildlife Diseases. General Field Procedures and Diseases of Birds. US Department of the Interior, US Geological Survey Information and Technology Report 1999-001: www.nwhc.usgs.gov/publications/field_manual/chapter_22.pdf Wildlife Health Bulletin #04-01: www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_04_01.jsp Wildlife Health Bulletin #05-02: www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_05_02.jsp Wildlife Health Bulletin #05-03: www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_05_03.jsp European Commission on Animal Health & Welfare: Avian Influenza: http://europa.eu.int/comm/food/animal/diseases/controlmeasures/avian/symptoms_en.htm US Dept of Agriculture, Animal & Plant Health Inspection Service (APHIS) Fact Sheet: Highly Pathogenic Avian Influenza: www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahavianflu.html CDC: Spread of Avian Influenza Among Birds: www.cdc.gov/flu/avian/gen-info/spread.htm Other references USGS National Wildlife Health Center: www.nwhc.usgs.gov/research/avian_influenza/avian_influenza.html Centers for Disease Control and Prevention: www.cdc.gov/flu/avian/index.htm The USDA website: www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?navid=AVIAN_INFLUENZA&navtype=SU Food and Agriculture Organization of the United Nations (FAO) Website: www.fao.org/ag/againfo/subjects/en/health/diseases-cards/special_avian.html (on the right, active link to AI and migratory birds) World Organization for Animal Health (OIE): www.oie.int/eng/info/en_avinf.htm CNN Health Library: Bird Flu: www.cnn.com/HEALTH/library/DS/00566.html Acknowledgements Thanks to Tracy S. DuVernoy, DVM, MPH, Dipl. ACVPM USDA, APHIS, VS Emergency Management, for confirming the validity of the information in this paper. To see the Avian Influenza Update (21 March 2006) click here. |
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