Avian Influenza: Veterinarians

FAQs of special interest to veterinarians

April 27, 2015

 

Avian influenza A H5N1 viruses
Colorized transmission electron micrograph of Avian influenza A H5N1 viruses (seen in gold) grown in MDCK cells (seen in green). Photo Credit: CDC/Cynthia Goldsmith

Q: Which subtypes have been identified in the USA?

A: There have been three subtypes identified in various locations across the U.S.:

  • H5N2 in commercial turkey flocks, layer flocks and backyard poultry in several states; and in wild fowl along the Pacific, Central, and Mississippi flyways. 
  • H5N8 in wild fowl along the Pacific flyway, as well as backyard poultry in Oregon, and commercial turkeys in California.
  • A new H5N1 in wild fowl along the Pacific flyway. This H5N1 strain differs substantially from the Asian origin strain that has circulated in Asia, Africa, and Europe. This is a mix of North American and Asian genes.

See USDA’s Avian Influenza Fact Sheet and list of National Veterinary Services Laboratory-confirmed HPAI findings in the U.S. for additional information.

Of note, H7N9 which has been circulating in East Asia, affecting people, has not been identified in the USA.

Q: What is HPAI?

A: Avian influenza (AI) is broadly divided into highly pathogenic (HPAI) and low pathogenic (LPAI) strains based on its ability to cause disease in poultry. Low pathogenic avian influenza is a natural infection of waterfowl that may cause minimal to no signs of disease in domestic poultry and wild birds. Highly pathogenic avian influenza rarely causes disease in waterfowl but these birds can transmit it to domestic poultry where it can cause a severe disease with  high case mortality (death).  Two types of avian influenza viruses, H5 and H7, are the most common highly pathogenic viruses found in nature. The H5 and H7 avian influenza strains are classified as “Highly Pathogenic Avian Influenza” (HPAI) by the World Organization for Animal Health (OIE) because, to date, HPAI viruses found have always been H5 or H7. It is important to understand, however, that not all H5 and H7 influenza viruses are highly pathogenic. Likewise, other strains that are not H5 or H7 can be considered highly pathogenic in certain circumstances. The USDA provides additional information in its Questions and Answers: Biology of Avian Influenza and Recent Outbreaks.

Q: How can companion birds become infected? Can they spread the virus?

A: Even though HPAI has been detected in the United States, indoor birds continue to have a very low risk of becoming infected. Birds housed outdoors, however, should be protected from contact with wild migratory birds (especially waterfowl and shorebirds), their droppings, and water frequented by waterfowl and shorebirds. If infected, it may be possible for companion birds to spread the virus.

Q: How can owners protect their bird(s)?

A: Biosecurity is the first line of defense against transmission of avian influenza to birds, including companion birds and commercial and backyard poultry.

The USDA recommends six steps to help keep birds safe:

Step 1: keep your distance. (See related USDA blog related to biosecurity.)
Step 2: keep it clean.
Step 3: don't haul disease home.
Step 4: don't borrow from your neighbor.
Step 5: know the signs.
Step 6: report sick birds.

Bird owners should prevent contact between their birds and wild birds, live bird markets, and any source of water that may have been contaminated by wild birds. Consideration should be given to moving flocks and individual birds housed outdoors to indoor accommodations if exposure to wild birds and their droppings is likely. Since influenza can be spread through fomites, bird owners should also take care not to expose their birds to shoes or clothing that may have been exposed to wild bird droppings, feathers, or water where wild water fowl congregate.

Access to poultry farms should be restricted to essential workers and vehicles, and all equipment and vehicles that enter and leave the farm should be thoroughly cleaned and disinfected. In addition, equipment, personnel, and vehicles should not be loaned to (or borrowed from) other farms. Birds obtained from live bird markets or via slaughter channels should not be brought back to the farm. View the USDA’s Questions and Answers on Protecting Birds from Avian Influenza in the United States for additional information on biosecurity for additional information on biosecurity.

Protecting domestic waterfowl from infection is problematic, because such birds are the natural hosts of all known AI viruses. The only practical measure to limit exposure to pathogenic strains of AI virus is to exclude wild or feral waterfowl from ponds and sources of water supplying the pond. Waterfowl may need to be brought indoors for short periods during an outbreak of avian influenza.

Q: What are the recommended control measures for free-roaming flocks?

A: Be prepared to confine birds indoors or in sheltered enclosures in the event that a highly pathogenic avian influenza virus is identified in your area. Ideally, free-roaming poultry should be completely sheltered so exposure to wild birds and their droppings and other environmental contamination is minimized.

Q: Do owners need to move birds inside when highly pathogenic avian influenza virus is detected in the area?

A: It depends on how likely it is that the birds will be exposed to wild birds and/or their droppings if they remain in their current housing system. There is a low risk of transmission to companion birds unless they mingle with wild migratory waterfowl or are exposed to their droppings. If highly pathogenic avian influenza is identified in an area close to an owner's flock, state animal health authorities may require that owners move their birds indoors as a preventive measure. Biosecurity practices should be strictly followed.

Q: What can exotic waterfowl breeders/fanciers do to protect their birds?

A:  Exotic waterfowl breeders and fanciers should exclude wild and feral waterfowl from their ponds and, if possible, the water source feeding those ponds. If an outbreak of highly pathogenic avian influenza occurs in close proximity to kept birds, those waterfowl should be penned indoors or in sheltered enclosures until the danger has passed.

Q: Is there a vaccine available to protect companion animals against highly pathogenic avian influenzavirus? 

A:  Currently, although there are USDA-licensed vaccines to protect against highly pathogenic avian influenza available, they can only be used when approval is given by federal and state animal health authorities, no matter the animal species. Avian influenza vaccines against highly pathogenic avian influenza may be used only within an official USDA control program, according to National Animal Health Emergency Management System/Foreign Animal Disease Preparedness & Response Plan (NAHEMS FAD PReP) Guidelines Appendix C.

Q: What types of testing are available for detecting highly pathogenic avian influenza virus infection, and how reliable are they?

A: A variety of tests are available and validated for poultry species, including virus isolation (VI),  real-time reverse transcriptase polymerase chain reaction (rRT-PCR), and antigen capture immuno-assay. The rRT-PCR is performed by all National Animal Health Laboratory Network (NAHLN) laboratories and other veterinary laboratories approved by USDA National Veterinary Services Laboratories (NVSL) for this purpose. Many NAHLN laboratories perform VI as well. A substantial drawback to VI is the delay in obtaining the results and the requirement for strict biocontainment during harvest of samples.

Both VI and rRT-PCR can be applied, with caution, to non-poultry species. The rRT-PCR testing performed by NAHLN laboratories is specific for all influenza A viruses, and then further testing is performed for important subtypes. This test would be expected to detect infection in any species that is actively shedding virus. Test results can be available in as little as a half day (12 hours), and USDA has indicated that the results of rapid screening can be expected within 4 to 7 hours after receipt by the NVSL. There are also commercially available tests, many of which identify viral proteins.

Serologic (blood serum) testing using agar gel immunodiffusion (AGID) can be used in a variety of avian species and can be used to demonstrate an animal or flock’s freedom from infection. For suspected cases, necropsy is best performed at a NAHLN facility. Veterinarians should contact the laboratory before submitting birds for necropsy. View a directory of NAHLN laboratories and a Fact Sheet from USDA related to diagnostic tests in the United States.

Q: If infection with highly pathogenic  avian influenza virus is suspected, what diagnostic samples should be obtained, how should they be shipped, and where should they be shipped?

A: If you suspect a pet bird or backyard flock is infected with avian influenza, you should immediately contact the state animal health official. Avian influenza is considered a reportable disease by the World Organization for Animal Health (OIE) and required to be reported to USDA and state authorities. Depending on the situation, the official might identify a regulatory official or other authority to present to the location for samples. If you are directed to take samples, recognize that appropriate precautions (i.e., use of personal protective equipment) should be taken when obtaining samples from birds. Contact the NAHLN laboratory for specific, up-to-date information on the appropriate collection and submission of samples and carcasses. View AVMA’s webpage describing training and other requirements for shipping biological specimens. Also see the USDA FAD PReP HPAI Response Plan.

Q: Does testing for highly pathogenic avian influenza virus infection require euthanasia?

A: Not always, however, depending on the species of bird and situation, a necropsy may be warranted to determine whether a bird or flock of birds is infected with highly pathogenic avian influenza. Such a decision is best made following consultation with the state animal health official.

In the absence of formal protocols developed and recommended by such regulatory agencies, if an animal is suspected to be infected with avian influenza, it may be appropriate to submit samples to at least one of the diagnostic laboratories in the National Animal Health Laboratory Network (NAHLN) for preliminary diagnosis before recommending euthanasia, particularly for companion animals. View a directory of NAHLN laboratories.

Q: If results of a test are positive, what will be done with the affected companion animal and what about What about other pets in the household, including companion birds?

A: Unfortunately, risks associated with transmission of avian influenza from pet birds and backyard flocks to other animals and people in the household have not been well documented, and making specific recommendations for management of potentially affected animals is difficult. Because avian influenza is a reportable disease, the state animal health official will advise you on specific steps. In addition to any specific instructions from the state animal health official, the National Association of State Public Health Veterinarians has a helpful Compendium on Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel which can be consulted.  In general, pets should be quarantined and the premises disinfected if highly pathogenic avian influenza (HPAI) is suspected. In the absence of other recommendations, treatment of affected companion animals is symptomatic.

According to findings during past HPAI enzootics, both cats and dogs should be monitored for clinical signs, as illnesses in companion animals could indicate there are changes in the virus affecting the pet bird or backyard flock. A 2012 article by the CDC suggests that cats are at risk of disease and/or death from some strains of HPAI. However, the risk with the current strains is unknown. If a pet bird or backyard flock had a positive test result, seek advice from the state animal health official regarding the bird or flock’s disposition.

Additionally, because companion animals may play a role in the evolution of some influenza viruses, it behooves veterinarians to stay vigilant of pets within a household whose pet birds have been diagnosed with HPAI. Other companion animals, such as ferrets, might also be at risk.

In addition to any specific instructions regarding personal protective equipment (PPE) and biocontainment by the state animal health official, the National Association of State Public Health Veterinarians has a helpful Compendium on Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel which can be consulted.

Q: What are the risks to humans and other animals while awaiting test results, and what precautions should be taken?

A: Risks to humans and other animals exposed to infected animals vary considerably by species and situation; in general, closer, more prolonged contact equates to increased risk.

While awaiting test results, animals suspected to be infected should be quarantined, and family members, pets, and other animals that may have been exposed should be monitored for signs of illness. Animal owners and veterinary staff should be made aware of risks to themselves and other individuals with whom the animal may have come in contact.

The advice of local, state, and federal public health authorities should be sought in the management of suspected cases, and these officials must be notified of confirmed cases. View contact information for the USDA-APHIS Veterinary Services Area Office in your state. View a listing of public health veterinarians by state.

Q: If highly pathogenic avian influenza virus infection is suspected in a companion animal, when should I report it, and to whom?

A: If any type of poultry is suspected to be infected (backyard flocks, live bird markets, show chickens), the State Department of Agriculture or the USDA (1-866-536-7593) should be notified immediately, per the Code of Federal Regulations (9CFR161.3). If the affected animal is a companion animal (e.g., cat, dog, ferret, pet bird), depending on your state regulations, either the state animal health official or the state public health veterinarian should be notified. View contact information for the USDA-APHIS District Office in your state.

Q: Can/Should I treat highly pathogenic avian influenza virus infection in my patients?

A: If an animal is exhibiting clinical signs that may indicate infection with a highly pathogenic avian influenza (HPAI) virus, treatment should not be initiated without first notifying appropriate federal and state authorities. If a commercial poultry flock is affected, the premises and bird(s) should be immediately quarantined, and exposure to birds should be limited, until regulatory officials can respond or direct the veterinarian regarding an appropriate course of action. Currently, infected poultry are euthanized and poultry products are destroyed when HPAI infection is confirmed (recovery from HPAI infection is extremely rare). The outcome may also be influenced by the producer’s participation in secure food supply plans.

If authorized to treat, recall the FDA’s rule prohibiting the extralabel use of adamantine and neuraminidase inhibitor classes of antiviral drugs in chickens, turkeys, and ducks.

Because other diseases may cause similar clinical signs, treatment of affected cats or dogs should begin pending confirmation of infection. Specific antiviral agents are not available for cats or dogs infected with HPAI, and drugs used to treat humans with influenza (e.g., neuraminidase inhibitors such as zanavimir or oseltamivir) have not been adequately explored in these species. Recommended treatment is, therefore, supportive. How cats and dogs naturally infected with HPAI will respond to treatment is not known. The extent of risk to veterinarians and clinic personnel posed by animals that receive medical care and survive is also not known. View National Animal Health Emergency Management System Guidance on personal protective equipment related to zoonotic diseases, and the veterinary infection control guidelines issued by the National Association of State Public Health Veterinarians.

Q: How can I differentiate highly pathogenic  avian influenza virus infection from kennel cough or canine influenza?

A: HPAI infections in dogs have been reported to occur occasionally, with signs including fever, panting, and lethargy in one international case report. Signs reported in another experiment include conjunctivitis, dyspnea, and anorexia. However, the susceptibility to the current strains of HPAI in the U.S. is unknown.

Given detection of novel influenza subtypes in the USA, it should be considered on the list of differential diagnoses for dogs exhibiting respiratory signs that have a history of exposure to avian influenza such as known exposure to HPAI infected birds should be taken into consideration. Lacking a more complete description of typical clinical signs, differentiation from kennel cough or canine influenza would be difficult without laboratory confirmation.

Q: How can I differentiate highly pathogenic avian influenza virus infection from feline upper respiratory tract infection?

A: Clinical signs in infected cats have not been extensively described, but include fever, listlessness, conjunctivitis, difficulty breathing, and death. These signs are commonly encountered in other respiratory disease syndromes of cats, so laboratory confirmation of highly pathogenic avian influenza virus infection is necessary for a definitive diagnosis.

Q: If a bird is suspected or confirmed to have highly pathogenic  avian influenza virus infection, is the staff that handled the bird at risk?

A: Potentially, depending on the extent of contact. Appropriate personal protective equipment should be worn when examining animals suspected to have highly pathogenic avian influenza (HPAI). Local, state, and federal public health authorities should be notified if avian influenza infection is suspected. The H5N2 HPAI strain in North American has not infected humans to date.

See the NAHEMS Guidance on personal protective equipment for more information.

Q: If a companion animal is suspected to have highly pathogenic avian influenza virus infection, how should the premises be disinfected?

A: The highly pathogenic avian influenza (HPAI) virus can be easily inactivated with various EPA-approved disinfectants. The USDA District Office, the state animal health official, and state public health veterinarian should be contacted for specific instructions on the most appropriate approach to disinfection.

The Environmental Protection Agency (EPA) registers pesticides, including disinfectants, for decontamination and control of pathogens on environmental surfaces of livestock and food-related facilities and equipment. Approximately 100 disinfectant products are registered and intended for use against influenza A viruses on hard, nonporous surfaces, including poultry houses, farm equipment, veterinary premises, and industrial settings. A list of suitable products is on the EPA Web site. These products are typically used by the poultry industry to disinfect their facilities.

Q: How do I safely dispose of dead birds?

A: In the case of wild birds, USDA-APHIS Wildlife Services personnel are available to determine whether the carcasses are appropriate for avian influenza testing (or for another potentially infectious disease). Carcasses should not be disturbed prior to that decision being made. Contact USDA Wildlife Services at  1-866-4-USDA-WS or the state department of wildlife (see Association of Fish and Wildlife Agencies for listing of state authorities).If a companion bird has died, and if the practitioner suspects HPAI as the cause, the state animal health official or the USDA District Office should be contacted for advice regarding samples for testing and disposal of the carcass.

If it is determined that it is appropriate to dispose of a dead bird, the CDC National Institute for Occupational Safety and Health recommends in a 2008 Alert that workers potentially exposed to avian influenza use a respirator (N95 or above), gloves, outerwear, head protection, goggles, and foot protection . Additionally, the USDA’s National Veterinary Accreditation Program’s PPE for Veterinarians Module provides general guidance. The bird can then be disposed of as recommended by the USDA, state animal health official, or state public health veterinarian.

Q: Where do I look for additional information and resources?

A: Links to Information about Avian Influenza

American Veterinary Medical Association Avian Influenza Frequently Asked Questions

American Association of Avian Pathologists: Avian Influenza Position Statement
Association of Avian Veterinarians (AAV)
National Association of State Public Health Veterinarians (NASPHV)
National Poultry Improvement Plan 
Pork Checkoff Influenza Materials for Clients
USDA Highly Pathogenic Avian Influenza Diagnostic Training Course
University of California-Davis Avian Flu School: International Course Guide

University of Minnesota Avian Influenza: The Basics

International e-Learning Course on Avian Influenza

Department of Health and Human Services Information on Pandemic Flu and Avian Influenza
Centers for Disease Control and Prevention (CDC) Avian Influenza (Bird Flu)
Avian Influenza: Advice for Travelers
USDA Avian Influenza (Bird Flu)
USDA Biosecurity for the Birds
USDA-APHIS District  Offices (listing by state)
Designated State Animal Health Officials (listing by state)
Designated State Public Health Veterinarians (listing by state)
USDA-APHIS Wildlife Services (listing by state)
Secure Food Supply
AVMA Animal Carcass Disposal (member login required)
Protecting Poultry Workers from Avian Influenza
EPA: Registered Antimicrobial Products with Label Claims for Avian (Bird) Flu
US Poultry & Egg Association
World Health Organization (WHO) Avian Influenza Resource
Food and Agriculture Organization (FAO) of the United Nations (Avian Influenza)
North American Plan for Animal and Pandemic Influenza