A new strain of highly pathogenic avian influenza (HPAI) is threatening poultry in the United States, both in backyards and in commercial facilities. A backyard flock in Michigan was diagnosed with the virus on February 24, 2022. Home to Roost recently talked with Dr. Anne Staudenmaier, VMD, DABVP (Avian Practice) of Ness Exotics in Lisle, IL, and Dr. Geoffrey Lossie (DVM, MS, DACPV), poultry diagnostician at Purdue University. Both vets provided us some information about the following questions related to avian flu.
Is avian influenza communicable to humans?
Dr. Staudenmaier provided us with a bit of background for this answer: There are many different strains of influenza, and they’re named based on two proteins that lie on the outer shell of the virus: H (for hemagglutinin) and N (for neuraminidase). Viruses are also divided into types A, B, and C. Type A viruses, which include all avian influenza viruses, are able to infect many different types of mammals, including humans, and because of this, are generally the ones responsible for epidemics. Types B and C are less diverse and have more limited host ranges. That being said, not every avian influenza strain is able to infect humans.
There are several subtypes that cause HPAI, including H5N1, H5N7, and H7N9; and several of these HPAI subtypes can affect humans. According to Centers for Disease Control and Prevention (CDC), the recent HPAI detected in wild birds and domestic flocks does NOT present an immediate public health concern, and human infections with H5 bird flu viruses are rare. In fact, no cases of human infection with highly pathogenic avian influenza A viruses have been detected to date in the United States. However, there are some cases of human infection with low-pathogenic influenza A viruses.
(Our big take-away was that viruses and their naming conventions are complicated. If we’ve gotten something wrong, please let us know!)
Home to Roost note: You can kill viruses and bacteria in poultry and eggs by cooking them to an internal temperature of 165°F. Also, experts say that animal-to-human transmission is unlikely.
How can backyard chicken keepers protect their flocks?
Wild birds are responsible for most cases of transmission to backyard flocks. Shore birds and waterfowl are considered to be natural hosts for influenza viruses and often spread disease during migration paths. Recent reports show bats carrying several new avian influenza strains. To protect your flock, Dr. Lossie points to the importance of biosecurity, especially now:
- Limit the amount of contact that wild birds have with your birds, including access to food and housing.
- Avoid hunting waterfowl because hunters can bring the virus back to their flocks.
- Limit all unnecessary visitors, especially those who have their own poultry.
- Do not interact with other keepers’ birds.
- Do not share poultry equipment (feed/water dishes, cages, incubators, etc.) with other keepers.
Dr. Lossie suggests reading the information here.
Should a case of avian flu be reported to the USDA or state department of agriculture?
This strain of virus is a highly pathogenic avian influenza (HPAI). Highly pathogenic means that this strain will cause more than 75% mortality (it can kill more than ¾ of your flock). If you suspect your flock has this virus, you must report it to the state. According to APHIS (Animal and Plant Health Inspection Service), all bird owners should report sick birds or unusual bird deaths to state/federal officials, either through their state animal health official, the state veterinary regulatory board, or through USDA’s toll-free number at 1-866-536-7593.
There are other reportable strains of low-pathogenic avian influenza (H5 and H7). The disease should be reported because it can cause devastation to commercial poultry flocks and the poultry industry. It is not due to the fear of a human outbreak, as many think; however, that does not mean there is no risk to humans.
A disease that kills even small percentages of commercial flocks can have serious impacts on food production and the economy. For more information on the impact of a devastating epidemic on livestock and the economy, read about the foot-and-mouth outbreak of 2001 in the United Kingdom.
The USDA is very thorough in monitoring the health of wild bird populations and commercial flocks.
What to watch for in your birds?
Dr. Staudenmaier states that the clinical signs can vary depending on the strain and can be nonspecific, or assignable to a number of conditions. Many of the following signs can be seen with other diseases, but there is always concern when multiple birds in a flock show signs, as opposed to just one bird. These signs include:
- Decreased egg production or abnormal eggs
- Swelling of the head/comb/wattles/eyelids
- Purple discoloration of the wattles/comb/legs
- Nasal discharge, coughing, sneezing
- Diarrhea
- Lack of coordination
- Decreased appetite
- Sudden death
Dr. Lossie points out that many birds dying in a short period of time can be suggestive of HPAI. The birds may not show signs initially, but after isolating themselves, they may stop eating and drinking and eventually die.
How to diagnose and treat HPAI?
Dr. Lossie stresses that avian influenza can only be tested for by a licensed state veterinary authority. Because avian influenza is considered a foreign animal disease, a state veterinary authority or the USDA, rather than a private veterinarian) should examine the bird(s). Dr. Staudenmaier states that to diagnose HPAI, the vet needs to run a polymerase chain reaction (PCR) test. This is the same type of test used to detect COVID-19. It searches for the RNA of the virus in samples from the mouth, cloaca, feces, or tissues. Serology, or blood tests, are also used to look for antibodies to the virus. These tests can detect HPAI in poultry but not in other avian species.
Regarding treatment, different recommendations may be made depending on the strain. For low pathogenic avian influenza, as long as it is not an H5 or H7 strain, treatment is supportive and focused on preventing secondary bacterial infections and supporting the immune system with fluids, anti-inflammatories, and vitamins. For HPAI (H5, and H7 strains), always follow the recommendations of your avian vet and your state and comply with all guidelines to ensure the health of the poultry industry. Dr. Lossie cautions that a flock that contracts avian influenza may need to be depopulated to protect others’ flocks and the commercial poultry industry.
Other helpful info for backyard chicken keepers
Dr. Staudenmaier offers these take-aways for backyard flock owners are the following:
- Prevent access of wild animals to your birds’ food and water sources. Wild birds and to a lesser extent, wild mammals, can transmit many different diseases to birds. One of the biggest ways to reduce risk is to store food in protected containers. Change food and water daily to reduce the possibility of attracting pests.
- Contact the USDA APHIS (Animal and Plant Health Inspection Service) and state veterinarian if you have question or concerns. They may be able to help with disease testing at discounted rates if you are worried about a disease like avian influenza.
Note: We thank editor and veterinarian Debra Teachout for her assistance with the science aspects of this article.
*Posted updated March 1, 2022, 3:27 PM.
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