News of avian influenza (bird flu) is resurfacing around the globe. Cases of H7N3 are confirmed in the U.S.; H5N8 has been reported in Poland, Hungary, Bulgaria, Czech Republic, Ukraine and Germany while H5N6 and H5N1 have been detected in Vietnam and the Philippines. These countries have culled thousands of birds so far this year to prevent the bird flu virus spreading. In this article, you will learn more about the signs and symptoms of avian influenza, how to prevent it in poultry and treatments for avian influenza in birds.
Signs and symptoms of avian influenza in poultry
Avian influenza is a disease caused by influenza type A viruses, which can infect both wild and domestic birds.
There are two clinical types of influenza virus in poultry: Highly pathogenic (HP) and low pathogenic (LP). The HP strains of bird flu can spread rapidly among poultry flocks and may cause multi-organ failure and sudden, high mortality. The LP strains of bird flu form as asymptomatic infections, respiratory disease or drops in egg production.
Symptoms indicating the presence of avian flu in poultry are:
- Sudden death without any signs
- Purple discoloration of the wattles, combs and legs
- Swollen head, eyelids, comb, wattles and hocks
- Soft-shelled or misshapen eggs
- Decreased egg production
- Lack of energy, appetite and coordination
- Nasal discharge
- Coughing or sneezing
- Ruffled feathers
How to prevent avian influenza in poultry
Avian influenza viruses spread through direct contact with infected birds or through contaminated feed, water, equipment and clothing. Therefore, biosecurity is the first and most important means of prevention at farm level.
For poultry producers to prevent the introduction of the virus in their ﬂock, they are advised to:
1. Reduce wildlife attractants:
- Remove standing water: Grade property to avoid pooling of water; avoid walking or moving equipment near standing water used by wildlife.
- Reduce food sources: Do not feed wildlife; locate feed structure on a clean pad; have quick clean-ups for the feed storage area; mow frequently and remove fallen fruits.
- Cover waste: Do not pile used litter near barns; close dumpsters properly; keep carcasses covered.
2. Prevent wildlife access: Install exclusionary netting, screens and perch deterrents, like repellent gel or bird spikes.
3. Add wildlife deterrents: Move and replace scare devices frequently.
4. Keep poultry away from areas frequented by wildfowl: Keep your birds indoors at high-risk times. If they cannot go indoors, make sure wild birds cannot access their feed and water sources.
5. Cover your run: Protect housed birds that may be able to have contact with wild birds, such as smallholding flocks in outdoor runs.
6. Keep control over the access of people and equipment to poultry houses: If infected wild birds are in the area, reduce the movement of people, vehicles or equipment to and from areas where poultry are kept. Change your clothes before and after contact with your flock, and ensure visitors do the same.
7. Maintain sanitation of property, poultry houses, equipment, vehicles and footwear: Disinfect regularly. For commercial poultry owners, clean and disinfect housing at the end of a production cycle. Wash your hands before and after contact with birds.
8. Avoid the introduction of birds of unknown disease status into the ﬂock: Acquire birds only from sources that can verify that they are disease-free. Then quarantine new birds for two weeks in separate quarters, to assure that they are healthy.
9. Report illness and death of birds: Contact a vet if you have any concerns. Quick actions will help to protect other flocks in the area if the disease is confirmed.
10. Appropriately dispose of manure and dead poultry.
11. Maintain surveillance: Follow local regulations regarding breeder flock monitoring and testing protocols as a minimum guideline.
Treatments for avian influenza in poultry
Treatment with antiviral compounds is not approved or recommended. It is best to have a monitoring system in place and biosecurity measures as prevention.
In case the disease is detected, a culling policy is commonly used to contain and eradicate the disease. When formulating a culling policy, the World Organization for Animal Health (OIE) recommends:
- Humane destruction of all infected and exposed animals.
- Appropriate disposal of carcasses and all animal products.
- Surveillance and tracing of potentially infected or exposed poultry.
- Strict quarantine and controls on the movement of poultry and any at-risk vehicles.
- Thorough decontamination of infected premises.
- A period of at least 21 days before restocking.
Vaccination can be a powerful tool to support eradication programs if used in conjunction with other control methods. Using emergency vaccination to reduce the transmission rate could provide an alternative to preemptive culling, reducing the susceptibility of healthy flocks at risk.
Did you know?
- You should handle raw poultry hygienically and cook all poultry and poultry products (including eggs) thoroughly before eating.
- Although avian influenza A viruses usually do not infect people, rare cases of human infection with these viruses have been reported after unprotected contact with infected birds or surfaces contaminated with avian influenza viruses (CDC, 2017).
- H5N1 is a highly pathogenic avian influenza (HPAI) virus. It is deadly for poultry and humans. The first human case occurred in 1997. Since November 2003, H5N1 has killed over 50% of the people who have been infected (WHO, 2020).
- H1N1 is a swine flu. Although it is also deadly, it is entirely different from H5N1, a bird flu.
- H7N9 bird flu is rated by the Influenza Risk Assessment Tool as having the greatest potential to cause a pandemic, as well as potentially posing the most significant risk to severely impact public health if it were to achieve sustained human-to-human transmission.
- Humans are usually infected through close contact with infected birds. Birds shed influenza virus in their feces. Therefore, contact with bird droppings is also a possible transmission route.
World Health Organization (2020), Cumulative number of confirmed human cases for avian influenza A(H5N1) reported to WHO, 2003-2020, 28 February 2020 table
Centers for Disease Control and Prevention (2017), Avian Influenza A Virus Infections in Humans