Avian influenza, or bird flu, is caused by avian influenza type A viruses that primarily infect birds but can sporadically infect humans. It poses significant economic risks to the poultry industry due to high mortality rates in infected flocks and associated production losses. Prevention involves biosecurity measures, vaccination, hygiene practices, and monitoring to mitigate transmission risks.

1. AVIAN
INFLENZA

2. WHAT IS AVIAN INFLUENZA?
Avian influenza or bird flu refers to the disease
caused by infection with avian (bird) influenza (flu)
Type A viruses. These viruses naturally spread among
wild aquatic birds worldwide and can infect domestic
poultry and other bird and animal species. Bird flu
viruses do not normally infect humans. However,
sporadic human infections with bird flu viruses have
occurred

3. Etiology
■ The etiology of avian influenza, commonly
known as bird flu, is primarily attributed to
influenza A viruses. These viruses belong to the
Orthomyxoviridae family and are characterized
by their ability to infect birds, particularly wild
birds like waterfowl and shorebirds.

4. Occurence And economic significance
■ Highly pathogenic avian influenza outbreaks can result in significant economic
losses for the poultry industry. Infected birds may die or require culling to prevent
the spread of the virus, leading to loss of production and revenue for poultry
producers. Additionally, trade restrictions may be imposed on affected regions,
further impacting the industry's profitability.
■ Infected birds may exhibit reduced egg production, poor growth rates, and
decreased feed conversion efficiency. This can prolong the time it takes to bring
birds to market weight, resulting in additional costs for producers.
■ Highly pathogenic avian influenza strains can cause high mortality rates in poultry
flocks, especially in chickens and turkeys. This not only leads to immediate losses
but also disrupts production schedules and increases the risk of secondary
infections among surviving birds.

5. TRANSMISSION
Avian influenza, or bird flu, can spread through various transmission routes,
primarily involving direct or indirect contact with infected birds or their secretions.
Here are the main modes of transmission:
■ Direct Contact: The primary mode of transmission is direct contact with infected
birds or their bodily fluids, such as respiratory secretions, saliva, feces, and blood.
Close contact between infected and susceptible birds facilitates the spread of the
virus within poultry flocks. This can occur through activities such as pecking,
mating, or sharing water and feed sources.
■ Indirect Contact: Avian influenza viruses can survive in the environment for varying
periods, depending on factors such as temperature and humidity. Indirect
transmission occurs when susceptible birds come into contact with contaminated
surfaces, equipment, or environments. This can include shared equipment,
vehicles, clothing, or surfaces contaminated with virus particles.

6. ■ Airborne Transmission: Avian influenza viruses can be shed through respiratory
secretions and dispersed into the air as droplets or aerosols. Airborne transmission
can occur over short distances within poultry houses or between neighboring farms,
especially in situations where ventilation systems are inadequate or when birds are
housed in close proximity.
■ Wild Bird Migration: Wild birds, particularly waterfowl such as ducks and geese, are
natural reservoirs for avian influenza viruses. Migratory birds can carry the virus
over long distances and introduce it to new areas, including commercial poultry
farms. Although direct transmission from wild birds to domestic poultry is less
common, it can occur when infected wild birds come into contact with domestic
birds or their environments.
■ Contaminated Feed and Water: Contaminated feed or water sources can serve as
vehicles for avian influenza virus transmission within poultry flocks. Virus particles
shed by infected birds can contaminate feed and water sources, leading to ingestion
by susceptible birds and subsequent infection.

7. ■ Human-to-Bird Transmission: While rare, avian influenza viruses have the
potential to infect humans who come into close contact with infected birds or
their environments. In some cases, humans may inadvertently introduce the
virus to poultry flocks through activities such as handling sick birds or
contaminated materials.

8. CLINICAL SIGNS
Avian influenza can present many signs in birds, from minor disease (with little or no
clinical signs) to disease that can quickly become fatal and lead to a serious epidemic.
Highly pathogenic avian influenza (A virus belonging to H5, H7, and H9 subtypes) is
characterized by serious signs and a fast deterioration towards death. The death rate
can then reach 100% in less than 2 days. Strains that are highly pathogenic can lead
to serious respiratory disease on humans. Some signs or symptoms are the following:
1. Respiratory Signs:
■ Difficulty breathing or labored breathing
■ Coughing or sneezing
■ Nasal discharge or mucus around the beak
■ Wheezing or rattling sounds while breathing

9. 2. Digestive Signs:
■ Decreased appetite or refusal to eat
■ Diarrhea (may be watery or bloody)
■ Vomiting or regurgitation
■ Swollen or discolored wattles or comb in chickens
3. Neurological Signs:
■ Head tilt or twisting of the neck
■ Incoordination or inability to walk properly (ataxia)
■ Tremors or seizures
■ Paralysis of wings or legs

10. 4. Decreased Activity and Weakness:
■ Lethargy or decreased activity levels
■ Weakness or reluctance to move
■ Huddling or isolation from the flock
■ Drooping wings or tail
5. Decreased Egg Production:
■ Reduced egg production in laying hens
■ Abnormal or soft-shelled eggs
■ Changes in egg quality (e.g., misshapen eggs)
6. Sudden Deaths:
■ High mortality rates, especially in severe outbreaks of highly pathogenic avian influenza
(HPAI)
■ Birds found dead without prior signs of illness

11. DIAGNOSIS
LPAI must be differentiated from other respiratory diseases or causes of
decreased egg production, including the following:
■ Acute to subacute viral diseases such as infectious bronchitis, infectious
laryngotracheitis, low virulent Newcastle disease, and infections by other
paramyxoviruses
■ Bacterial diseases such as mycoplasmosis, infectious coryza,
ornithobacteriosis, turkey coryza, and the respiratory form of fowl cholera
■ Fungal diseases such as aspergillosis
HPAI must be differentiated from other causes of high mortality rates, such
as virulent Newcastle disease, the peracute septicemic form of fowl cholera,
heat exhaustion, and severe water deprivation.

12. Pathology
■ The pathology of avian influenza involves the influenza A virus
infecting the respiratory tract of birds, causing inflammation
and damage to the respiratory epithelium. This can lead to
symptoms such as coughing, sneezing, difficulty breathing,
and in severe cases, respiratory failure and death.
Additionally, some strains of avian influenza viruses can
spread to other organs, causing systemic infection and
potentially leading to organ failure.

13. TREATMENT OF AVIAN INFLUENZA
■ Antimicrobials against secondary pathogens
■ Supportive care
Treating LPAI-affected flocks with broad-spectrum antimicrobials to
control secondary pathogens and increasing house temperatures
may decrease morbidity and mortality rates. Treatment with
antiviral compounds is not approved or recommended.

14. PREVENTION
Preventing avian influenza (bird flu) involves a combination of biosecurity
measures, vaccination (where applicable), surveillance, and public health
interventions. Here's a comprehensive overview of prevention strategies:
■ Implement strict biosecurity protocols on poultry farms to prevent the introduction
and spread of avian influenza. This includes controlling access to the farm,
restricting movement of personnel and vehicles, and using dedicated clothing and
footwear.
■ Maintain good hygiene practices, such as regular cleaning and disinfection of
equipment, vehicles, and facilities. Ensure proper disposal of poultry waste.
■ Separate poultry from wild birds and other animals that may carry the virus. Use
bird-proof enclosures and fencing to minimize contact.
■ Vaccination may be used as a preventive measure in areas where avian influenza
is endemic or where there is a high risk of introduction of the virus.

15. ■ Vaccination strategies may vary depending on factors such as the circulating
strains of avian influenza, the type of poultry production system, and local
regulations.
■ Implement surveillance programs to monitor for the presence of avian
influenza viruses in domestic and wild bird populations.
■ Coordinate with public health authorities to monitor for human cases of avian
influenza and implement appropriate measures to prevent transmission to
humans.
■ Encourage proper cooking of poultry products to ensure that any potential
virus present in meat and eggs is destroyed.

16. THANK YOU!