What is Avian Influenza in Poultry (AI) or Bird Flu?
Avian Influenza, commonly known as bird flu, is a viral disease caused by a virus from the Orthomyxoviridae family that primarily affects poultry. The severity of the disease in infected birds varies significantly depending on the viral subtype. Low Pathogenicity Avian Influenza (LPAI) viruses often cause mild symptoms or no clinical signs at all. In contrast, High Pathogenicity Avian Influenza (HPAI) viruses lead to severe symptoms, rapid spread, and high mortality rates in chickens and other poultry.
This highly contagious viral disease can affect all birds, both domestic and wild, especially waterfowl. It can infect poultry species such as chickens, turkeys, pheasants, quails, ducks, and geese. While most viral subtypes are not zoonotic, meaning they are not transmissible between animals and humans, some HPAI subtypes do have the ability to infect humans and are considered a threat to public health. The virus rapidly evolves and is divided into numerous subtypes (including H5N1, H5N3, H5N8, etc.), with different subtypes prevalent in various regions around the world.
Classification of Avian Influenza Subtypes
Avian Influenza viruses are categorized into two main groups based on their ability to cause disease, or pathogenicity:
Low Pathogenicity Avian Influenza (LPAI): These viruses have low pathogenicity and cause few or no clinical symptoms in infected poultry.
High Pathogenicity Avian Influenza (HPAI): This is a highly pathogenic type A virus, primarily from the H5 and H7 subtypes. These viruses not only cause severe clinical signs but also have a high mortality rate in poultry flocks.
Viruses are described by their primary antigenic determinants, Hemagglutinin (H) and Neuraminidase (N). The current highly pathogenic strain of concern is H5N1. It is well-established that LPAI H5 and H7 subtypes can mutate into a highly pathogenic form, which can cause significant mortality in poultry.
Avian Influenza Symptoms in Poultry
Early recognition of Avian Influenza symptoms is crucial for controlling a disease outbreak and saving your flock. The clinical signs of bird flu can vary; sometimes they are very subtle and hidden, while at other times, they are rapidly fatal. For this reason, if you observe any suspicious symptoms, you must immediately contact your veterinarian or local animal health authority. Early diagnosis and rapid reporting are the only ways to prevent widespread disease and reduce potential losses.
Below, we will review the Avian Influenza symptoms in chickens and poultry based on the type of bird so you can more accurately assess your flock’s condition.
Symptoms of Avian Influenza in Broiler and Native Chickens
In broiler and native chickens, the clinical signs of the disease are highly dependent on the type of virus:
- In Low Pathogenicity Avian Influenza (LPAI): Symptoms are typically minor and mild. You may observe lethargy, a slight reduction in appetite, or mild respiratory issues like sneezing and coughing. Diagnosing this type of bird flu is very difficult based on clinical signs alone.
- In Highly Pathogenicity Avian Influenza (HPAI): Symptoms are very sudden and severe. Many poultry farmers ask, “Is Avian Influenza deadly?” The answer is found in the symptoms of this disease. The first and most critical sign is the sudden and mass mortality of poultry, which can wipe out a large portion of the flock in a short period. In addition to severe lethargy and sickness, affected poultry show signs such as severe, watery diarrhea (which can be yellowish-green or even bloody), severe respiratory distress like gasping, and swelling around the head and eyes. For these reasons, the chickens will also suffer from weight loss, which will impact broiler performance. One of the distinguishing signs of this type of disease is cyanosis (bluish discoloration) of the comb and wattle. Sometimes the severe gastrointestinal symptoms of bird flu are so similar to other diseases, such as Necrotic Enteritis in poultry, that they can be mistaken. However, the key is that Avian Influenza is often accompanied by serious respiratory and nervous signs that are not seen in Necrotic Enteritis.
Avian Influenza Symptoms in Laying Hens
- In Low Pathogenicity Avian Influenza (LPAI): One of the most prominent symptoms in laying hens is a sudden drop in egg production (more than 5%). Additionally, the eggs may have thin shells or be misshapen.
- In Highly Pathogenicity Avian Influenza (HPAI): In this type, the drop in egg production is accompanied by a rapid onset of clinical signs and a very high mortality rate. Birds may appear depressed and have ruffled feathers before death.
Avian Influenza Symptoms in Turkeys and Other Poultry
In turkeys and other poultry such as pheasants and quails, in addition to respiratory and gastrointestinal symptoms, nervous signs are also common. These can include tremors, a twisted neck, wing paralysis, and a loss of balance.
Furthermore, wild waterfowl, like ducks and geese, may be infected with the Avian Influenza virus but rarely show clinical signs. This makes them dangerous carriers, capable of transmitting the disease to domestic poultry.
Transmission and Spread of Avian Influenza in Poultry
One of the most critical questions about this disease is: How is Avian Influenza transmitted? The Avian Influenza virus (AI) is highly contagious and spreads rapidly between birds through various factors, and in specific circumstances, to humans. Many factors play a role in the spread of this disease, including migratory wild birds, live bird markets, and international trade of poultry.
Direct Transmission
This is the most common route of infection. Healthy birds become infected through direct contact with sick birds, specifically through their nasal, oral, and ocular secretions.
Indirect Transmission
The Avian Influenza virus is highly resilient and can survive for long periods, especially in low temperatures. This makes indirect transmission one of the most dangerous routes for disease outbreaks across a region. The virus can be introduced to a flock through the following:
- Contaminated droppings: Poultry droppings are a primary source of the virus and can easily contaminate the water, feed, and environment of a farm.
- Contaminated tools and equipment: Farm tools and equipment, transport trucks, and even the clothes and shoes of workers can carry the virus from one poultry farm to another.
- Airborne transmission: Fine dust particles or respiratory droplets from infected birds can disperse in the air and lead to the transmission of the virus.
The Key Role of Wild Birds in Disease Spread
Migratory wild birds play a crucial role in the global spread of Avian Influenza, often moving the virus between countries and regions. These birds, especially waterfowl, typically do not show symptoms themselves but carry the virus in their bodies. They can then transmit it to domestic poultry by contaminating ponds and wetlands. According to data from the World Organization for Animal Health (WOAH), highly pathogenic Avian Influenza has its lowest prevalence in September, begins to increase in October, and peaks in February. This seasonal pattern is directly linked to the migration patterns of wild birds.
Ultimately, proper biosecurity management and preventing the entry of external factors are the main keys to preventing the spread of this disease in your flock.
Treatment of Avian Influenza in Poultry
One of the main concerns for poultry farmers is how to manage Avian Influenza on their farms. Unfortunately, it must be stated that there is no specific or definitive treatment for this disease. The Avian Influenza virus replicates rapidly after entering a bird’s body, and no specific medication exists to eliminate it. As a result, the primary focus is on disease management and control.
Official Control Measures
Unfortunately, if a poultry bird is infected with a highly pathogenic Avian Influenza strain, you will likely face high mortality due to the rapid progression of the disease. Within two or three days, severe symptoms and a high rate of spread will be observed in the flock. In such conditions, the following measures are essential for control:
- Rapid Diagnosis and Isolation: The first and most critical step is to immediately isolate any suspicious birds to prevent contact with healthy ones.
- Culling of Infected Flocks: Upon confirmation of a highly pathogenic (HPAI) strain, the entire flock is typically culled to prevent further spread of the disease.
Supportive Care for Poultry Against Avian Influenza
Despite the lack of a definitive treatment for Avian Influenza in broiler or other poultry, supportive measures can be used to reduce losses and improve the flock’s condition:
- Antibiotics: These medications do not eliminate the virus, but they are used to prevent secondary bacterial infections, as sick birds are weakened and more susceptible to other infections.
- Vitamins and Supplements: The use of multivitamins and electrolytes helps to strengthen a bird’s immune system and increases its ability to cope with the disease.
- Improved Housing Conditions: Proper ventilation, dry bedding, and healthy food help the birds tolerate the disease more easily.
Different Approaches for Broiler and Laying Hens
- Broiler Flu: The main goal is to reduce mortality and get the birds to market weight as quickly as possible. Broad-spectrum antibiotics are used to prevent secondary infections. It is crucial to adhere to the drug withdrawal period for broiler chickens to ensure contaminated meat does not enter the market.
- Laying Hens Flu: The main goal is to maintain the health of the flock and continue high-quality egg production. Milder antibiotics with shorter withdrawal periods are used, as some medications can transfer into the eggs. Additionally, the use of multivitamins and supplements is important to prevent a drop in egg production.
Are Home Remedies for Avian Influenza in Poultry Possible?
The answer to this question is a definitive no. Home remedies for Avian Influenza are not possible with traditional methods or ordinary medications. Antibiotics only reduce secondary infections and have no effect on the primary virus. Therefore, if you observe any suspicious symptoms, you must immediately contact a veterinarian.
Preventing Avian Influenza on Poultry Farms
Because there is no definitive treatment for Avian Influenza, prevention is the only effective way to protect your flock and avoid significant economic losses. The most important principle in preventing this disease is adhering strictly to biosecurity measures, which means preventing the virus from entering your farm.
Below are the most critical steps every poultry farmer should take to reduce the risk of disease.
Controlling Access for People and Vehicles
Limit entry: Only essential personnel should be allowed onto the poultry farm premises.
Use dedicated clothing and footwear: Individuals must wear clean, disinfected clothing and footwear before entering the poultry houses. Disinfection stations at entrances should be refilled daily.
Disinfect vehicles: All vehicles, especially poultry transport trucks, must be washed and disinfected before entering the farm.
Protecting the Environment and Your Flock
Keep out wild birds: Wild birds are the primary carriers of the Avian Influenza virus. Use nets, fences, and other barriers to prevent them from entering poultry houses.
Maintain hygiene and disinfection: Regular cleaning and disinfection of the environment and equipment are among the most essential preventive measures. Floors, walls, cages, and tools must be washed periodically with standard disinfectants.
Ensure proper ventilation: Proper ventilation of poultry houses is crucial. It helps reduce dust and airborne particles that could carry the virus. It also lowers stress in the birds and increases their resistance to disease.
Protect feed and water: Feed and water sources must be cleaned regularly and protected from contamination by wild bird droppings.
- Flock Management and Vaccination
- Manage flock hygiene: Maintaining clean litter and properly managing temperature and humidity helps to keep the flock healthy and increases its resistance to disease.
- Vaccination: A vaccine is a preventive tool that can reduce the severity of the disease and the mortality rate. However, it is not sufficient on its own and must be used as part of a comprehensive biosecurity program. The use of vaccines is subject to the veterinary policies of each country.
Ultimately, rapidly reporting suspicious cases to local veterinary authorities is the first and most critical step in containing the disease in its early stages and preventing a widespread outbreak.
Transmission of Avian Influenza to Humans
Avian Influenza, or bird flu, is primarily a disease of poultry, but under specific conditions, it can be transmitted to humans. When asked, “Does Avian Influenza spread to humans?”, the answer is that while the low-pathogenicity type is not transmissible, the highly pathogenic type (HPAI) can be. However, transmission is very rare and typically only occurs when an individual has direct and prolonged contact with infected birds or a heavily contaminated environment.
Primary Routes of Transmission to Humans
The virus is mainly transmitted to humans through direct or indirect contact with sick or dead birds. This poses a higher risk for people who work directly with diseased poultry, such as farmers or veterinarians. The virus can be transmitted to humans through the following ways:
- Direct contact with birds: Handling infected, sick, or dead birds, including chickens, roosters, ducks, turkeys, and ornamental birds.
- Contact with droppings and secretions: Contact with the feces, and nasal, oral, and eye secretions of infected birds, which contain a high concentration of the virus.
- Contaminated tools and environment: Touching contaminated items and surfaces, such as cages, feed and water containers, and the clothing of farm workers.
- Slaughtering and plucking: Slaughtering or preparing infected poultry for cooking without wearing protective masks, gloves, and clothing.
- Live bird markets: If traveling to countries where bird flu is prevalent, avoid visiting live bird markets.
Important Note: Avian Influenza is not transmitted through thoroughly cooked chicken or eggs, even in outbreak areas. The virus is eliminated by cooking.
Avian Influenza Symptoms in Humans
According to the WHO (World Health Organization), humans can become infected with Avian, swine, and other types of animal influenza viruses. Exposure to animal influenza viruses can lead to human infection and illness, ranging from mild symptoms like eye inflammation to severe acute respiratory illness or even death. The severity of the illness depends on the specific virus causing the infection and the characteristics of the infected person. Currently, zoonotic Avian Influenza viruses have not shown sustained human-to-human transmission. Since influenza viruses have a natural reservoir in wild waterfowl, their eradication is impossible.
The symptoms of Avian Influenza in humans are similar to those of human influenza. In general, bird flu symptoms appear very quickly and include the following:
- A very high temperature, or feeling hot or shivery (fever over 38°C / 100.4°F)
- Aches and pains in muscles
- Headache
- Cough or shortness of breath
- Sore throat
- Eye inflammation (conjunctivitis)
- Malaise and lethargy
- Lower respiratory tract involvement
- Respiratory distress
- Tachypnea (rapid breathing)
- Pneumonia
Note: Patients who develop pneumonia usually have a history of contact with infected or deceased birds. Pneumonia is an infection that inflames the air sacs in one or both lungs.
Other early symptoms of Avian Influenza may include:
- Diarrhea
- Nausea
- Abdominal pain
- Chest pain
- Nosebleeds and bleeding from the gums
The first symptoms usually appear 3 to 5 days after exposure. After a few days, the illness may cause severe complications such as pneumonia and acute respiratory distress syndrome (ARDS). Prompt medical attention and the use of antiviral drugs can help manage the disease and prevent it from worsening, as unfortunately, this illness can lead to death.
Based on the information above, if you experience symptoms, seek medical help immediately. Be sure to provide your doctor with complete information. The following details should be given to your treating physician for better diagnosis and treatment of Avian Influenza:
- If you have traveled to areas where bird flu viruses are present.
- If you have been within one meter of a sick or deceased bird.
- If you have had close contact with any person suffering from a severe respiratory illness.
- If you have had close contact with any person who died unexpectedly in an outbreak area or who had contact with individuals from that area.
Diagnosis of Avian Influenza
The following tests are performed for final confirmation of Avian Influenza:
- Sampling of nasal or throat mucus using a nasal swab.
- If the patient has a cough with phlegm, a sputum sample is used for testing.
If the test result is negative, it is highly unlikely that the patient has Avian Influenza.
Ways to Prevent the Transmission of Avian Influenza (Bird Flu) to Humans
Practicing good hygiene is crucial for preventing the transmission of Avian Influenza, especially during an outbreak. Generally, to prevent the spread of bird flu to humans, you should follow these guidelines:
Always wash your hands thoroughly with warm water and soap, especially before and after handling food, particularly poultry.
- Use separate utensils for raw and cooked meat.
- Make sure that all meat is cooked completely.
- Avoid direct contact with live poultry.
- Do not get close to or touch bird droppings, sick, or dead birds.
- Avoid visiting local live animal markets.
- Refrain from transporting birds during travel.
- Do not consume raw or undercooked chicken or duck.
- Do not eat raw eggs.
Note: There is no specific Avian Influenza vaccine for humans. Additionally, the seasonal flu vaccine does not protect a person against bird flu.
The Pan American Foot-and-Mouth Disease Center (PANAFTOSA) has also recommended that animal influenza response teams be trained and equipped with the necessary resources for emergency situations. Furthermore, it is critical for poultry producers to strengthen biosecurity on their farms. They should quarantine their birds or prevent any contact between their domestic flocks and wild birds.
At the same time, it is vital for farmers to quickly identify disease in their flocks and report it to a veterinarian. Necessary and appropriate measures should be taken until Avian Influenza is either confirmed or ruled out. Similarly, families who raise poultry like chickens and ducks for personal consumption should be aware of how to identify an infected bird, what actions to take, and how to protect themselves.
Treatment of Avian Influenza in Humans
If you suspect you may have been infected with Avian Influenza, it is best to stay home or be cared for in a hospital, isolated from other patients. To treat and manage the disease, a doctor will prescribe antiviral drugs. These medications help reduce the severity of the illness, prevent further complications, and improve the patient’s chances of survival. In some cases, these same drugs may also be prescribed to individuals who have been in contact with a patient (such as family and colleagues), healthcare workers, and people who have been in close contact with infected poultry.
The Global Impact of Avian Influenza
An outbreak of Avian Influenza can have severe consequences for the poultry industry, the health of wild birds, the livelihoods of farmers, and even international trade. Avian Influenza can wipe out an entire flock, causing significant damage to the agricultural sector. The key impacts of Avian Influenza include:
For Farmers: A poultry farmer may experience a mortality rate of over 50% in their flock.
Job Loss: Due to the losses on poultry farms, the workforce in the chicken industry may face unemployment. The economic effects are especially severe in developing countries.
Public Perception: Public confidence in purchasing products from affected areas may decline. Travel and tourism to these regions can also decrease.
Reduced Protein Supply: The outbreak of Avian Influenza and the resulting loss of birds can lead to a reduction in the global protein supply.
Additionally, international trade of live birds and poultry meat becomes restricted, which severely impacts the regional economy.
Impact on Animal Health and the Ecosystem
In severe outbreaks with high mortality rates, the virus heavily impacts the health of both poultry and wild birds. This is particularly critical for the conservation of endangered animals. Furthermore, the spread of Avian Influenza in wild birds has the potential for a devastating impact on ecosystem biodiversity.
Human Health Risk
Generally, individuals who have close and direct contact with birds, or who are in a highly contaminated environment, are at risk of contracting Avian Influenza.
What is the Role of Wild Birds in the Spread of Avian Influenza?
Migratory wild birds, especially waterfowl, are the primary hosts of the Avian Influenza virus. Depending on the viral type and the species of bird, the virus can be harmless or fatal. When birds are asymptomatic or show only minor clinical signs, they can easily spread the virus to neighboring countries and along their migration routes.
The main species in the transmission cycle of Avian Influenza are waterfowl, such as seagulls and shorebirds. At the same time, the virus can easily transmit between different species. For this reason, it is best to keep your domestic poultry in a quarantined area to prevent contact.
Is There a Concern That the Avian Influenza Virus is Spreading to Non-Avian Animals?
Yes, there is a concern, as cases of viruses like Type A(H5N1) have been reported in mammals, including both wild and domestic animals. The adaptation of the virus, particularly within mammals—which are biologically closer to humans—is worrying. For this reason, close regional, national, and global surveillance of circulating viruses is essential to identify any potential changes or adaptations that could make the virus transmissible to humans. This monitoring includes not only all Avian Influenza subtypes but also other zoonotic flus, such as swine flu.
Why is Animal Surveillance and Early Detection of Avian Influenza So Important?
Monitoring animals and birds helps us understand which influenza groups are circulating in a region. This allows us to quickly detect the presence of zoonotic viruses, which are known to constantly change and become more adaptable, increasing their transmissibility. All of these factors are extremely important for public health. In essence, the early detection of Avian Influenza enables countries to take swift preventive measures, thereby reducing the risk of viral transmission and spread.
Should Animals with Avian Influenza Be Culled?
Yes, both the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization of the United Nations (FAO) recommend the culling of domestic poultry. However, this is not the only solution for controlling and eradicating the virus. Other crucial factors in disease control include proper animal quarantine, restricting animal movement, strengthening biosecurity protocols, and strict surveillance in areas near an outbreak. The specific measures are not uniform across all affected regions. They can vary depending on the animal population, the epidemiological context, and access to animals, particularly those with high economic value.
Some countries around the world vaccinate their poultry before an outbreak occurs. Is Vaccination for domestic animals Recommended?
Some countries around the world vaccinate their poultry before a disease outbreak occurs. Is vaccination recommended for animals?
It is certain that vaccination against Avian Influenza in poultry is a crucial tool for controlling the onset of the disease and reducing mortality in birds. However, it’s important to note that countries must administer the most suitable vaccine based on the viral strain that is prevalent in their region. This technique is called a vaccination strategy. For instance, it involves determining which animal populations need to be vaccinated and ensuring that coverage is sufficient. It also includes monitoring for any potential transmission and tracking viral changes.
What Should Be Done to Prevent and Reduce the Risk of This Disease?
The best method is to control the Avian Influenza virus. All individuals who work with wild and domestic birds should have sufficient knowledge of biosecurity and biosafety. All workers and personnel involved in poultry production and breeding must be properly trained and familiar with the necessary protocols. In addition to knowing and following these protocols, workers in this industry should use appropriate protective equipment when handling birds, including specialized clothing, gloves, and masks. If you encounter a dead, dying, or sick wild or domestic bird, you must strictly avoid touching it and immediately report the case to official veterinary services.
