What is Avian Influenza?
Avian influenza (AI), popularly known as bird flu, is a highly contagious viral disease that affects domestic and wild birds. Avian influenza causes more harm to free-range poultry birds if they have contact with migratory birds, wild waterbirds, and shorebirds, which have a natural resistance to the avian influenza virus.
As shown by experience, when the AI virus breaks out in a poultry farm, it can lead to a high mortality rate of about 50%.
 |
| Avian influenza: cause, symptoms, and control in poultry farm |
What Causes Avian Influenza?
Avian influenza is caused by the Avian Influenza Type A virus infection. The AI virus is divided into 16 hemagglutinin (H1 – 16) and nine neuraminidase (N1 – 9) subtypes which are either in low pathogenicity (LP) or high pathogenicity (HP). Pathogenicity is the ability to cause disease.
LP avian influenza viruses that occur more frequently cause milder diseases like subclinical infections, respiratory disease, or drops in egg production. Compared to LP, HP avian influenza viruses occur less regularly. They cause severe systemic disease with multiple organ failure and mortality rates of up to 100%.
AI Virus Symptoms in Chickens
The AI virus is a highly contagious viral disease that can spread very easily and quickly among your flocks. The incubation period ranges from as short as a few hours to three days in an individual bird and 14 days to spread throughout your whole flock.
The high mortality rate of the AI virus affects both your poultry production and your financial returns. It is essential as a farmer to know what to check for in your flocks to prevent the spread of the virus among your flocks. Some of these symptoms are:
1. Nasal discharge
2. Lack of coordination
3. Coughing and sneezing
4. Lack of energy and appetite
5. In laying hens, decreased egg production
6. Lack of energy and appetite
7. Soft-shelled or mishappen eggs
8. Swelling of the head, eyelids, wattles, hocks, and comb
Noticing any of these symptoms is a tendency of the bird flu in your flock, coupled with the death of a bird without any warning signs.
Control
The primary cause of the AI virus within your farm is the direct contact of your birds with a migratory or water bird which are natural carriers and have resistance to the virus. Also, when your healthy bird has contact with a surface infected by the droppings of these unaffected carriers.
The virus can survive for a short period of 2 weeks or as long as two months on materials such as glass, wood, steel, soil, and chicken feces with low temperature and humidity.
Apart from direct contact with the virus or a carrier, humans can be a secondary cause of this virus to healthy birds. Preventive measures must be in place to prevent the spread of the virus, as treatment with antiviral compounds is not approved or recommended.
Some of the preventive measures are:
1. Regularly have your birds tested
2. Do not use or borrow equipment from other poultry farms
3. Closely monitor your bird's behavior, appearance, and appetite
4. Limit access to birds to only the necessary personnel
5. Cut off access of your birds with contact with outside wild birds
6. Thoroughly clean all your equipment used to clean your birds' houses and vehicles used to move your birds
7. Isolate birds that show symptoms for at least 30 days
8. Report suspected outbreaks to the appropriate regulatory authorities
Vaccination against AI can supplement preventive measures carried out after detecting the disease. Antigenically matched and properly administered vaccines can prevent clinical signs, death, significantly reduce virus replication and shedding from the respiratory and gastrointestinal (GI) tracts.
The primary cause of the AI virus is direct contact. Still, you can also spread the virus among your birds, so always avoid touching or picking any dead, visibly sick, or injured wild bird, as wild birds are susceptible to many diseases.
The farmer should prevent the AI virus at all costs. Suppose the farmer does not control the AI virus. In that case, an outbreak can lead to high mortality. Regulatory authorities will be permitted to humanely cull infected birds in your poultry, which is presently happening in England.
Always ensure preventive measures within your poultry farm to protect the public, and maintain the safety of world trade in animals and animal products.