For a farmer to get full benefits of his investments, labour and time on his chicken farm, he must have a healthy flock. With that in mind, knowledge of important diseases, their transmission, treatment and control is key.
Today, I will highlight the most important chicken diseases in Kenya. This include Newcastle disease, Gumboro, Infectious Coryza and Fowl pox among others.
1. NEWCASTLE DISEASE
- Newcastle disease: Signs, prevention and treatment
- How to reduce mortality on your new poultry farm
- How to get your day-old chicks off to a good start
- How to add value to your poultry and boost profits
What is it?
Newcastle disease is a highly contagious viral disease. It affects all poultry including chicken, ducks, turkeys, pigeons but chicken are the most affected. This disease wipes out the chicken flock of an entire village in a few days! It recurs once or twice per year in different areas of Kenya.
How do birds get the infection?
The disease is spread to chicken by direct contact with droppings or discharges from infected birds. Objects such as shoes, equipment, clothing and other materials contaminated with infected feces can spread the disease to new flock.
Signs in infected birds
Symptoms in chicken may vary from mild to severe disease. Disease severity depends on the type of virus and immunity of the birds. Affected chicken may show signs of coughing, sneezing, nasal discharge, depression and diarrhoea. In severe illness, other symptoms include swelling of the head, twisted neck and leg paralysis. In very severe cases, sudden death of birds occurs.
How do I protect my chicken?
The virus stays in the environment for a prolonged period. It is important to prevent birds from infection. This can be achieved through cleaning and disinfecting chicken houses and equipment. For commercial farms, there is need to restrict entry of people into the chicken house. Use of footbaths is also important.
Newly introduced birds should be isolated for several weeks before mixing into the flock. Since chicken are most affected, there is need to reduce contact between chicken and other poultry such as ducks, turkeys, pigeons and others.
This disease has no cure but fairly affordable vaccines are available in many agrovets. The vaccines are commonly administered through the eye, nostril or in drinking water.
Vaccination is done three times a year. The vaccine can be given to chicken of all ages. It is important to vaccinate only healthy chicken.
What to do when birds are infected
Isolate all the sick birds
Contact your vet immediately
Do Not
Slaughter and eat the sick birds
Sell the sick birds
- GUMBORO/INFECTIOUS BURSAL DISEASE
What is it?
It is a highly contagious viral disease that affects poultry but seen mainly in chicken. It particularly affects 3-8 weeks old chicken.
How do birds get infection?
Chicken get infection directly on contact with infected birds or indirectly through contact with material contaminated with infected feces.
Contaminated clothes, beddings, equipment and other materials can spread the disease to a flock. The virus causing this disease is stable in the environment and particularly difficult to eradicate once it infects a flock.
Signs in infected birds
Severity of the disease depends on the virus and age of birds. Two forms of the disease are encountered. Subclinical disease occurs when the virus infects birds less than 3 weeks of age.
When affected the birds show no clinical signs but are prone to other infections. The clinical disease occurs in birds of 3-6 weeks.
Signs include severe prostration, watery whitish diarrhea, soiled vent feathers, inflammation of the cloaca and death.
How do I protect my chickens from the disease?
Prevention of spread of the virus into your flock is vital. This can be achieved by restricting movement of people into the farm, footbath and wheel baths on farm entrance.
Isolation of new birds for observation before mixing with the flock.
Vaccines are available in most agrovets for protection of chickens against Gumboro.
These are administered via the eye or drinking water. Injectable vaccines are also available.
For commercial farms, it is important to buy chicks from farms that vaccinate their breeding stock against Gumboro so as to protect chicks during the first 10-14days post hatching.
It is important as a farmer to vaccinate your chicks following the vaccination schedule provided by the breeding farm. Most breeding farms recommend vaccination of chicks at 14 days and a booster at 24 days of age.
What to do when your birds are infected
There is no cure for the disease but support therapy such as multivitamins can be given to affected birds.
Isolate sick birds
Contact your vet immediately.
3.INFECTIOUS CORYZA
What is it?
This is a highly contagious bacterial disease that affects the respiratory system. It spreads among the flock at an alarming rate.
How birds get the infection
Chronically infected chicken and healthy carriers spread the infection to other birds. Chicken get infection through direct contact with infected birds. Chicken can also be infected through air and contaminated water. Congestion of birds in chicken houses and keeping birds of different ages perpetuates the disease.
Signs in infected birds
Infected birds show symptoms one to three days post infection and sickness may last 2-3 weeks in a flock. Birds show spots on the neck, the eyelids become swollen and closed with a creamy pus oozing from the eyes. There is swelling of the face and wattle.
In acute disease, chicken show symptoms of sneezing, nasal discharge, difficulty in breathing and noisy rales when breathing. Birds do not feed and may die from starvation. Egg production may be delayed in young pullets or severely reduced in producing hens.
How to protect your chickens from the disease
All in/all out programme is the best way to avoid this disease on commercial farms. Replacement of birds must be from those raised on the farm or those from clean farms. Vaccines are available to prevent infection
What to do when your birds are infected
Since it is a bacterial infection, use of antibiotics is effective in treatment. Use of sulphonamide trimethoprim is effective. Other antibiotics that can be used include Erythromycin and oxtetracycline.
4.FOWL POX
What is it?
A viral disease that causes painful sores on the featherless skin and/or the respiratory and digestive tract.
How birds get the infection
Chicken are infected through contact with scabs from infected birds or through blood-sucking insects such as mosquitoes. Mosquitoes remain infective for several weeks after sucking blood from infected chicken. The disease can persist in an infected flock for months to years.
Signs in infected birds?
Infected chicken take 4-10 days to show symptoms. Two forms of the disease may present. The dry form of the disease affects chicken skin in non-feathered areas such as comb, wattle, face and eyelids. The skin in these areas develop blisters which enlarge into painful yellow bumps and finally to dark coloured wart-looking scabs.
In this form, death is rarely seen and recovery occurs in 14 days. The wet form of disease affects the upper respiratory system, the mouth, eyes and throat. The birds have difficulty in breathing and eating and may die from suffocation and starvation.
How to protect your chickens from the disease
Restrict movement of people into and out of the farm, disinfection of equipment, watering and feeding troughs and quarantine new birds brought to the flock.
Control of mosquitoes and other blood sucking arthropods is also important.
Vaccines are available for use in day-old chicks and unaffected adult birds using the wing-stab method.
When your birds are infected
When your flock is infected, the first step is to prevent further spread. Isolate sick birds, clean and disinfect waterers, feeders and chicken house daily.
There is no cure for the disease but comfort therapy and preventive measures for secondary infections can be given to affected birds. Glucose, tetracycline and multivitamins can be administered in drinking water. Scabs can be treated with dilute iodine solution and ointment (sulfur powder and Vaseline) daily until the lesions heal.
[The writer is a PhD student at Jomo Kenyatta University of Agriculture and Technology and a Research Scientist at Kenya Agricultural and Livestock Research Organisation (KALRO) focusing on avian diseases in Kenya]
