Chicken diseases interfere with productivity and the growth of chicken and are a serious threat to the profitability and sustainability of the venture. Many aspiring poultry farmers give up their projects due to the challenge of diseases. Here are the top common diseases, the signs to look out for and the remedies.
1. Newcastle Disease
Cause: This is a highly contagious virus called Newcastle Disease Virus (NDV). It is a deadly chicken disease globally. It causes respiratory and nervous disorders in chickens and other birds. Chickens are readily infected by aerosols and by ingesting contaminated water or food.
Infected chickens and other domestic and wild birds may be sources. The main methods of virus spread to healthy flocks are contact with infected birds, faeces and contaminated equipment or litter.
Symptoms: Affected birds will gasp for air, cough, sneeze, and have tremors, paralyzed wings and legs, twisted necks. They will also exhibit complete paralysis, watery greenish diarrhoea and significant drop in egg production. Eggs may be abnormal in colour and shape.
Prevention and treatment: Vaccines are used to induce an antibody response. Vaccinated birds must be exposed to a larger dose of the virus to be infected. Routinely boost their vaccination three months thereafter.
2. Fowl Pox
Cause: This infection is caused by the Avipox virus. Poultry carrying this virus can spread it to other birds through wounds. It can even spread it to nearby poultry houses.
Symptoms: They are two forms of the disease; the cutaneous or dry and the diphtheritic or wet. Both may be present in the same flock or animals.
The dry form shows as a pimple or scab on skin mainly comb, wattles, eyelids and other unfeathered portions of the body.
The wet-mucous form shows diphtheritic, cankers or yellow lesions in the mouth, oesophagus or trachea. Others signs are blindness, poor appetite, low egg production and facial swelling.
Prevention and treatment: Feed chicken on soft food and give them a warm and dry place to recoup. Chances are high that your birds will survive if given adequate care. Vaccination effectively prevents the disease and may limit spread within actively infected flocks. Vaccination with an attenuated vaccine of cell-culture origin in the first few weeks of life and re-vaccination at 12–16 weeks is often sufficient.
3. Avian Influenza or Bird flu
Cause: This disease is caused by Avian Influenza virus. Transmission is through contact with birds who are carriers.
Symptoms: The signs include respiratory troubles and birds will stop laying. Sick birds also develop diarrhoea. There may be swelling in the chicken’s face and their comb and wattle may be discoloured or turn blue.
Prevention and treatment: There is no vaccine. Practice of exclusion bio-security strategies to prevent introduction of AI into poultry is the best preventive measure. If it infects a chicken, it will always be a carrier. Wild animals can even carry the disease from bird to bird.
Once your birds get this disease, they need to be killed and the carcass burnt or buried. Sanitize all areas that the birds were, before introducing a new flock. Be careful because this disease can make humans sick.
Affected flocks can be treated with broad-spectrum antibiotics to control secondary pathogens.
4. Infectious Bronchitis
Cause: The disease is caused by the avian infectious bronchitis virus (IBV).
Symptoms: Infected birds will sneeze, snore, and cough and afterwards will produce fluids from their nose and eyes. Chicks may cough, sneeze and have facial swelling. The feed consumption and weight gain will be compromised. Other signs are depression, ruffled feathers, wet droppings and finally death.
In layers, egg production may drop by as much as 70 per cent, and the eggs are often misshapen, with thin, soft, wrinkled, rough and pale shells. They are also smaller.
Prevention and treatment: Vaccination is the best preventive strategy. However, if you decide not to use a vaccine, quarantine as soon as you notice symptoms of the disease in chicken. Antibiotics therapy may reduce mortalities caused by complicating bacterial infections.
To treat Infectious Bronchitis, give your chickens a warm and dry place to recoup.
5. Marek’s Disease
Cause: Marek’s disease is caused by a virus belonging to the Herpes virus group. They actually obtain the virus by breathing in pieces of shed skin and feather from an infected chick. This disease is very easy for them to catch.
Symptoms: More common in younger birds that are usually under the age of 20 weeks. Tumors begin to grow inside or outside of your chick. Their eyes turn cloudy and they no longer respond to light. They become paralysed.
Prevention and treatment: There is no effective treatment for Marek disease. Prevention methods include vaccination, biosecurity, and genetic resistance. Vaccination is the best prevention strategy, along with strict sanitation to reduce or delay exposure.
[The writer is the resident vet, FarmKenya Initiative]