Newcastle disease in poultry: what farmers need to know

23 Aug, 2015 - 00:08 0 Views

The Sunday News

AFTER a discussion with a colleague on mortalities recorded in her mother’s brood of chickens I thought I should pen an article detailing one of the most economically important diseases in poultry production. This is the Newcastle disease. It is a notifiable disease which means you need to inform your local veterinary office if you suspect that your chickens could be affected by the disease.

Newcastle disease is a viral disease of birds with a wide range of clinical signs from mild to severe.
This disease is caused by a diverse group of viruses. The milder strains are endemic in the United States, while highly virulent strains are found in Africa and Asian countries.
The highly virulent form of Newcastle disease is one of the most important poultry diseases worldwide. Chickens are particularly susceptible, and may experience morbidity and mortality rates of up to 100 percent.

Outbreaks of virulent Newcastle disease have a tremendous impact on backyard chicken industries especially in developing countries, where these birds are a significant source of protein and this disease is endemic.
It is the most important poultry disease in Southern Africa.

It is highly contagious, which means that it spreads rapidly among chickens infecting a large number of your birds within a short time.
It has a high death rate such that a farmer can wake up to find 50 birds dead overnight. It affects any kind of poultry farmers from smallholder, communal to large scale commercial producers.

Intensive management of poultry where large numbers of chickens are housed together as well as the transportation of chickens over long distances promotes the spread of the disease.

The virus is present in the droppings of sick as well as healthy chickens that are carriers of the virus.
Healthy chickens are infected when they eat food or drink water contaminated by the droppings from sick chickens.
Chickens are also infected by breathing in small airborne droplets that originate from sick chickens and from healthy chickens that carry the virus.

The virus can live for some time outside chickens and the disease can be spread by the movement of poultry, people, equipment and poultry products from one area to another.
Affected chickens rapidly become weak and often die without showing any signs. However, some signs may include depression which is characterised by a chicken with a dull “mood” and is not lively.

The chicken may also have ruffled feathers as compared to a generally smooth plumage of healthy birds. Layers will experience a sudden and significant drop in egg production.

The eggs are of poor quality, have soft shells and may also be deformed with watery egg whites. The bird may exhibit nervous signs and this is due to the effects of the disease on the nervous system of the birds.

One typical nervous sign is that of birds walking in circles. The birds may also have their heads turned facing backwards or the head may be held between the legs.

The affected chickens generally experience difficulty in walking with muscle twitching and in extreme cases paralysis may result.
Observable signs of the disease from the guts of affected birds include green diarrhoea and this may also be observed from the droppings of sick birds. As a result of infection in the respiratory track the birds will have a laboured and rapid breathing. This may also be coupled with coughing and swollen sinuses may be visible.

In dead birds, the carcases are usually in good condition but there may be bleeding in the stomach and gut.
There may be small red spots on fat around the heart or intestines and watery contents in the nose and sinuses. The windpipe may be red or show small red spots on the inside.
There is no treatment for Newcastle disease and sick birds are usually destroyed to avoid spreading infection to other birds.

However antibiotics may be given to control secondary infection. This is a controlled disease and therefore it is very important to contact your veterinary officer immediately if you have suspected cases.

They will then help to control it and prevent it from spreading. Control measures will include quarantine, emergency vaccination, disinfection and burning of chicken litter and dead chickens.

The best way to prevent the disease is by good management and vaccination. Vaccines are available to protect chickens against Newcastle disease. Only healthy chickens should be vaccinated. This is a very serious disease which can easily wipe off all your chickens be they broilers or indigenous ones hence it is paramount to invest in good poultry management practices to avoid unnecessary losses.

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