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POULTRY DISEASES

Updated: Oct 24, 2019

Most people in Kenya are adopting commercial poultry keeping as a means of generating additional income.


In the past few years, commercial poultry production has been on a steady growth despite the numerous challenges.


These challenges include;

  • rising cost of poultry feeds,

  • fluctuations in the supply of day-old chicks,

  • low-quality poultry health inputs,

  • insufficient knowledge in poultry diseases management

  • and poor access to market due to unsynchronized commercial poultry production.

One of the major challenges that cut across both the exotic and indigenous poultry farming is the issue of disease control and management.


Most farmers have not adopted the practice of disease control interventions such as vaccination and proper poultry management practices.


This is especially so amongst indigenous poultry farmers who think that vaccinations should only be for exotic commercial birds.


This article will focus on the management of New Castle disease.


New Castle Disease


Causative agent: Newcastle Disease is a fast-spreading poultry disease that affects poultry of all ages. It is caused by a virus known as Paramyxovirus which is of variable pathogenicity.


The disease presents with signs the nervous, respiratory or reproductive systems. Morbidity is usually high and mortality varies 0-100%.


Higher death rates are seen in the unvaccinated stock.


Affected species include chickens, turkeys, pigeons and ducks.


The condition is rarely diagnosed in ducks but is a possible cause of production drops/fertility problems.


Transmission is via aerosols, birds, fomites and visitors. It is not usually vertical (but chicks may become infected in hatcheries from contaminated shells.

The virus survives for long periods at ambient temperature, especially in poultry droppings and can persist in houses (in poultry droppings, dust etc) for up to 12 months.


However, it is quite sensitive to disinfectants, fumigants and sunlight. It is inactivated by temperatures of 56°C for 3 hours or 60°C for 30 min, acid pH, formalin and phenol, and is ether sensitive.


Clinical Signs


Signs are highly variable and will depend on the infective dose and the degree of immunity from previous exposure or vaccination.


  • Sudden Death –The farmer wakes up in the morning or comes in the evening and finds birds that have died suddenly without showing any clinical signs.

  • Depression-a bird is found standing alone in the corner of the poultry house.

  • An inappetence-the bird will not feed or drink water.

  • Coughing.

  • Dyspnoea.-Difficulty in breathing.

  • Diarrhoea-Loose chicken dropping.

  • Nervous signs.-Lack of balance or inability of the birds to stand on its feet.

  • Paralysis.

  • Twisted neck.

  • Severe drop in egg production.



Management: Call in a veterinary doctor once you notice these clinical signs. The doctor will then carry out further disease investigations and come up with the definitive diagnosis.



Preventing the Spread of Newcastle Disease


A. Isolation refers to the confinement of animals within a fence, which keeps your birds in, but it also keeps other animals out.


1) Prevent the introduction of new birds to a previously infected facility for 2-3 weeks after a complete cleanout.


2) Clean out vegetation around poultry houses and pens to remove shelter and food for possible carriers of the virus.


3) Institute a control program for insect, mammalian, and avian vectors, which are important because they carry infections to new birds.


If possible, keep birds in closed but well-ventilated houses rather than exposed to wild birds.


4) Prevent the accumulation of standing water. This is a great attraction to migrating birds, which can carry Newcastle Disease Virus.


5) Limit sources of food for wild and free-flying birds. Cover all feed storage. Clean up spills when they happen.

6) Do not to visit live bird markets or other places where there are birds that could carry Newcastle Disease Virus.


7) Avoid dead wild, domestic or free-flying birds you find or are brought to you. Any found on your premises must be treated as though they are highly infectious. Handle them with gloves, place in a plastic bag, and seal it, finally, shower and change clothes before entering poultry facilities again.


B. Traffic control includes both the traffic onto your farm and the traffic patterns within the farm.


1) Be a good neighbour. If you have or suspect Newcastle disease, initiate a self-imposed quarantine.


a) Most critically, stop all movements of people


b) Get birds (some sick and some dead) to the District Veterinary Office or a diagnostic laboratory near you where you will get advice.


2) Keep human farm-to-farm traffic to a minimum. Conduct business by phone when possible.


3) Find out where someone has been before inviting them to visit your flock. Shoes and clothes can carry Newcastle Disease Virus so, it is best to provide plastic boots and coveralls to all visitors.


4) Isolate dead bird disposal away from your flock. Never walk from this area back to your flock. Protect carcasses from predators and take them to the District Veterinary Office or a diagnostic laboratory as soon as it is reasonable.


C. Sanitation means the disinfection of people, and equipment entering the farm and the cleanliness of the personnel on the farm.


Cleaning and disinfection


Newcastle disease virus (NDV) can survive at room temperature for days to months.


However, NDV is sensitive to most disinfectants and can be readily inactivated if a surface is properly cleaned first then disinfected using Formaldehydes and Hypochlorites such as bleach or jik.


Prevent the spread of Newcastle Disease Virus on equipment


1) Make sure that any vehicles coming near your flocks are not contaminated with litter or faeces. Wash and disinfect the tyres and wheels of all vehicles coming onto your premises.


2) Wash with detergent and disinfect all bird manure handling tools, equipment, and vehicles.


3) Enclose all dead birds to be taken to the laboratory in plastic bags.


Confine live birds being submitted to the laboratory in boxes that will not return to your farm.


Disinfect any vehicles returning from the laboratory including the floor mats.


Do not let anyone who has been to the laboratory return to your flock without a shower and a change of clothes.


General comments


1) Spray a facility with a disinfectant after complete depopulation to remove NDV from an infected facility.


At the same time, a vector control program should be instituted, followed by removal of manure, cleaning of all surfaces followed by a second application of a disinfectant.


All manure should be removed and all surfaces thoroughly dry cleaned prior to applying disinfectants.


Next, apply the disinfectant to all surfaces twice, allowing the disinfectant to dry between applications.


The house should be left empty for 2-3 weeks before repopulation.


NB; The Newcastle disease virus is sensitive to many disinfectants. However, it is very difficult to inactivate the virus if it is inorganic material, such as faeces. Therefore, it is very important to use a combination of both cleaning and disinfection to get rid of this virus



References

http://kenyapoultry.org/partners/34-mold/51-poultry-diseases-management-on-farms.html

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