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Managing Newcastle disease outbreak

By Dr Watson Messo

Newcastle disease or Kihuruto affects domestic chickens and wild birds in equal measure. It is a viral disease and has no cure. Once infected, no antibiotics can cure this ailment.

Ways of infections

The disease-causing organisms live in wild birds like pigeons, parrots and pheasant, from where infections are transmitted through nasal droppings, to our domesticated chicken.

Contamination of our chicken feed and raw materials is another route of infection. It is also increasingly common to pick up infections, when your shamba boy/worker visits kienyeji chicken sales point and dashes back into the chicken house without change of clothing and footwear. It is worse if you do not have a footbath with clean fresh disinfectant as a last barrier into your flock units. Most kienyeji/village chickens are not vaccinated against Newcastle disease and will continue to pose a threat of huge magnitude to our population of chickens reared for commercial purposes. It is therefore mandatory that commercial farmers who have invested heavily in the poultry sector strive to avoid completely any form of contact with the wild birds and non-vaccinated village chickens.

Most common signs

Although it affects birds of all ages, it is more common in young birds. 5 to 6 days after introduction into non-vaccinated chickens, the birds will show the following respiratory signs: gasping for breath, coughing, and sneezing, depending on the severity of the offending organisms. This will be evident at night when temperatures are low, and curtains closed. 

There are also signs associated with inflammation of the eye membranes like wet, thick eyes, stuffy nasal cavity and swollen sinuses and heads.

In severe cases, the only sign is massive deaths of flocks.

If the nervous system of the birds is involved, there will be tremors, some birds will show twisted necks, birds appear as if they are watching the stars (star gazers), some will be circling a couple of times and then resume a normal posture.

Such birds have completely reduced appetite, lose weight and pass out greenish watery diarrhea. These birds die in a couple of weeks.

Since most respiratory diseases present similar signs and symptoms, a poultry farmer should always talk to his/her vet immediately mortality increases or if production, feeding or drinking dwindles. Further laboratory tests will be required to confirm illness. 

Prevention and control

Vaccination

The good news is we have vaccines available that if properly and frequently used will effectively induce immunity against Newcastle disease and bring a stop to this condition.

Farmers should as a matter of routine either buy Newcastle vaccinated day-old chicks or do vaccinations immediately at placement on day one. This is called priming dose; a booster dose is required again at 7-14 of age for all types of birds through mass application through drinking water or spray. In some areas where Newcastle disease outbreaks are common, a third booster can be done at 21-24 days. In slow growing birds, a killed injection Newcastle vaccine is recommended at week 6-8 for prolonged protection.

All vaccinations are by law carried out by competent vet surgeons registered by the board or by veterinary para-professionals. A quick consultation with your chick supplier of the most appropriate vaccination program is important.

Bio-security

After vaccination, you need to keep your flock healthy. This can only be done by keeping disease causing organisms outside the door. Make a list of all possible things that routinely can get into the flock units.

These will include water, feed, feeders, drinkers, wood shavings, workers, visitors, air, insects, wild birds, small tools, rodents etc. From this endless list, declare that you will only allow entry into the flock unit, those things that are necessary for survival of your birds. Those items that must go into the flock unit, should only do so via the compulsory decontamination process.

Provide clean uniforms and boots, erect foot baths at the doors, carry out bird proofing and practise good rodent control. Keep away unnecessary visitors and lock your doors all the time.  

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