Avian Encephalomyelitis (AE)
Avian encephalomyelitis (AE) is a woldwide viral disease caused by a virus from the Hepatovirus family. It has been reported from virtually all developed countries, including New Zealand, Australia, USA and New Caledonia.
Susceptible are ...
It affects young chicken, Japanese quail, turkeys, and pheasants. The disease does not affect humans or other mammals.
Even though chickens of all ages are susceptible, clinical signs of encephalitis only develop in those younger than four weeks. The disease progression is similar in turkeys and chickens.
Transmitted both through the egg and by direct contact. Eggs laid by hens with sub-clinical infection will carry the virus. While hatchability drops, eggs will hatch and chicks will develop clinical disease soon after. Affected chicks shed virus in feces and will infect other chicks.
Can also be introduced through the import of sub-clinically infected adult breeding stock, infected day-old chicks or hatching eggs.
It is characterized by an initial dull expression of the eyes followed by ataxia (a neurological sign and symptom consisting of gross lack of coordination of muscle movements), tremor of the head, neck and limbs.
- Progressive ataxia - losing control of legs, sitting on its haunches and falling onto its side.
- Muscular tremors are best seen after exercising the bird; holding the bird on its back in the cupped hand helps in detection.
- Tremor of the head and neck
- Eventually paralysis and death from inability to feed or drink, or through being trampled.
- Some birds recover, and others may survive with persistent clinical signs.
- In susceptible adult birds, infection is usually sub-clinical, although there may be a transient drop in egg production.
Signs commonly appear at 7-10 days of age, although they may be present at hatching or delayed for several weeks.
Typically, about 5% of the flock is affected, although morbidity and mortality may be much higher.
The disease in adult birds is inapparent except for a transient drop in egg production. The disease in turkeys is often milder than in chickens.
Similar Diseases / Conditions:
- Nutritional Deficiencies:
- Avian encephalomyelitis (vitamin E deficiency)Vitamin A deficiencyRiboflavin deficiencyRickets (caused by a lack of vitamin D, calcium or phosphate)
- Marek's Disease
- Newcastle disease
- Eastern encephalitis (transmitted by the bite of an infected mosquito)
- Encephalitis caused by bacteria, fungi (eg, aspergillosis)
Prevention and Treatment:
NEED A VET?
USA: Find Your Local Avian Veterinarian
Information contained on this website is provided as general reference only. For application to specific circumstances, professional advice should be sought.
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