Avian Encephalomyelitis

Avian Encephalomyelitis (AE) is a viral infection of the central nervous system affecting various species of poultry: chickens, turkeys, Japanese quails and pheasants.

The disease most often affects chicks between hatch – six weeks of age. Symptoms usually appear at 7-10 days of age, although they may be present at hatching or delayed for several weeks. After 6-weeks of age, chicks are usually protected due to their increased immune system response. In adults, symptoms are usually milder.

Cause

AE is a picornavirus, most commonly spread between hens and their chicks via the egg, but also from direct contact between vulnerable chicks and infected birds. The virus may be spread in droppings two to four weeks after symptoms have passed. The good news is recovered birds are immune and will no longer spread the virus, although a hen’s egg production is likely to be affected.

Symptoms

Symptoms appear in newly hatched chicks or @11 days after exposure
Dull eyes
Ataxia (loss of muscle coordination)
Tremors of the head and neck
Sitting on hocks
Drop in egg production
Decreased hatchability
Paresis (weakness and partial paralysis)
Decreased appetite/drinking
Weight loss
Morbidity 5-60%
Survivors may have ongoing coordination issues or develop cataracts at around 18-20 weeks of age, which appear as bluish lens opacity and impaired vision.

AE shares some of the same symptoms as Marek’s, Newcastle, ingesting toxins and vitamin deficiencies (e.g. A, D, E, riboflavin). It can even be mistaken for electrolyte poisoning. If your birds are taking electrolytes ensure they are being given the correct dosage.

If you want a definitive diagnosis invest in a necropsy which will provide the lab work required to do so.

Treatment

There is no cure
Provide supportive care to sick birds (i.e. isolation, food and water, electrolytes) as some may survive

Prevention

Practice good biosecurity and quarantine new birds
Buy birds from NPIP certified breeders
Although AE is considered rare, vaccinations are available (given at 9- 16 weeks)

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