Prevention and treatment of Chicken Encephalomyelitis

Chicken Encephalomyelitis (AE) is an infectious disease of chickens caused by avian encephalomyelitis virus, which mainly affects the nervous system, also known as epidemic tremor. The main characteristics of the affected chicks are ataxia, head and neck muscle tremor, leg paralysis, paralysis, etc., while laying hens show a decrease in laying rate.

First, symptom 1, chicken. At the initial stage of the disease, the affected chickens were depressed and slow to respond; then some of the diseased chickens developed ataxia and refused to move; or their gait was unstable until they could not stand; they landed with their hocks on the ground and their wings spread out to the ground, barely flapping their wings to assist in moving forward, or even completely paralyzed; some of them suffered from chicks, head and neck tremors, especially when they were stimulated, the tremors intensified. The affected chickens still have an appetite in the course of the disease, but they are often unable to eat and drink because of complete paralysis, resulting in exhaustion and death. The course of the disease is 5-7 days. 2. China Chicken. A small number of chickens fell ill, and the sick chickens showed stiff soft feet and even central nervous system disorders; the affected chickens tilted their heads and extended their necks to walk in a straight line, or went backwards, or suddenly turned their heads to the left and right for no reason. Individual affected chickens may develop unilateral or bilateral opacity of the lens, or even blindness. 3. Adult breeder chickens. No neurological symptoms, mainly showed a transient decline in egg production. The egg laying rate generally dropped by 10% to 20%, and returned to normal after about 14 days. The quality of eggs is mainly due to the decrease of hatching rate, most embryos die around 19 days old, and hens may lay small eggs, but there is no significant change in egg shape, color and content.

Second, there are some mottled gray-and-white areas in the muscle section of the muscle stomach of the affected chicks. Opacity appears in the lens of the eyeball. Histopathological examination showed dissolution of central chromatin of neurons in brainstem medulla oblongata and gray matter of spinal cord, "cannula" around blood vessels in the brain, focal proliferation of glial cells, and a large number of lymphocyte infiltration in myogastric and pancreas.

3. The main points of clinical diagnosis of this disease are the obvious ataxia and tremor of head and neck muscles in chicks at the age of 1-2 weeks after birth, and the recent history of decreased egg production in their hens. Brain stem, spinal cord, myogastric and pancreas can be examined if necessary.

Fourth, to prevent and control this disease, we must adhere to the policy of "prevention first". At present, there are two kinds of vaccines used in immunization: avian encephalomyelitis "canek114 strain" live attenuated vaccine and avian encephalomyelitis oil emulsion inactivated vaccine. The basic immune procedure is as follows: first immunization, live attenuated vaccine (1 / 2) at the age of 12 weeks, and live attenuated vaccine (2 / 16) at the age of 16 weeks, at the same time, oil emulsion inactivated vaccine 0.5~1ml/ can be injected intramuscularly. Through the above immunization, the immunization period can reach more than one year, and if necessary, the breeder chickens can be intramuscularly injected with oil emulsion inactivated vaccine in the middle of laying eggs, or the oil emulsion inactivated vaccine can be used for emergency vaccination when breeder chickens get sick.