多头蚴 Coenurosis 病原形态（ Morphology ） 生活史（ Life cycle ） 流行病学（ Epidemiology ） 症状（ Symptoms ） 病变（ Lesions ） 诊断（ Diagnosis ） 治疗（ Treatment ） 预防（ Prevention ）

多头蚴病是寄生在犬及其他野生肉食兽小肠中 的多头多头绦虫 (Multiceps multiceps) 的幼虫 — — 多头蚴 (coenurus) ，寄生在牛、羊的中枢神 经系统而引起的重剧寄生虫病。 Ceonurosis( 多头蚴病 ) is a parasitic disease caused by Multiceps multiceps( 多头多头绦 虫 )which is parasitic in the small intestine( 小肠 ) of dogs and other kind of wild carnivorous animal. When the coenurus is ingested by cattle, goat and sheep, it will infect the CES(central nervous system, including the brain and the spinal cord ).It can cause high death rate in goats and sheep.

Morphology Larval stage——coenurus( 多头蚴 ) Shape: cyst( 囊 ) full of transparent liquid Size: about 2-3mm. There are many protoscolexes( 原头节 ) growing on the intine( 内壁 ) of the cyst membrane( 囊膜 ).

Length ： cm; Width:3-6mm Scolex: pear shape, 4 suckers, rostellar hooks on the rostrum in circle. Mature proglottid: square, about 200 testis distributing in between both sides of excretory ducts( 排泄管 ) ， the ovary divided into two leaves---the big one and the small one. Gravid proglottid: length:8—10mm, width:3—4mm. the uterus( 子宫 ) is full of eggs （虫卵）. Multiceps multiceps( 多头多头绦虫 )

Life cycle Intermediate host （中间宿主） : sheep, goat, cattle, pig, etc. Parasitic site: brain, spinal cord （脊髓） Definitive host （终末宿主） : canid, wolf, fox, etc. Parasitic site: small intestine （小肠）

Adult is parasitic in the intestine of dog, wolf, fox or other kind of wild carnivorous animal. When Gravid proglottids are eliminated from host, eggs can spread on the ground of pasture( 牧场 ) or cause the pollution of drinking water and fodder （饲料）. Eggs can be absorbed by the intermediate host like goat or sheep through the polluted water and fodder. When it reach the gastrointestinal tract( 胃肠道 ), the onchosphere( 六 钩蚴 ) escapes from the egg and drills into the blood vessel( 血管 ) of intestinal mucosa( 肠粘膜 ). Along with the blood, it flows to the brain. After 2 or 3 months later, it grows into coenurus. However, the onchosphere( 六钩蚴 ) flowing to other part of the body will die soon.

Epidemiology Ceonurosis has a major epidemic in the developing countries in Africa and Southeast Asia. It’ s also popular in some pastures in northwest and northeast China.

Symptoms In chronic cases( 慢性病例 ), we can see some particular symptoms, such as movement incoordination and walking in circle. Depending on the parasitic site, it will show different symptoms.

Frontal lobe( 大脑额叶 ), parietal lobe( 大脑顶叶 ): Infected host will bow its head, run forward, hold out against( 顶住 ) something without any movement or make forced movement( 强迫运动 ) to the offside of the infected area. Causing vision disorder and the pupil( 瞳孔 ) not reacting to the light reflex( 光反射 ). Occipital lobe( 大脑枕叶 ): Movement incoordination, lying on the ground, head hypsokinesis( 头常后仰 ), blindness( 失明 ). Cerebellum( 小脑 ): movement incoordination, lying on the ground, posterior paresis( 后肢麻痹 ).

Lesions In acute deaths ( 急性死亡病例 ), it shows some lesions like meningitis( 脑膜炎 ) and encephalitis( 脑炎 ). When it comes to the later stage of the disease, you can find one or more coenuruses ( 多头蚴 ) in the surface of the brain or spinal cord during the autopsy ( 尸体剖检 ). You can also find it deep inside of the brain. The cranium( 颅骨 ) connected with the infected area will become thin, soft and even have perforation( 穿孔 ).

Diagnosis Clinical diagnosis: Ultrasonic detection(B 超 ), X-ray, CT scan, MRI. Immunology diagnosis: IHA, ELISA, etc.

Treatment Pharmacotherapy( 药物治疗 ): Praziquantel ( 吡喹 酮 ), albendazole ( 丙硫咪唑 ) Surgical therapy ( 手术治疗 ): In the later stage of the disease, we can locate the parasitic site with some technique like X-ray(X 光 ) or ultrasonic detection(B 超 ) and remove the coenurus( 多头蚴 ). However, when there are too many coenuruses( 多头蚴 ), we can inject ethyl alcohol( 乙醇 ) in the cyst ( 囊 ) to kill the coenuruses.

Prevention Dogs should be deworm periodically. Canid dog, wolf, fox should be caught and killed. Do not let the dog eat the brain or spinal cord taken from the infected cattle or sheep.

小组成员：陈杰 陈昊天 陈旭贵 符其忠 李海云