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鸡蛔虫Ascaridia galli

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Ascaridia galli is a parasitic roundworm（寄生蛔虫） belonging to the phylum Nematoda（线性动物门） .

Nematodes of the genus Ascaridia（禽蛔属）  are essentially intestinal parasites（肠道寄生虫） of birds.

 A. galli is the most prevalent and pathogenic species （致病性） , especially in domestic fowl （鸡） .

It causes ascaridiasis, a disease of poultry （家禽） due to heavy worm infection, particularly in chicken and turkeys （火鸡） .

It inhabits the small intestine （小肠） , and can be occasionally seen in commercial eggs.

Introduction

Morphology

头部顶端a prominent mouth which is surrounded by three large tri-

lobed lips.

Anterior end（前端）

Posterior end of female ( 雌虫尾部 )

Posterior end of male ( 雄虫尾部 )10 Sex papilla( 性乳突 )There is a preanal sucker( 肛前吸盘 ) before coacal pore( 泄殖孔 )

Anus( 肛门 ) at the end of the worm

There are two ventral lip( 侧腹唇 ) ， esophagus( 食道 ) ， nerve ring( 食道环 )

The development from egg to adult  needs 5~8 weeks.

Adult life span is about 1 years

Earthworms become  storage host with swallowing  their eggs

Eggs containing infective larvae

Infective eggs

Adults parasitize in the small intestine

Life cycle

适宜环境：

3 周时间发育成含幼虫的感染性虫卵

small intestine( 小肠 )

Duodenum

( 十二指肠 )Development for some time into the intestinal mucosa（进入肠黏膜发育一段时间）

Back to the intestine( 返回肠腔 ) Development

time( 发育一段时间 )

To be adult

( 成为成虫 )

Epidemiology

Ascaridia galli infection occurs in the rearing chickens, and the chickens kept in cages Is less common.

The nematode infects fowl of all ages, but the chickens at three months of age is most susceptible and the disease is more serious .

Heavy infection is the major cause of weight depression and reduced egg production in poultry husbandry.

In severe infections, intestinal blockage can occur. Unthriftiness, drooping of the wings, bleaching of the head and emaciation. It also causes loss of blood, reduced blood sugar content, increased urates, shrunken thymus glands, retarded growth and greatly increased mortality.

In heavy infections, adult worms may move up the oviduct and be found in hens' eggs, and sometimes they are also found in the birds' feces.[11]

Symptoms

出血性肠炎

虫体聚集阻塞肠

管

Depression( 精神沉郁 ) 、 pale mucosa( 黏膜苍白 )

Disheveled feathers （羽毛蓬乱）、 Dysplasia （发育不良 ) 、 Slow( 行动迟缓 )

顽固性下痢

LesionsAffected with early phase, the intestinal mucosa of chicken always appear bleeding or hyperaemia （充血、出血） and edema（水肿） .The larva （幼虫） forms parasitic tubercle in parasitic location, even arouse intestine rupture （肠破裂） , peritonitis  （腹膜炎） . By cutting intestinal tract, a large amount of parasites can be discovered. 

Definite diagnosis :

floating method with saturated salt solution ( 饱和盐水浮集法 )

or discovering large number of the parasite（虫体） when cutting the small intestine （小肠） at autopsy （剖检）

根据粪便中发现虫卵或剖检时在小肠内发现大量虫体

Diagnosis

Treatment and Control 1 、 Treatment : praziquantel( 吡喹酮 ) albendazole( 丙硫苯咪唑 ) Fenbendazole( 芬苯达挫）

2 、 Comprehensive prevention( 综合性预防措施 ):I Regular de-worming Improvement of breeding and management . Improve hygiene and the resistance Harmless disposal of feces

References 李国清 .兽医寄生虫学 (双语版 ).北京 :中国农业大学出版社 ,2006

Ackert, JE (1940). "The large roundworm of chickens". Vet. Med. 35: 106–108

Ashour, AA (1994). "Scanning electron microscopy of Ascaridia galli (Schrank, 1788), Freeborn, 1923 and A. columbae (Linstow, 1903)". J Egypt Soc Parasitol 24 (2): 349–55.