Introduction to Cestodes (tapeworms) Characteristic of class cestodes: ① endoparasitic, and the adults in the intestine; ② dorso-ventrally flattened and bilaterally symmetrical and like a piece of tape, consists of a head with sucking organs and a long chain of segments; ③ without intestinal canal and body cavity; ④ hermaphroditic (雌雄同体)

Compare with Pseudophyllidea (假叶目) and Cyclophyllidea （圆叶目） Pseudophyllidea Cyclophyllidea Scolex 2 slit-like sucking 4cup-shaped suckers with or without hooks Genital on the flat surface on the margin of the pore of the segment segment Uterus present absent open Vetelline scattered all over condensed into a glands the segment single gland

I. Morphological characters

III. Life history 1.Adult live in intestine of vertebrate and larva parasite in tissue of vertebrate or non-vertebrate. 2.Cyclophyllidea requires two (or only one) host cysticercus egg→oncosphere→ cysticercoid →adult hydatid cyst alveolar hydatid cyst

3．Pseudophyllidea requires three host (one final host and two intermediate host) egg → coracidium → procercoid → ↑ ↑ ↑ into water into 1st into 2nd intermediate intermediate host host → plerocercoid → adult ↑ into final host

III. Classification Pseudophyllidea: Spirometra - S. mansoni Diphyllobothrium - D. latum Cyclophyllidea: Taenia T. solium T. saginata Echinococcus E. granulosus E. multilocularis Hymenolepis H. nana H. diminuta

Taenia solium（链状带绦虫） 猪肉绦虫，猪带绦虫、有钩绦虫 寸白虫

I. Morphology Adult : 2-4 m length, 700-1000 segments

Egg Cysticercus

II. Life History Adult Taeniasis (in small intestine) ingested by man Man Cysticercus Eggs, gravid segment (in muscle) (in faeces) by circulation Pig ingested by pig Onchosphere (penetrates intestinal wall)

Onchosphere

Cysticercus in pig muscle

(in muscle ) gravid segment (in faeces) by circulation Cysticercosis Adult (in small intestine) Man Cysticercus Eggs, (in muscle ) gravid segment (in faeces) by circulation Man ingested by man Onchosphere (hatches in intestine penetrates intestinal wall)

Notes: 1. Man is the final host and also can become the intermediate host; 2. Pig is the main intermediate host; 3. Infective stage: egg and cystercercus

III. Pathogenicity Taeniasis Cysticercosis intestinal descomfort: vomiting, diarrhoea or constipation, loss of appetite, appendicitis and intestinal obstruction Cysticercosis The methods of infecting eggs:  auto-infect oneself in body;  auto-infect oneself outside body;  infect from other person

Cysticercosis in brain Cystcercosis in eye Cysticercosis in subcutaneous tissues and muscles

IV. Diagnosis Taeniasis Cystisercosis stool examination anal swab gravid segment examination Cystisercosis biopsy funduscopy（眼底镜检查） X-ray, B ultrasonic, CT Serological tests

V. Epidemiology Geographical distribution Epidemic factor all parts of the world where pork of pork products are eaten Epidemic factor the method for feed the pig is not good bad eating and cooking habit

VI. Prvention and Treatment Treat the patient Binlang（槟榔）, pumpkin seed（南瓜子）praziquantel（吡喹酮）, noclosamide（灭绦灵） Health conduct and education Strengthen management of lavatory, improve feeding pig method Strengthen pork test

Taenia saginata (肥胖带绦虫） 牛带绦虫 牛肉绦虫，无钩绦虫，寸白虫

Fig 1 Morphology differences between T. solium and T. saginata

Fig 1 Morphology differences between T. solium and T. saginata

Fig 2. Life cycle compare between T. solium and T. saginata T. solium T. saginata Infective stage egg and cysticercus cysticercus Intermediate host pig cattle Pathogen stage adult and cysticercus adult

Diagnosis, epidemic and treatment are same as T. solium