Hymenolepis nana （微小膜壳绦虫） 短膜壳绦虫 Adult parasite in intestine of mouse and man, cause hymenolepiasis nana （微小膜壳绦虫病）

I. Morphology Adult mature segment gravid segment scolex

Egg

II. Life history 1. Direct infect and develop gravid segment swallowed hexacanth penetrates eggs by man （六钩蚴） in intestinal (in faeces) villus re-enters the cysticercoid adult lumen of the digestive tract

2. Auto-infect gravid segment direct hexacanth egg hatching (in intestine) cysticercoid （似囊尾蚴） adult

3. Development by intermediate host gravid segment swallowed by hexacanth egg intermediate host (in fleas blood (in faeces) eg. Fleas canal) cysticercoid swallowed adult (in fleas blood by man (in intestine tract) of man)

Notes: 1. Infective stage: egg, cysticercoid 2. Infective method: by eatting 3. Intermediate host: fleas （印鼠客 蚤、致痒蚤、犬栉首蚤） and mealworms （面粉甲虫）

III. Pathogenicity Mechanical injure （机械性损伤） by sucker, hook Poisonous action （毒性作用） by secreting of worm

IV. Diagnosis Faeces examination for eggs and gravid segment

V. Epidemiology 1. Geographical distribution : cosmopolitan 2. Man infected by swallowing the egg from food, finger, water contaminated or by swallowing intermediate host contain cysticercoid auto-infect when immunosuppression 3. Rat and mice are very important reservoir

VI. Prevention and treatment Treat the patient Improve the food and environment sanitation Extinguish rat

Echinococcus granulosus （细粒棘球绦虫） Character: 1. Adult lie attached to the mucous membrane of the small intestine of final host 2. Eggs in faeces of final hosts are infective to man and to herbivorous （草食性动物） hosts 3. The larval form is a hydatid cyst which is common in many species of herbivorous animals ’s liver and lungs

I. Morphological characters Adult: very small, have a head and 3 segments Egg: indistinguishable from the Taenia eggs

Hydatid cyst

II. Life history adult protoscolex final host egg hydatid cyst intermediate host onchosphere ingested circulation by man hydatid cyst onchosphere

Notes: 1. Infective stage to man is egg; 2. The intermediate host are herbivorous (sheep, cattle ect.) and man; 3. The final host is carnivores (dog, wolves ect.); 4. Hydatid cyst can be found in liver (69.9%), lung (19.3%), abdomen canal (3%), brain (0.4%), spleen (0.4%), kidney (0.3%) and other organs of man.

III. Pathogenicity This depends on the location and the number of hydatid cyst. The early stage of infection is asymptomatic. As the cyst enlarges, symptoms of a space-occupying lesion develop.

Symptoms ： 1. Local compression and stimulation symptom 2. Nodules 3. Allergic reactions and sometimes anaphylactic shock may occur if the cyst raptures. 4. Secondary infect

IV. Diagnosis X-ray, B ultrasonic, CT, autopsy, immunological test Note: diagnostic puncture of a hydatid cyst is a very dangerous

V. Epidemiology 1. Geographical distribution: cosmopolitan 2. Epidemic factors: (1) egg contaminated to environment; (2) close contact between man, domestic animal and environment; (3) internal organs of sick animal are fed to dog or discarded everywhere.

VI. Prevention and Treatment Treat the patient Health conduct and education Regular vermifugal （驱虫） treatment to domestic animal Strength management to massacre （屠宰） of cattle and sheep, strength quarantine （检疫） of hygiene.

Echinococcus multilocularis （多房棘球绦虫） Notes: 1. Adult, not in man, but in foxes, wolves and less commonly in cats and dogs. The worms lie attached to the mucous membrane of the small intestine as in the case of E. granulosus. 2. The eggs are indistinguishable from those of E. granulosus. They are passed in the faeces of the final host, either free or in the gravid segment, and are infective to small rodents.

3. The larval form, the alveolar hydatid cyst （泡球蚴）, is found in a number of small rodents, and in man. 4. Man becomes infected by eating raw fruit or vegetables contaminated by the faeces of infected final hosts, or by handling them.

5. The lesion of alveolar hydatid cyst like a slow-growing malignant tumour, with poorly defined margins and it may extend into blood vessels and become dispersed into distant parts of the body. Over 90% of these cysts occur in the liver.