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dlmedu ryx
Trematodes
Department of ParasitologyDalian Medical University
Ren Yixin
dlmedu ryx
8 lessons
6 lessonsTrematodes
2 lessonsCestodes
areview
Clonorchis sinensisParagonimus westermani
Fasciolopsis buskiSchistosoma japonicum
Teania soliumTeania saginata
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• Trematode • Cestode
suckers
ribbonlike
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common names
• Clonorchis sinensis: Chinese liver fluke• Paragonimus westermani: lung fluke• Fasciolopsis buski: intestine fluke• Schistosoma japonicum: blood fluke• Teania solium: pork tapeworm• Teania saginata: beef tapeworm
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Common characters of Trematodes
Morphous Life cycle
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Introduction to Trematoda
digenetic trematodes
Leaf-shaped or elongate flat body, resistant cuticle, bilaterally symmetrical without body cavity 2 suckers oral sucker ventral sucker
Monoecism male and female reproductive
system are in the same body
attachmentlocomotion
Morphology of Adult Schistosoma
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Trematode Digestive Tract
Simple mouth
pharynx
esophagus
intestine
Anus absent
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Male reproductive system
two testis
vas efferens 输出管 vas deferens 输精管
Seminal vesicle 储精囊
prostatic gland 前列腺
ejaculatory duct 射精管
cirrus 阴茎
cirrus pouch 阴茎袋
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Female reproductive system
Ovary 卵巢 Oviduct 输卵管Ootype 卵模Mehlis gland 梅氏腺Seminal receptacle 受精囊Laurer’s canal 劳氏管Vitellaria 卵黄腺Vitelline duct 卵黄管Vitelline reservior 卵黄囊 ( vitelline glands )Uterus 子宫
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Eggs
liver fluke's egglung fluke's egg
intestine fluke's egg blood fluke's egg
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Life cycle:
several development stages of a fluke
Adult eggs miracidium sporocyst
Adolescaria metacercaria cercaria redia
童虫 囊蚴
毛蚴 胞蚴
雷蚴
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cercariasporocyst
metacercaria
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One or two intermediate hosts are required :
First intermediate host is snail
second intermediate host is fresh water fish (clonorchis sinensis)
second intermediate host is crab, crayfish (Paragonimus)
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dlmedu ryx
*Characters of life cycle*
• The trematodes are biohelminths, they need 1 or 2 intermediate hosts, the first intermediate host is mainly fresh water snail.
• Asexual reproduction occurs in the larval stages, sexual reproduction occurs in the adult stage.
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Clonorchis sinensis 华支睾吸虫
Chinese liver fluke
Disease is Clonorchiasis
In China: more than 1.2×107
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The Chinese liver fluke, the The Chinese liver fluke, the trematode trematode Clonorchis Clonorchis sinensissinensis
discovered in the bile discovered in the bile passage of a Chinese at passage of a Chinese at autopsy in Calcutta, India in autopsy in Calcutta, India in 1875 firstly1875 firstly
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dlmedu ryx
Morphology
Life cycle
Pathogenesis & clinical manifestation
Diagnosis
Epidemiology
Prevention & treatment
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Morphology of Clonorchis sinensis
Adult : elongate, narrow, 10-25 mm long,3-5mm wide.
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oral sucker pharynx
ceca
Acetabulumventral sucker
genital pore
Seminal receptacle
uterus
ovary
Testis
esophagus
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Morphology of Clonorchis sinensis
Egg: the smallest
29 ×17µm
operculum
Tiny knob
eggshell
broad rim ("sh
oulder")
miracidium
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dlmedu ryx
Life cycle of C.sinensis
egg miracidium sporocyst redia
cercariametacercarialarva
redia cercaria metacercaria
adult
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Life cycles
parafossarulus
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cercaria
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metacercariae
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First intermediate hosts
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Second intermediate host
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• The patholgical consequences of C.sinensis occur mainly in intra-liver secondary bile ducts. The ultimate effect depends on the intensity and duration of the infection.
• burdens usually small (20-200)
Pathogenesis
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Pathogenesis
Worm in bile ducts
Mechanical irritation
Toxic substances
Erosion of epithelium
Proliferation in biliary epithelium
Bile retention, fibrosis,cancer
Left lobe is mostly involved
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Two adult worms (arrow) in the ductal lumen
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Pathogenesis
extreme thickening of the bile duct (epithelium proliferate).
fibrosis
* Cholangitis
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White areas show cirrhosis in infected liver
* Cirrhosis of liver
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Other symptoms:
Jaundice
upper abdominal distress
diarrhea
hepatomegaly
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Epidemiology
• source of infection
• route of transmission
• susceptible population
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•Source of C.sinensis infection:
Infected human
Infected livestock
Infected wild animals
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Epidemiology
Fish ponds where both snails and fish are present.
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Epidemiology
raw fish is considered a delicacy
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Epidemiology
Human is infected by eating
raw, undercooked, frozen,
dried, salted, smoked fish.
Metacercariae in fish can
withstand salting, smoking,
frozen and drying.
second intermediate hosts
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Epidemiology
Definitive host: Human
Reservoir hosts: dogs, cats and rats
First and second intermediate host
Way of acquiring: eating raw fish with metacercariae
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Diagnosis
small with operculum
at constricted end
broad rim
tiny knob
卵 盖
Detection of the characteristic eggs in stool or in bile or fluid obtained from duodenum
Associate the history of eating raw fish
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Prevention: safe consumption of infective fish proper sanitation control of human feces. control of the snail and the
reservoir hosts
The drug of choice is praziquantel 吡喹酮
75 mg/kg, divided 3 doses one day, 2-3days
Treatment of Clonorchis sinensis