introduction to tromatodes phylum platyhelminthes class trematoda order digenea
TRANSCRIPT
Introduction to tromatodesIntroduction to tromatodes
Phylum PlatyhelminthesClass TrematodaOrder Digenea
MorphologyMorphology
• Adult worm– Flattened (flatworm) and leaf like– Sucker: oral & ventral (fluke)– Body wall: musculo-tegumental sac– Parenchyma (structure between body wall and i
nternal organs): connective tissue fibers, cells and space between them
– Digestive tract: not intact
i.e. no anal opening, caecum– Reproductive system: hermaphrodite (monoeci
ous) exception of schistosome– Muscular system– Nervous system– Excretory system
• Egg
– Size divergent
– Ovoid
– Operculum (exception of that of schistosome)
– Content: ovum , vitelline cells, or miracidium
Egg of Clonorchis sinensis
Egg of Paragonimus westermani
Egg of Fasciolopsis buski
S. japonicum S. Mansoni S. haematobium
Schistosome egg
Features Reflecting Features Reflecting Adaptation to ParasitismAdaptation to Parasitism
• Organs of attachment highly developed
• Retardation of digestive system
• Highly developed reproductive system
Life CycleLife Cycle
• Complex • Alteration of generation
sexual generation and asexual generation alter in the life cycle of parasite
• Asexual multiplication in larval stage in snail host• Multiple hosts transfer and having reservoir hosts
in majority• Water environment is essential
Important SpeciesImportant Species
• Liver fluke: Clonorchis sinensis
• Intestinal fluke: Fasciolopsis buski
• Lung fluke: Paragonimous westermani
P. skrjabini
• Blood fluke: Schistosoma spp.
The Liver FlukeThe Liver Fluke肝吸虫肝吸虫
Clonorchis sinensisClonorchis sinensis中华支睾吸虫中华支睾吸虫
Introduction Introduction
• Parasite of biliary passage
• Cause “clonorchiasis”
• A common trematode in Far East
• First report
1874 oversea Chinese in India
MorphologyMorphology
• Adult worm
– Size & Shape
like the seed of sunflower
– Sucker: oral = ventral
– 2 dendritic testes lie in tandem to each other in t
he posterior region (clonorchis)
Adults of Clonorchis sinensis
Cross section of Clonorchis sinensis adult in the hepatic bile duct
• Egg
– Size: smallest
– Shape: just like sesame
– Color: yellowish brown
– Operculum distinct: shoulder, knob
– Content: miracidium
Clonorchis sinensis egg. These are small operculated eggs. Size 27 to 35 µm by 11 to 20 µm. The operculum, at the smaller end of the egg, is convex and rests on a visible "shoulder". At the opposite (larger, abopercular) end, a small knob or hooklike protrusion is often visible (as is the case here). The miracidium is visible inside the egg.
Egg of Clonorchis sinensis
Life cycle of Clonorchis sinensis
Life CycleLife Cycle
• A model pattern of trematode
• Main points
– Definitive host: human being
– Reservoir host: dog, cat, etc.
– Residing: hepatic bile duct
– Discharge of eggs with feces
– Hatching in the host small intestine
– 2 intermediate host
I: snails, such as Bithynia,Parafossarulus
II: freshwater fishes, such as Cyprinus
– 2 generation of asexual proliferation
– Infective stage: metacercaria in fish
– Infective route: oral consumption
PathogenesisPathogenesis
• Due to adult worm
• Mechanism
– Mechanical: sucker
– Chemical: excretions, secretions, metabolite
– Biological: nutrition deprivation
• Pathological process
– Inflammation Proliferation
ThickeningOcclusion
– Extensive involvementFibrosis of the liver
Clinical ManifestationsClinical Manifestations
• Acute stage: allergic reaction
• Chronic stage: functional impairment of liver (Cholangitis, Cholecystitis, Bile stone, Jaundice, etc)
• Advanced stage: portal cirrhosis & malignancy
Laboratory DiagnosisLaboratory Diagnosis
• Etiological
– Examination of egg in feces by sedimentation
method
– Duodenal aspiration
• Immunological
– ELISA to detect antiboby or antigen
EpidemiologyEpidemiology
• Distribution
– Far East
(China, South Korea, Japan, etc.)
– 24 provinces in China
(Guangdon: 5 million infected etc.)
Endemic FactorsEndemic Factors
• Source of infection: mainly wild carnivores
• I,II intermediate host in the same water-
field
• Mode of fish breeding
• Dinning habit & Customs
Principle of ControlPrinciple of Control
• Cure patients & carrier
• praziquantel:25mg/kg, tid, 2 days
• Control reservoir host
• Carry out scientific fish-breeding
• Hygienic educationnot eating raw or undercooked fishes
Paragonimus westermaniParagonimus westermani卫氏并殖吸虫卫氏并殖吸虫
Paragonimus skrjabiniParagonimus skrjabini(Paragonimus szechuanensis)(Paragonimus szechuanensis)
斯氏狸殖吸虫斯氏狸殖吸虫
The Lung FlukeThe Lung Fluke
• Genus paragonimus
• Zoonotic parasite (cause zoonosis)
• Animal infection> human infection
• 2 major species in China
IntroductionIntroduction
• Pathogen of lung disease
• Endemic hemoptysis
• Favorite lodging site: lung
• Ectopic site: brain, abdomen, muscle, etc.
MorphologyMorphology
• Adult worm
• Body thick (a half piece of a bean grain)
• Tegument: spinous
• Sucker: oral = ventral
• Parallel arrangement of reproductive organlobular testes (posterior)lobular ovary & uterus (anterior)
Cross section of lung containing adult Paragonimus westermani.
• Egg
– Median size, ovoid (water pot)
– Golden yellow
– Distinctive & wide operculum
– Contain 1 germ cell & several yolk cells
Egg of Paragonimus westermani.
Life cycle of Paragonimus westermani.
Crab or crayfish
Life cycleLife cycle
• Definitive host: human being
• Reservoir host: carnivorous animals
• Habitation: lung & ectopic site
• Intermediate host:I: Melania snailsII: stream crabs, crayfish
• Infective stage: metacercaria
• Infective mode: oral route, may via paratenic host (swine)
• Migration & Preadult wondering
• Ectopic parasitism: cerebral, abdominal,etc.
• Eggs discharged with sputum & feces
• 3 generation of asexual multiplication
PathogenesisPathogenesis
• Stage take responsibility: adult & preadult
• Pathological processes
– Abscess stage( 脓肿期 )
– Cystic stage( 囊肿期 )
– Scar formation stage( 纤维疤痕期 )
• 4 clinical types– Thoracic (pulmonary type):chest pain, coughin
g, blood-tinged sputum(hemoptysis)– Abdominal (hepatic type):hepatomegaly– Cranial type: dizzy, headache, epilepsy– Musculocutaneous type: migratable subskin no
dule
Laboratory diagnosisLaboratory diagnosis
• Disease history + physical examination
• Etiological diagnosiseggs in sputum or feces by sedimentation
• Immunological diagnosisfor ectopic infections
EpidemiologyEpidemiology
• Globalmain continent except Europe
• China 23 provinces
Paragonimus westermani infection occurs in Asia (especially in China (Taiwan), Corea, India, Japan, Laos, Philippines, Sri Lanka, Thailand, Viet-Nam), Central-West Africa, South America (Ecuador, Peru Venezuela).
Principle of controlPrinciple of control
• Treat patient: praziquantel
• Hygienic education
• Social construction, economic refinement
The Ginger FlukeThe Ginger Fluke姜片虫姜片虫
Fasciolopsis buskiFasciolopsis buski布氏姜片吸虫布氏姜片吸虫
Intestinal flukeIntestinal fluke肠道吸虫肠道吸虫
MorphologyMorphology
• Adult worm
– Like a ginger piece
– Big muscular trematode
– Have strong suckers , ventral >> oral
Adult fluke of Fasciolopsis buski The adult flukes range in size: 20 to 75 mm by 8 to 20 mm
Fasciolopsis buskii adult worm
• Egg
– Biggest
– Ovoid
– Minute operculum
– Yellowish
– Germ cell inclusions
F.buski eggs are released in feces unembryonated. The operculated eggs are oval, brown and measure 130-150 by 78-100 um
Life cycle of Fascilopsis buski
Life CycleLife Cycle
• Definitive host: human being
• Reservoir host: swine, etc.
• Intermediate host: Planorbis snails
• Aquatic plant vectors: caltrops, water chestnut, etc.
• Habitation: small intestine
• Infective stage: metacercaria
• Infective route: oral
• Developmental stages: as Paragonimus
• 3 generation of asexual proliferation
Pathogenesis FactorsPathogenesis Factors
• Traumatic (suckers)
• Obstructive (due large size)
• Toxic (excretion, secretion, metabolite)
Clinical ManifestationClinical Manifestation
• Abdominal pain
• Acute intestinal obstruction
• Anemia
• Generalized edema
Laboratory DiagnosisLaboratory Diagnosis
• Examination of egg in feces by sedimentation method
EpidemiologyEpidemiology
• Aquatic plant raising districts
Fasciolopsis buski: is endemic in China (Taiwan), South-East Asia,
Malaysia and India.
Principle of ControlPrinciple of Control
• Drug for treatment: praziquantel
• Water & nightsoil control; Scientific swine raising
• Hygienic education
IntroductionIntroduction
• 6 species of human schistosomes– Schistosoma japonicum– S. mansoni– S. haematobium– S. intercalatum– S. mekongi– S. malayi
Schistosoma japonicumSchistosoma japonicum
日本血吸虫
Distribution and Epidemic SituationDistribution and Epidemic Situation
• Worldwide– 200 million of population infected in 74
countries(S.m. 55; S.h. 55; S.j. 4; S.i. 10; S.me. 2; S.ma. 1)
• China– 11 million in 12 provinces 0.7 million in 8
provinces
50 years
Before control After control (1996)
Regional distribution of S. japonicum infection in China
Morphology Morphology
• Difference from other trematodes
– Dioecious adults
– Non-opeculate egg
– Bifurcated (forked) cercaria invades the final ho
st by skin
– Adults parasitize blood vessels
• Adult
– Male (15 mm length) < female (22 mm)
– Oral sucker < ventral sucker
– 2 paralleled guts form a blind caecum in the pos
terior ends
– 7 testes in male and single ovary with a tubule
uterus in female
– Gynecophoric canal (male) in which female rep
ose
• Egg
– Ovoid and non-opeculate
– 74~106 m × 55~80 m
– Contains one miracidium
– Bear a minute lateral knob.
• Miracidium
• Cercaria
S. japonicum S. Mansoni S. haematobium
Schistosome egg
Schistosome miracidium
Schistosome cercaria
Life CycleLife CycleEggs discharged fresh water (hatch) miracidia pe
netrate oncomelania(I.H.)mother sporocysts (multiplica
tion) daughter sporocysts (multiplication) cercariae
(infective form) skin penetration of D.H. schistosomul
um right heart lungs left heart
systemic circulation portal system pairing and sexu
al maturation mesenteric veins lay eggs eggs develo
p and live in tissue for 21 days( 23% in liver tissue, 60% in int
estinal tissue, 17% discharged)
Cercarial dermatisis due to avian schistosome
Main Points of Life CycleMain Points of Life Cycle
• Residing site: mesenteric vein
• I.H.(Only one): Oncomelania hupensis
• No metacercaria and redia stage
• Two generation of sporocyst
• Infective stage: cercaria
• Route of infection: skin penetration
Adult of Schistosome in mesenteric veins of hamster
Onchomelania hupensis
Skin penetration of cercaria first
appearance of eggs: 30~35 days
Life spans in human: 4~5 years, longest: 35
years
• Tissue egg
– The egg which can develop and live in tissue
• Significance of tissue egg
– Major pathogenic stage, inflammation and
granuloma around the egg
– Diagnosis and evaluation of therapeutic
efficacy
ImmunityImmunity
• Concomitant immunity
– Host carrying an initial infection of adult schist
osomes shows the protection to a cercarial chall
enge infection ( 攻击性感染) and this protecti
ve immunity will disappear with eradication of
schistosomes in the host
• Immuno-evasion: It’s an ability by which the schistosome adult can evade the host immune response. The possible mechanism of evasion.– Acquire host antigen on it surface
– Host-like antigen produced by parasite
– Changing of tegument very quickly
– Parasite may inactivate or down-regulate immune effectors
PathogenesisPathogenesis
Schistosomiasis at each stage of the life cycle in human body
• Cercaria (skin-penetration)– Dermatitis
• Schistosomula (migration)– Larva migrans
• Adult: (immunocomplex)– Immuno-nephropathy
• Tissue egg: principal pathogenic stage
Miracidium within eggSEASensitization of T Cell
Th1IL-2, INF-, TNF activate macrophage, induce cell-mediated immunity
Th2IL-4, IL-5 stimulate IgE production or eosinophilia
inflammation and granuloma fibrosis portal hypertension
intestinal polyp
Clinical FormClinical Form
• Acute schistosomiasis– Fever, diarrhea, abdominal pain, enlargement of liver o
r spleen
• Chronic schistosomiasis– asymptomatic or diarrhea, abdominal pain, enlargement
of liver or spleen
• Advanced schistosomiasis– Ascites; splenomegaly;collateral circulation; dwarfism;
– Ectopic lesion: encephalitis; focal epilepsy
Advanced schistosomiasis patient with portal hypertension and ascites
A patient with S. j has marked ascites, splenomegaly,umbilical hernia and distended superficial abdominal veins.
DiagnosisDiagnosis
• Parasitological diagnosis (etiological, definitive diagnosis)– Demonstrating eggs by stool examination– Stool examination after concentration
(sedimentation)– *Miracidium-hatching from eggs– Rectal biopsy — eggs-demonstration
Miracidium-hatching from eggsMiracidium-hatching from eggs
Necessity: tissue ova;
low egg burden due to mass treatment
Possibility:• Hatch quickly (T:25; limpid water; free of
Cl2;light; pH=6.8-7.8)
• Three tropism:limpidity, phototrophic, ascendancy• Swimming in a zigzag way
• Immunodiagnosis (indirect diagnosis)
– Detection of antibodies in serum, urine, saliva b
y ELISA, but is impossible to distinguish curre
nt infection from past infection.
– Detection of antigens (circulation anodic and ca
thodic antigen)
• Combined diagnosis: including
epidemiological antecedent, symptoms and
signs, parasitological and immunological
examination.
TreatmentTreatment
Praziquantel 60 mg/kg divided in 3 doses.
Factors of Transmission and Factors of Transmission and PreventionPrevention
• Factors– Source of infection: patients and reservoir host– Intermediate host: Oncomelania– Contact with cercaria-infected water
• Preventive measures– Detection and treatment of patients and reservoir h
ost
– Elimination or control of oncomelania
– Protection of susceptible population and avoidance of contact with cercaria-infected water
– Prevention of water contamination by human night soil
Distinguishing of 3 major Distinguishing of 3 major schistosomesschistosomes
(see page 54, Table 3-1)