TREMATODES (DIOECIOUS FLUKES) Flashcards
- Oriental blood fluke
Schistosoma japonicum
- Visceral blood fluke
Schistosoma japonicum
- Vesical blood fluke
Schistosoma haematobium
- Bladder fluke
Schistosoma haematobium
Manson’s blood fluke
Schistosoma mansoni
Superior mesenteric veins
Schistosoma japonicum
Veins of the urinary bladder
Schistosoma haematobium
Inferior mesenteric veins
Schistosoma mansoni
China, Japan, Indonesia, Thailand, Cambodia, Philippines
Schistosoma japonicum
Intermediate hosts: Snails
- Oncomelania quadrasi (Philippines)
- Oncomelania nocophara (Japan)
- Oncomelania formosana (Taiwan)
Schistosoma japonicum
Intermediate hosts: Snails
- Biomphalaria (Africa)
- Bulimus (Middle east)
Schistosoma haematobium
Intermediate hosts:
- Biomphalaria (Africa)
- Tropicorbis (South America)
- Austrolarbis
Schistosoma mansoni
Ova/Eggs ➢ Measuring about 50-85 um by 38-60 um;
Schistosoma japonicum
Ova/Eggs ➢ Oval to sub-spherical with minute lateral spines/knob
Schistosoma japonicum
✓ Females ➢ More delicate than males
Schistosoma japonicum
✓ Females ➢ Longer and slender
Schistosoma japonicum
✓ Females ➢ With pyramid ovary located at the center of the body (containing 50-100 eggs)
Schistosoma japonicum
✓ Males ➢ shorter but sturdier; measuring about 12-20 mm by 0.4-0.5 mm
Schistosoma japonicum
✓ Males ➢ with 7 ovoidal testes arranged in single row behind acetabulum
Schistosoma japonicum
✓ Males ➢ union of ceca and testes is posterior to the middle half of the body
Schistosoma japonicum
Ova/Eggs ➢ Ellipsoidal with prominent terminal spines measuring about 110-170 um by 38-70 um
Schistosoma haematobium
Adult ➢ The ovary is located at the posterior to middle of the body containing 20-30 eggs
Schistosoma haematobium
Ova/Eggs ➢ Ellipsoidal with prominent lateral spines
Schistosoma mansoni
Ova/Eggs ➢ Measures 112-182 um by 40-75 um
Schistosoma mansoni
Ova/Eggs ➢ Appear in the feces 30-40 days after infection
Schistosoma mansoni
✓ Females➢ Considered as the smallest schistosome
Schistosoma mansoni
✓ Females ➢ Ovary is at the anterior to the middle half of the body containing 1-4 eggs
Schistosoma mansoni
✓ Males ➢ Union of ceca is at the middle half of the body containing 8-9 testes
Schistosoma mansoni
- Katayama disease
Schistosoma japonicum
- Oriental schistosomiasis/Visceral schistosomiasis
Schistosoma japonicum
- Vesical/Urinary schistosomiasis
Schistosoma haematobium
- Schistosoma hematuria
Schistosoma haematobium
- Intestinal Bilharziasis
Schistosoma mansoni
- Schistosomal dysentery
Schistosoma mansoni
There are three (3) progressive stages in the pathologic processes of Schistosomiasis:
- Pre-patent/Developmental stage
- Acute stage
- Chronic stage
➢ Starts from the penetration of the skin to the arrival of the mature worm to the venules of the intestines or urinary bladder where female adults are ready to oviposit
- Pre-patent/Developmental stage
✓ Negligible to mild cutaneous lesions at the side of cervical entry
- Pre-patent/Developmental stage
✓ Tissue reactions to the immature worms inside and outside the blood vessels
- Pre-patent/Developmental stage
✓ Some associated toxic and allergic reactions
- Pre-patent/Developmental stage
:➢ There is active egg deposition and extrusion
- Acute stage
➢ Symptoms include: Loss of weight and relapse of pain
- Acute stage
➢ Stable egg output and tissue proliferation
- Chronic stage
➢ Invasion of the tissues by the migrating larva
- Chronic stage
✓ Petechial hemorrhage
- Chronic stage
✓ Small foci of eosinophilic and neutrophilic infiltration in the lungs with cough and hemoptysis
- Chronic stage
✓ Acute inflammation reactions in the liver with fever and urticaria
- Chronic stage
- Demonstration of eggs in stool sample is diagnostic of Schistosomiasis
- Concentration techniques – useful in chronic and light infections
- Liver biopsy/Proctoscopic aspiration
➢ Demonstration of eggs in feces
- Diagnosis of S. japonicum and S. mansoni
➢ Rectal biopsy
- Diagnosis of S. japonicum and S. mansoni
➢ Demonstration of eggs in urine or recovery of eggs through bladder biopsy
- Diagnosis of Urinary schistosomiasis
➢ Accompanied with dysuria and hematuria
- Diagnosis of Urinary schistosomiasis
- Immunodiagnostic Tests:
a. COPT (Circumoval Precipitin Test)
b. ELISA – highly sensitive test
➢ Principle: it is based on patient serum precipitation with lyophilized eggs identified under microscope
➢ Uses lyophilized eggs to detect antibodies in patient serum
➢ Gold standard test for diagnosis of Schistosomiasis
➢ Method of choice and is routinely used in the Philippines as diagnostic test for schistosomiasis
➢ DISADVANTAGE: Cross-reactivity with other helminths (affects specificity)
➢ Procedure:
a. One drop (?) of the suspension containing larvae, eggs, or immature adults are put into the well of a slide and 3 drops (?) of serum is added
b. A [?] is placed over the well
c. Incubated at [?]
d. After incubation, the slide is examined under the [?]
e. Positive result: appearance of [?] attached to the worms or eggs
0.025 mL; 0.075 mL
cover slip
34°C for 24 hours
microscope
precipitates/bleb formation
Prevention and Control
✓ Snail control
✓ Sanitary disposal of human excreta
✓ Treatment of infected individual
Treatment
✓ Praziquantel
✓ Oxamniquine
✓ Metrifonate
✓ Niridazole
The schistosomes of man are similar in their basic [?]and in their pathologic effects on mammalian host tissues, yet they differ in [?] of the adults, the [?] of their eggs and larvae, in the groups of snails that they utilize as an [?], and in [?].
life cycles
morphology
shape
intermediate host
host susceptibility
The most significant species of Schistosoma that causes disease to humans are
S. japonicum, S. mansoni, and S. haematobium
