Trematodes: Blood Flukes Flashcards
1
Q
5 Species of medically important Schistosoma
A
S. japonicum S. mansoni S. haematobium S. mekongi S. intercalatum
2
Q
Predominant Schistosoma in the PH
A
S. japonicum
3
Q
Common name of S. japonicum
A
Oriental blood fluke
4
Q
Disease caused by S. japonicum
A
Schistosomiasis japonica
5
Q
S. japonicum is endemic in?
A
China
PH
Indonesia
6
Q
When was S. japonicum eliminated in Japan (the last case reported?)
A
1977
7
Q
History
S. japonicum was identified in a?
A
Female corpse fom Western Han Dynasty
2000 years ago
8
Q
The disease was first described by? When?
A
Fuji
1847
9
Q
When was the Adult S. japonicum descibed? By who?
A
Katsurada
1904
10
Q
First case in China
A
1905
Logan
11
Q
First case in the PH
A
1906
Wooley
12
Q
Intermediate host of S. japonicum
A
Snails of the species Oncomelania
13
Q
Phenotypic variation of S japonicum strains
A
Minor morphologic char. Infectivity to Oncomelania snails Periodicity of cercarial emergence Ability to develop in diff def hosts Growth rate Egg prodn Pre-patent period Pathogenicity Immunogenicity
14
Q
Compare chinese from PH strains
A
- Injection of irradiated cercariae of the Chinese strain confers resistance to the homologous strain but not to the PH strain
- Mouse pathogenicity of the Chinese strain is lesser than that of the PH strain
15
Q
S. japonicum in the PH found in?
A
Mindoro, Leyte, Sorsogon, Mindanao
16
Q
Most research in the PH of the S japonicum was focused in the?
A
Leyte strain
17
Q
Life cycle of Schistosoma
A
Recite
18
Q
Dx stage of Schis?
A
Embryonated egg
19
Q
Hours it takes for the embrynated egg to hatch in a fresh water?
A
2 to 4 H
20
Q
Embryon. egg hatches to become?
A
Miracidia
21
Q
Free swimming cilliated stage
A
Miracidia
22
Q
Intermediate host of S. japonicum
A
Oncomelania hupensis quadrasi
23
Q
Miracidia inside the snail transforms into?
A
Sporocyst
24
Q
Sporocyst transforms into?
A
Cercaria
25
Time it takes for sporocyst to become cercariae
60 to 70 days
26
Infective stage to the definitive host
Cercariae
27
Cercaria loses its tail to become?
Schistosomula
28
Schistosomula enters
Subcutaneous veins and superficial lymphatic vessels into the lungs
29
Lungs to portal vein, how?
Intravascularly
| Pleural cavity to diaphragm to liver
30
Where does the schistosomula mature
Portal vein
31
Which is larger? F or M
F
32
Female schistosome occupies what of the male?
Gynecophoric canal
33
Female lays how many eggs?
500 to 2000 eggs/day
34
Time it takes for the immature eggs to become mature and embryonated
10 to 12 days
35
Time deposit eggs after the penetration
24th to 27th day after penetration
36
Definitive hosts of S japonicum
Humans, cats, dogs, pigs, cows and carabaos
37
Sylvian reservoirs of S japonicum
Monkeys and rodents
38
Permissive hosts of S japonicum
Humans, rabbits and mice
39
A large series of experimental crosses was done where and when?
Leyte
| 1954 to 1957
40
Shape of japonicum eggs
Ovoid, round, pear-shaped
41
Color of japonicum egg
Pale yellow
42
Diameter of japonicum egg
Longer: 46 to 110 um
Shorter: 37 to 90 um
43
Ideal temp and pH for the eggs to hatch
25 to 31 degrees
Slightly alkaline
Sufficient oxygen
44
Eggs will not hatch if salinity is greater than?
0.7%
45
Miracidia remain infective for?
8 to 12 H
46
How does miracidia penetrate snail Oncomelania hupensis quadrasi?
- movement
| - lytic action of the cephalic gland secretions
47
Describe what happens to miracidia after penetration
Complete penetration- loses ciliated portion
Several days- transforms into primary or mother sporocyst near the point of entry
After 96 hours- become elongated sac-filled with germinal cells
At 8th day- germ cells bud off the epithelial lining and transforms into daughter sporocyst
48
In Mindoro, how many percent of the infected Oncomelania hupensis quadrasi only shed cercariae
6 to 10%
49
Has a body and a forked tail
Cercaria
50
Size of the cercaria
Body: 100-500 x 40-60 um
Tail trunk: 140-150 x 20-35 um
Fork: 50- 70 um
51
What suckers does the cercaria has?
```
Oral sucker (occupies the anterior end of the body)
Ventral sucker
```
52
Shedding of cercariae from the time miracidia penetration may be observed as early as?
42nd day
53
Average day of cercariae shedding after miracidial upon miracidial penetration?
62 days
54
Total number of cercariae shed in a singly infected snail?
230
55
Total number of cercariae shed in a multiply infected snail?
280
56
In average, how many cercariae is shed every day?
2 per day
57
Oncomelania hupensis quadrasi can withstand drying for how many days?
7 to 10 days
58
Oncomelania hupensis quadrasi is taken out from the aquaterraria for ———— before crushing
2-4 days
59
Two factors that explains why cercariae are shed at night?
1. Negative effects of exposure to sunlight
| 2. Oncomelania is more active and mobile at night
60
After release, cercaria can survive for up to?
24 H
61
Temp preference of japonicum
35 +/- 3 degrees
62
Penetration of cercariae is stimulated by?
Skin lipids
63
Chemicals that repel cercariae
Dimethylate and niclosamide
64
Upon penetration of the cercaria, what happens next?
Loses tail
| Cercarial tegument is replaced by 5 to 7-layered membran
65
In lab, how can a cercaria be transformed into a schistosomule?
1. Repeated passage thru a small bore needle syringe
2. Passage thru isolated skin
3. Application on a surface with skin lipids or crude egg lecithin
66
Schostosomule can be found on the pleural cavity at what day?
2nd day of infxn
67
Schistosomule can be found in the parenchyma of the diaphragm on day?
4th day
68
On what day does schistosomule found in the liver parenchyma?
6th day
69
Correlation b/n # of lung petechiae vs numb of schistosomes recovered
Lung petechiae on the 4th to 6th day: number of recovered schistosomes at day 30 from portal system by perfusion
70
As compared to other flukes, Schistosoma species are?
Dioecious
71
Suckers of adults
Large suckers, ventral sucker, gonophore
72
Describe male schistosome
Shorter but sturdier
12 to 20 mm x .4-.5mm
Testes are arranged in one row above the ventral suckers
73
Describe the female schistosomes
Longer and slender
15-26mm x 0.3mm
Single pyramidal ovary located midline
74
Schistosomes can live up to?
30 years
75
Average life span of schistosomes
3-8 years
76
Digestive system of schistosomes
Incomplete
77
Excretory systme of schistosomes
Made up of flame cells
78
Internal structures of schistosomes are covered with
Longitudinal and circular muscles
79
Ingests red cells and posses
Protease (hemoglobinase) that breaks down globin and hgb
80
Cercarial penetration accompanied by dermatitis with pruritus and localized reaction
Swimmer’s itch
81
ERAMMEFA
Katayama Syndrome/ Katayama Fever/ Snail Fever
82
When does Katayama fever seen
2 to 12 weeks following cercarial penetration
83
Migration thru pulmonary circulation may cause
Coughing and wheezing
84
Aberrant migration of maturing schistosomes may occlude the circulation of the brain casuing
Seizures, paresthesias, transient ischemic attacks, stroke
85
Main pathology of schistosomiasis
Granulomatous reaction to egg deposited in the liver and other organs
86
Determines the severity of infection
Initial quantum of cercariae that infect the host and mature to lay eggs
87
Eggs deposited in what organs?
Liver
Lung
Intestines
Brain
88
3 stages of schistosomiasis clinical course
1. Incubation period
2. Period of early egg deposition and extrusion
3. Period of tissue proliferation
89
Became the subjects for the study of early manifestations of schistosomiasis
American soldiers who landed in Leyte in 1944
90
Pre-patent period from 337 cases
42 to 52 days
91
T/F
| In chronic stage, colonic schistosomiasis is usually ASYMPTOMATIC
Chrue
92
Most serious consequence of chronic schistosomiasis
Hepatosplenic dseas
93
Hepatsplenic dseas manifest as
Hepatosplenomegaly
Portal hyoertension
Ascites
Collateral circulation causing esophageal and gastric varices
94
Pesigan
```
2540 cases
1950-1951 DOH
31%: mild hepatsplenic dseas
9.1%: definite signs of ascites
1.4%: severe portal hypertension with prominent ascites
```
95
Cinco
14%: hematemesis and melena
96
Jongco and Flaminiano
1961
| Pulmonary schistosomiasisis the most common cause of Cor Pulmonale in Fil Children
97
Cerebral schistosomiasis
1.7 to 4.3%
| 1945 American soldiers in Leyte, 2% with CNS involvement
98
Acute cases of CNS schistosmiasis
```
Meningiencephalitis
Headache
Confusions
Lethargy
Coma
```
99
Chronic cases of CNS schistosomiasis
Increased ICP
| TUMOR
100
Most specific examination of eggs since these directly visualize the parasite
Microscopic examination
101
Microscopic techniques include?
Stool exam
| Rectal imprint
102
Has sufficient sensitivity for heavy and moderate infections but nit adequate for very light infxn (less than 10 eggs per gram)
Merthiolate-Iodine-Formalin Concn Technique
103
Concn technique suitable for field studies
MIFC
104
Fecal samples mixed w this soln can be kept indefinitely
| Preserved protozoans
Merthiolate-Formalin soln
105
Preferred egg count egg counting tech and used for egg qunatification
Kato-Katz Tech
106
Most commonly used stool exam technique for evaluating epidemiology, effect of control measures, and drug trials
Kato-Katz techn
107
Kato-Katz Tech can be kept for?
2 weeks
108
Specimens with less than 20 eggs per gram requires
At least 3Kato-Katz prep to achieve a sensitivity of 92%
109
Most invasive
Rectal snips and imprint
110
T/F
| Rectal snips/ imprint does not distinguish b/n treated or untreated infxn
Chrue
111
Locally evaluated immunodiagnostic tests
1. Intradermal test for immediate cutaneous hyoersensitivity
2. Indirect Hemagllutination
3. COPT
4. ELISA
112
Intradermal tests makes use of
Adult worm extract
113
Indirect Hemagglutination test makes use of
Adult worm and egg antigen
114
ELISA makes use of
Soluble antigen of adult worm and egg
115
Most specific antigen from the multicenter evaluation of S japonicum diagnostics
Crude egg antigen
116
Highly sensitive but not specific
Intradermal test
117
Highly sensitive and requires specialized reagents and training but can be performed w/ minimal equipment
HAT
118
Among the most sensitive
| Need lab equipment and trained personnel
ELISA
119
Harness ELISA for point of care and field use
Validated extensively in China
Best suited for elimination programs
Lateral flow assays
120
T/F
| Adult worm ag were found to be better than egg ag for detecting low level infxns (less than 100 eggs/gram)
T
121
COPT positive result
Formation of blebs or septate precipitates attached to one or mor points on the egg surface
122
Method of choice for the definitive dx of schistosomiasis in the PH
COPT
123
COPT takes more than —- to become negative
2 years
124
Standardized egg preps for COPT is obtained from?
50 - 60 day old S japonicum infxnx of rabbits
125
Barrio San Antonio, Basey, Samar
COPT and MIFC
COPT: 70% +
Stool exam: 40% only
126
Drugs used for schistosomiasis
Praziquantel
127
Heterocyclic prazinoisoquinoline cmp
Praziquantel
128
Active substance of praziquantel is?
Hygroscopic, colorless, almost odorless, crystalline powder
Melts at 136- 140 deg C
Highly soluble to chloroform and dimethyl-sulfoxide
129
Experiment of praziquantel toxicity with rats and dogs
Rats: 1mg/kg for 4 weeks
Dogs: 180 mg/kg for 13 weeks
Both without organ damage and well tolerated
130
Used for pre-exposure prophylaxis
Artemisinins including Artemether
131
Epidem of schistosomiasis
```
12 regions
28 provinces
190 municipalities
15 cities
2,222 brgys
```
Added
Gonzaga, Cagayan 2004
Calatrava, Negros Oriental 2006
132
Population at risk
6.8 million
133
Highest prevalence of infxn isin children
5 - 15 y/o
134
More useful epidemiologic indices
1. Prevalence
2. Incidence
3. Worm burden
135
Place with highes prevalence
Agusan del Sur. 3.95%
136
Oncomelania hupensis quadrasi attain sexual maturity?
If size reaches 3.5 mm
137
O. h. quadrasi lays egg
2 eggs per 5 days for 1 month
138
2 general strategies for snail control
Focal
| Area-wide
