Schistosoma Flashcards

1
Q

what is the source of cercarie of schisto

A

transdermal from freshwater

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2
Q

what is the most important human helminth infection

A

schistosomiasis

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3
Q

how many people infected with schisto in africa

A

200 million

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4
Q

how many people die due to schisto in sub saharan africa per yeat

A

200 000

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5
Q

which parasite was found in 3100 bc mummies

A

schisto

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6
Q

where does schisto mature un the definitive host

A

the blood vascular system

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7
Q

schisto is associated with what

A

renal, bladder dysfunction, liver or intestinal disease

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8
Q

wha are the intestinal schisto parasites

A

-mansoni
-japonicum
-mekongi
-guineesis, intercalatum

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9
Q

where is mansoni found

A

middle east africa
caribbean
brazil
venezuela
suriname

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10
Q

where is japonicum found

A

china
indonesia
philipines

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11
Q

where is mekongi found

A

cambodia
lao

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12
Q

where is guineensis and intercalatum found

A

rain forest of central africa

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13
Q

which schisto is urogenital

A

haematobium

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14
Q

where is haematobium found

A

middle east africa
corsica aka france

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15
Q

which schisto is the most widely distributed and is endemic in its areas

A

mansoni

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16
Q

construction of the egyptian dam in the 60s led to what

A

the virual elimination of haematobium from the nile delta but has brought the establishment of mansoni in upper egypt

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17
Q

construction of diama dam in senegal river led to what

A

the introduction of schisto into mauritania and senegal

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18
Q

construction of akosombo dam in ghana led to what

A

the introduction if shisto into lower volta river

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19
Q

the movement of refugees and the displacement of populations resulted to what

A

the intro of schisto in somalia and djibouti

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20
Q

what are the 3 major species of schisto

A

mansoni
haematobium
japonicum

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21
Q

true or false: in schisto, females are bigger than males

A

so true

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22
Q

what are the lil features of male schisto

A

-oral and ventral sucker
-gynocophoric channel for female to get in
-sturdy body and tuberculated tegument

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23
Q

what is the ;enght of male schisto haematobium

A

10-15 mm

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24
Q

what is the lenght of mansoni

A

6-12 mm fp male

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25
Q

what is lenght of male japonicum

A

12-20 mm

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26
Q

what is the intermediate host of schisto

A

snail

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27
Q

what is the snail for haematobium

A

bulinus

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28
Q

what is the snail for mansoni

A

biomphalaria

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29
Q

what is the snail for japonicum

A

oncomelaniawhere

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30
Q

are usually the cercariae in

A

fresh water

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31
Q

how do schisto infect people

A

they penetrate the skin

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32
Q

what is life cycle of schisto starting from penetration

A

-penetration of the skin
-cercariae become schistosomula
-larvae migrate first to the lungs through venous circulation
-larvae migrate to the heart and into circulation
-larvae mature in liver
-worms mature and pair off
-worms migrate to mesenteric vessels of bowel or bladder where females lay eggs
-eggs excreted in feces or urine
-eggs get into snail
-miracidia develop into sporocyst and produce cercariae

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33
Q

how long to schisto take to develop into mature miracidium

A

8-10 days

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34
Q

what is the color of schisto eggs and what is their special characteristiv

A

they are yellowish brown and elongate with a spine

35
Q

what is the size of the egg haematobium

A

140u

36
Q

what is the size of the egg mansoni

A

140u

37
Q

what is the size of the egg japonicum

A

85u

38
Q

what is the life expentancy of shisto in tissues

A

21 days

39
Q

what is the lenght of the swimming ciliated miracidium and how long does it live for

A

100-200u and lives 8-12 hrs

40
Q

miracidium male or female gives rise to what and how long do they live for

A

-give rise to cercaria of the same sex
-live up to 3-4 days

41
Q

penetration of schisto is triggered by what

A

chemical and theremal cues

42
Q

cercaria penetration is accompanied by what

A

-the transformation of the free living cercaria to a parasitic larval schistocomulum

43
Q

Schistosomules enter the capillary bed or the lymphatic
system, migrating to where?

A

the right side of the heart and then entering the lungs

44
Q

juveniles of schisto feed on what and then what happens

A

erythrocyte and grow rapidely
-after 10 days the schistosomules move through the pulmonary vein to the left side of the heart and then into systemic circulation

45
Q

3 weeks after penetration, the worms of schisto will reach what

A

hepatic portal vein

46
Q

initial egg production begins when for schisto?

A

-4-7 weeks after infection

47
Q

s mansoni mature females produce how many eggs per day

A

100-300 eggs

48
Q

how long do adult schisto adults live

A

3-8 yrs

49
Q

what is the first clinical sign of shchisto

A

skin bumps

50
Q

what is a clinical sign of s mansoni

A

cercarial dermatitis

51
Q

what causes swimmers itch

A

avian schisto

52
Q

true or false: cercarian dermatitis is an igg mediated hypersensitivity response

A

false it is an ige response

53
Q

what is cercarial dermatitis characterized by

A

-maculopapular, pruritic rash that manifests within several hours of exposure to the contaminated water and may persist for days

54
Q

when is acute dermatitis

A

4-10 weeks after infection

55
Q

what is the name of the acute stage of the acute stage os schisto and what is it

A

katayama fever
-normally found in kids or adults with no previous exposure to the disease
-it is a response to the sudden high levels of antigen exposure
-is usually assocuated with the onset of egg deposition

56
Q

what are the clinical symptoms of acute schisto

A

-skin rashes
-asthmalike episodes
-daily fever
-malaise
-diarrhea
-swollen lymph nodes
-aching joints

57
Q

which is most common with katayama fever in terms of which schisto

A

japonicum

58
Q

in schisto: accumulation of eggs and fibrotic reactions leads to what

A

cirrhosis and portal hypertension
-ascites (fluid accumulation in the abdominal cavity) is common
-some eggs pass the liver, lodging in the lungs, brain and other organs

59
Q

in s haematonium, fibrosis of the bladder may lead to what?

A

ureteric obstruction and renal failure

60
Q

true or false: s mansoni can cause growth stunting

A

true due to chronic infection

61
Q

pathology of schisto is due to what

A

egg deposition in tissues and not adult worm

62
Q

-eggs become surrounded by granulomas and antigen leakage lead to what

A

delayed type hypersensitivity aka DTH reactions

63
Q

what is the granuloma

A

concentric layers of cells that together form the distinctive lesion

64
Q

what is the central focus of the granulomas of schisto

A

-formed by 2 cell types:
-epitheloid cells aka macrophages
-multinucleated giant cells (cytoplasmic fusion of macrophages fue to stimulation with macrophages)

65
Q

what is the next layer after the central focus of granulomas

A

lymphocytes

66
Q

what is the outerlayer of schisto granuloma

A

fibroblasts

67
Q

what is the immune response of schisto

A

-th1
-aimed at adult worm in early stages which shifts to eggs induced th2 biased profile 6 weeks post infection

68
Q

in schisto; egg antigens directly suppress what type of response

A

th1 response

69
Q

Major components of the granulomatous response to schistosome eggs in the host liver and the main cytokines and chemokines that regulate
this response. what are the cytokines and chemokines

A

-il 17, 23, 4, 19, 13 and 5

70
Q

what is the difference between the 2 pathologies of schisto

A

-severe: th17, th1 and th2
-mild: th2 and treg

71
Q

Schistosoma infection triggers a Th2 type response: which types of antigens and cells are involved

A

-ige
-mast cells
-eosinophila aka il4-5

72
Q

how is adcc induced in shisto

A

-by the interaction between the ige and igg with fd receptors on eosinophils

73
Q

ige dependant killing in shisto is mediated by what

A

eosinophils

74
Q

what are the other ways for ig isotypes to also kill

A

-toi, rni etc

75
Q

do people with schisto develop age dependent development of immunity

A

yup the egg counts go lower with age

76
Q

what is the correlation with igg titers and reinfection

A

-negative
-aka low igg=high egg count
-high igg=low egg amount

77
Q

what is the correlation between igm titers and reinfection

A

-high igm=high egg count aka it is positive

78
Q

ig in shisto is associated with what

A

protection

79
Q

Diagnosis: intestinal schistosomiasis

A
  1. History of freshwater exposure
  2. Stool for O&P (egg counts and viability)
  3. Serology– Elisa and Western Blot
  4. Antigen capture
  5. Eosinophilia
  6. Rectal snips or biopsies
  7. Liver biopsy
  8. Ultrasound or CT of abdomen
80
Q

tests based on the detection of schisto antigens what happens?

A

-become positive as soon as antigens are present and become negative quickly after cure

81
Q

monoclonal antibodies to schisto antigens have led to what

A

to the development of sensitive dot immuno assays aka very small sample quantities

82
Q

treatment to schisto

A

Drug: Praziquantel - WHO recommended dose
40 mg/kg body weight
In case of treatment failure;
S. mansoni - Oxamniquine
S. haematobium – Metrifonate

83
Q

are there any vaccines for schisto

A

nope

84
Q
A