Schistosomiasis

Question 1

How is schistosoma transmitted?

Answer 1

Transdermal from freshwater

Question 2

Where does schistosoma mature?

Answer 2

Blood vascular system of the definitive host

Question 3

Schistosomiasis is associated with what symptoms?

Answer 3

Renal, bladder dysfunction, liver or intestinal disease

Question 4

Which Schistosoma species are intestinal?

Answer 4

S. mansoni and S. japonicum

Question 5

Which Schistosoma species is urogenital?

Answer 5

S. haematobium

Question 6

Which Schistosoma species is the most widely distributed and is endemic in Sub-Saharan Africa, South America and the Caribbean?

Answer 6

S. mansoni

Question 7

What is the life cycle of Schistosoma?

Answer 7

Cercariae in freshwater penetrates the skin
The head remains inside the skin for 2-3 days
Cercariae become schistosomula and enter the capillary bed or lymphatic system, then the lungs
Larvae matures in the liver
Male and female copulate and enter the mesenteric vein
Eggs retained in the liver causes chronic schistosomiasis
Eggs released in feces (S, japonicum and S. mansoni) or urine (S. haematobium)
Miracidia hatch and penetrate intermediate host
Miracidia develop into sporocysts and produce cercariae

Question 8

Where does the female worm reside?

Answer 8

Gynecophoric channel of the adult male

Question 9

How many days does it take for eggs to mature into miracidium?

Answer 9

8-10 days

Question 10

How is egg migration through tissues facilitated?

Answer 10

Release of enzymes by the miracidium

Question 11

How many days do the eggs live in tissue before dying?

Answer 11

21 days

Question 12

What is the intermediate host of S. haematobium?

Answer 12

Bulinus

Question 13

What is the intermediate host of S. mansoni?

Answer 13

Biomphalaria

Question 14

What is the intermediate host of S. japonicum?

Answer 14

Oncomelania

Question 15

How many days do cercariae live?

Answer 15

3-4 days

Question 16

The penetration of cercariae into the host skin is triggered by what?

Answer 16

Chemical and thermal stimuli

Question 17

Which side of the heart do schistosomules enter first?

Answer 17

Right side

Question 18

Which side of the heart do schistosomules enter before going into the systemic circulation?

Answer 18

Left side

Question 19

What do juvenile parasites feed on?

Answer 19

Erythrocytes

Question 20

What is the cause of pathology in schistosomiasis?

Answer 20

Egg deposition in the tissues

Question 21

How long do adult worms live?

Answer 21

3-8 years

Question 22

Cercarial penetration causes which skin conditions?

Answer 22

Cercarial dermatitis and swimmers itch

Question 23

Which antibody mediates the cercarial dermatitis hypersensitivity response?

Answer 23

IgE

Question 24

Which Schistosoma causes cercarial dermatitis?

Answer 24

S. mansoni

Question 25

Which Schistosoma causes swimmers itch?

Answer 25

Avian schistosomes

Question 26

What is the acute stage of schistosomiasis called?

Answer 26

Katayama fever

Question 27

True or false: Acute schistosomiasis is the response to sudden high level of antigen exposure

Answer 27

True

Question 28

What are some clinical symptoms of acute schistosomiasis?

Answer 28

Skin rashes, malaise, diarrhea

Question 29

Katayama fever is common for which Schistosoma species?

Answer 29

S. japonicum

Question 30

What is the hepatic pathology?

Answer 30

Accumulation of eggs and fibrotic reactions in the liver lead to cirrhosis and portal hypertension

Question 31

What is the intestinal pathology?

Answer 31

Ascites

Question 32

Which Schistosoma species causes fibrosis in the bladder, leading to ureteric obstruction and renal failure?

Answer 32

S. haematobium

Question 33

True or false: Chronic infection with S. mansoni does not lead to growth retardation

Answer 33

False, it does

Question 34

What triggers delayed-type hypersensitivity (DTH) reactions?

Answer 34

Antigen leakage

Question 35

What are the eggs surrounded by in the tissues?

Answer 35

Granuloma

Question 36

What forms the central focus of the granuloma?

Answer 36

Epitheloid cells and multinucleated giant cells

Question 37

What forms the middle layer of the granuloma?

Answer 37

Lymphocytes

Question 38

What forms the outer layer of the granuloma?

Answer 38

Fibroblasts

Question 39

What life stage of the Schistosoma parasite triggers a Th1 reaction?

Answer 39

Adult worm

Question 40

What life stage of the Schistosoma parasite triggers a Th2 reaction?

Answer 40

Eggs

Question 41

What directly suppresses the Th1 response?

Answer 41

Egg antigens

Question 42

What are other immune responses in Schistosomiasis?

Answer 42

IL-5 and eosinophilia

Question 43

What can be induced by the interaction of antibodies with Fc receptors on eosinophils?

Answer 43

ADCC (antibody-dependent cellular cytotoxicity)

Question 44

IgE dependent killing is mediated by which immune cells?

Answer 44

Eosinophils

Question 45

What age group is most affected and why?

Answer 45

Children because they express the wrong antibodies

Question 46

True or false: Protective responses take years to acquire

Answer 46

True

Question 47

True or false: Resistance is high in younger populations

Answer 47

False, it is high in older populations

Question 48

Low IgG is associated with what level of eggs?

Answer 48

High egg count

Question 49

Which antibody apart from IgE is protective?

Answer 49

IgG

Question 50

Which antibody response is not protective?

Answer 50

IgM

Question 51

IgE levels are highest in which individuals?

Answer 51

R individuals

Question 52

The following diagnostic techniques are used to detect which type of schistosomiasis? a. History of freshwater exposure b. Stool for O&P (egg counts and viability) c. Rectal snips or biopsies

Answer 52

Intestinal Schistosomiasis

Question 53

The following diagnostic techniques are used to detect which type of schistosomiasis? a. History of freshwater exposure b. Urine for eggs c. Cystoscopy - trigone appearance

Answer 53

Urinary Schistosomiasis

Question 54

What is the main drug for treating schistosomiasis?

Answer 54

Praziquantel

Question 55

What are the drugs used in case of treatment failure?

Answer 55

S. mansoni - Oxamniquine S. haematobium - Metrifonate

Question 56

True or false: Vaccines are used to treat schistosomiasis

Answer 56

False