Schistosomiasis

Question 1

Name the three genus’ of Schistosoma

Answer 1

S.mansoni, S.haematobium, S.japonicum

Question 2

In order (from hatching from the eggs to producing eggs) name the intermediate forms of the parasite

Answer 2

eggs hatch and release MIRACIDIA, these enter snails and form SPOROCYSTS (2 gen) which release from snails and are CERCARIAE, which enter mammals and form SCHISTOSOMULAE, which mature and lay eggs

Question 3

In endemic areas, which stage of a humans life does the worm number peak?

Answer 3

Teens, reduced in adult

Question 4

What is the life span of the adult in the human host?

Answer 4

Over 30 years

Question 5

What is the immune response during the skin penetration stage?

Answer 5

Ab reaction to cercariae surface coat, and to secretions from penetration glands. Th1 response.

Question 6

Describe and explain granuloma formation

Answer 6

Schistosomulae eggs lodged in sinusoidal capsules of liver and CD4+ activity induced by SEA. RAPID AND VIGOROUS. Elevated e-selectin and ICAM-1. More ICAM-1 = larger granuloma. Lewisx on SEA can cause immune response!

Question 7

Which stage/s cause Th1/Th2?

Answer 7

Schistosomulae/egg = Th2, penetration stage - cercariae = Th1

Question 8

What cellular changes take place in the host in response to infection and what effect do they have?

Answer 8

In response to contact with schist eggs, oxidative stress in ENTIRE LIVER, activation of H2O2/peroxidase system leads to egg killing.

Question 9

What role do IgE/eosinophils play in infection?

Answer 9

Immunity correlates with IgE levels! These increase w/age. Schistosomulae are killed by opsonization with IgE and eosinophils degranulating.

Question 10

What special shiz goes on with immune evasion during a schist infection?

Answer 10

HOST MIMICRY, WAT SON. This is ‘host antigen aquisition’. Adult worms become coated with host proteins. Ends in negligible inflammation around the adult worm!

Question 11

What is the first pathology noticed of schistosomiasis?

Answer 11

Local irritation, raised spots lasting a few days

Question 12

What is Katayama Syndrome?

Answer 12

Associated with S.mansoni and S.japonicum. Type 3 hypsensreac to high antigen levels. 2-12 weeks post infec. Abrupt fever/malaise/aches/dry cough. Liver/spleen enlarged. High eosin count.

Question 13

How is schist diagnosed - 3 ways

Answer 13

1) urine and stool, egg shedding at midday. 2)if no eggs, endoscopy/biopsy/ultrasonography 3)Blood serum IgE from Th2 but can take 12 weeks p.i. to develop

Question 14

Vaccine targets?

Answer 14

Larval stage, before schist/worm attain protection