Schistosomiasis

Question 1

What are the species that cause schistosomiasis and what is their geographical breakdown?

Answer 1

Schistosoma mansoni- subS African,a Yemen, Egypt, S. America

S. Japonicum- china and Philippines

S. Intercalatum- east and central Africa

S. Haematobium- subS Africa, Egypt, Yemen

Question 2

How do y u get infected with schistosomiasis?

Answer 2

Cercariae in water penetrate skin

Question 3

Where do the adult schistoma worms live and how do they get there?

Answer 3

Migrate and pair up in liver then live in venous plexuses of gut or bladder

Question 4

What is the pathogenesis of schistosomiasis?

Answer 4

Eggs are released but don’t end up in stool or urine, granulomas form around them and become fibrotic

Question 5

What are the non human stages of the schistoma life cycle?

Answer 5

Eggs in stool/ urine hatch into miracidia in the water and penetrate snails.
Cercariae are then released from snail

Question 6

What species of snail is a vector for schistoma mansoni?

Answer 6

Biomphalaria

Question 7

What species of snail is a vector for schistoma haematobium and intercalatum?

Answer 7

Bulinus

Question 8

What species of snail is a vector for schistoma japonicum?

Answer 8

Oncomelania

Question 9

Which species of schistoma have eggs in the stool?

Answer 9

Japonicum
Intercalatum
Mansoni

Question 10

Which species of schistoma have eggs in the urine?

Answer 10

Haematobium

Question 11

What are the dermal signs of schistosomiasis?

Answer 11

Cercarial dermatitis- itchy red spots where penetration has occurred

Question 12

What are the features of schistosomiasis in children?

Answer 12

Impaired cognitive development
Stunted growth
Anaemia
Nephrotic syndrome

Question 13

What is katayama fever?

Answer 13

4-6 wks after exposure to schistosomiasis

Fever, cough, diarrhoea, eosinophilia, hepatosplenomegaly

Question 14

What are the intestinal sequelae of schistosomiasis and which species cause them?

Answer 14

Mansoni and japonicum
Bloody diarrhoea
Hepatomegaly
Liver fibrosis- PV hypertensionsion- splenomegaly

Question 15

What causes pathology in schistosomiasis?

Answer 15

The eggs lead to granulomas and then fibrosis

Question 16

What are the urogenital signs of schistosomiasis and which species causes them?

Answer 16

Haematobium
Haematuria
Cystitis
Obstructive uropathy-> CKD
Squamous cell carcinoma
Haemospermia
Cervix/vulva inflammation-> bleeding

Question 17

What are the pulmonary sequelae of schistosomiasis?

Answer 17

Pulmonary hypertension-> RV heart failure

Question 18

What are the neurological sequelae of schistosomiasis?

Answer 18

Japonicum - lesions in brain
Mansoni and haematobium -in spinal cord

Very rare

Question 19

What does the mansoni egg look like?

Answer 19

Lateral spine

150microm

Question 20

What does the japonicum egg look like?

Answer 20

Round and often can’t see small spine

90 microm

Question 21

What does the haematobium egg look like?

Answer 21

Terminal spine

145 microm

Question 22

What does the intercalatum egg look like?

Answer 22

Terminal spine, central bulge

100-200 microm

Question 23

How do you diagnose schistosomiasis?

Answer 23

Stool and urine parasitology but low sensitivity
Urine POC circulating catholic antigen for mansoni
IgM/IgG antibody but can’t tell acute so not useful in endemic
Hatching- hatch eggs into miracidia, can use larger sample so more sensitive
PCR

Question 24

How do you treat schistosomiasis?

Answer 24

Praziquantel single dose

No severe organ damage reversal

Question 25

How do you prevent schistosomiasis?

Answer 25

Mass drug administration based on prevalence
Water sanitation, don’t stand in water to wash
Education
Chemicals to kill snails or release fish that eat them