Flukes

Question 1

What class do flukes belong to?

Answer 1

Trematoda

Question 2

In general what shape are adult trematoda flukes>

Answer 2

Flattened and leaf-like

Question 3

What type of flukes are the Schistosoma genus?

Answer 3

Blood flukes

Question 4

Describe the Schistosoma flukes.

Answer 4

• Cylindrical adult worms - Separate sexes - Indirect life-cycle: single intermediate host

Question 5

How are Schistosoma flukes transmitted?

Answer 5

Human transmission via skin penetration by larvae

Question 6

Name three different species of Schistosoma and where they are found.

Answer 6

1. Schistosoma haematobium = Africa and Middle East 2. Schistosoma mansoni = Africa 3. Schistosoma japonicum = Far East

Question 7

Which species of Schistosoma are found in RSA?

Answer 7

S. Africa S. haemotobium S. mansoni

Question 8

Name four stages of Schistosomiasis caused by fluke infestation.

Answer 8

1. Cercarial dermatitis (Swimmer’s Itch) 2. Katayama fever 3. Chronic established infection 4. Late infection (complication: fibrosis)

Question 9

Describe the Katayama stage of Schistosomiasis.

Answer 9

• 2 weeks - 2 months after exposure - Maturation - Early egg laying - Hypersensitivity response (fever, hepatosplenomegaly, lymphadenopathy, cough and eosinophillia)

Question 10

Describe the chronic stage of Schistosomiasis.

Answer 10

• Intense egg laying - S. haematobium = terminal haematuria - S. mansoni = abdominal pain and dysentry (rare)

Question 11

Describe the late infection stage of Schistosomiasis.

Answer 11

• S. haematobium: ureteric obstruction hydronephrosis renal failure bladder carcinoma - S. mansoni: colonic stricture portal hypertension

Question 12

How do you diagnose Schistosomasis?

Answer 12

• Serology (1 month after infection) - Ova in urine/stool (1 month after infection) - Biopsy of bladder or rectal mucosa (rectal snip)

Question 13

What is the treatment for Schistosomiasis?

Answer 13

• Prazoquantel (treats all species) 30 mg per kilogram (twice daily)

Question 14

Explain the life-cycle of the schistosoma fluke?

Answer 14

Question 15

At which stage are Schistosoma species infectious?

Answer 15

Cercariae released by snail into water and free-swimming

Question 16

At which stage are Schistosoma species diagnosable?

Answer 16

Ova in the urine or feces

Question 17

Of S.haemotobium, S. mansoni and S. japoniucum where are the adult flukes located in the body respectively?

Answer 17

SH = Vesical plexus

SM = Mesenteric plexus and portal vein

SJ = Mesenteric plexus and portal vein

Question 18

Of S.haemotobium, S. mansoni and S. japoniucum what are their intermediate hosts respectively?

Answer 18

SH = Bulinus snail

SM = Biomphalaria snail

SJ = Onchomelania snail

Question 19

Of S.haemotobium, S. mansoni and S. japoniucum what is characteristic of their ova respectively?

Answer 19

SH = Terminal spine (urine)

SM = Lateral spine (feces)

SJ = Lateral knob (feces)

Question 20

List 7 methods of Schistomiasis prevention.

Answer 20

1. Access to treatment in endemic areas
2. Public education
3. Poper disposal of human excreta (sanitation facilities)
4. Provision of potable water to communities
5. Improve irrigation and agriculture practises
6. Prevent exposure to contaminated water (rubber boots)
7. Treat snail habitats/breeding sites with molluscicides

Question 21

What is geohelminth control?

Answer 21

An WHO mass treatment of school-age children where prevalence of infection is more than 50%