Schistosoma sp.

Question 1

What phylum does the family schistosoma belong to?

Answer 1

Platyhelminthes

Question 2

What class does the family schistosoma belong to?

Answer 2

Trematoda

Question 3

In regards to the lifecycle of all trematodes, what occurs first.

Answer 3

-Egg, which contains miracidium, gets into environement

Question 4

In regards to the lifecycle of all trematodes, what happens once the miricidium comes into contact with water?

Answer 4

-Since the intermediate host for all trematodes are aquatic snails, it tries to locate the snail (host specific)

Question 5

In regards to the lifecycle of all trematodes, what happens after miracidium multiplies in the snail host?

Answer 5

Produced Cercaria into environment, which attach to various aquatic animals (Fasciola, Paragonimus, Clonorchis… NOT schistosoma)

Question 6

In regards to the lifecycle of all trematodes, what happens after cercaria attaches to various aquatic animals?

Answer 6

Becomes Metacercaria, which is expelled and ingested into human host.

Question 7

Do schistosoma have a Metacercaria stage?

Answer 7

• No (not food borne).
• Cercaria directly infect humans after being released from snail
• Skin penetration (different from other species)

Question 8

Is S. haematobium a zoonosis?

Answer 8

NO

Question 9

What are the intermediate hosts for S. Haematobium?

Answer 9

-Bulinus snails

Question 10

What is the definitive host for S. Haematobium?

Answer 10

Humans

Question 11

Where does one typically find S. haematobium?

Answer 11

• Africa
• Mid east
• Indian ocean islands
• India

Question 12

What is the intermediate host for S. mansoni?

Answer 12

-Biomphalaria (snail)

Question 13

What is the intermediate host for S. japonicum?

Answer 13

-Oncomelania (snail)

Question 14

Where does one typically find S. mansoni?

Answer 14

• Africa
• South America
• Central and Eastern Caribbean

Question 15

Where does one typically find S. japonicum?

Answer 15

• China
• Philippines
• Taiwan
• Indonesia

Question 16

Where is the predilection site for S. Haematobium?

Answer 16

Venous plexus of bladder

female parasite lives inside male pouch and receives nutrients

Question 17

How is S. haematobium released back into the environment from human hosts?

Answer 17

Eggs released from urine

Question 18

What is the most common way to get schistosomiasis?

Answer 18

Swimming in a water body in an endemic area (mid day)

any water activity

Question 19

What are the clinical symptoms of S. Haematobium?

Answer 19

1) Swimmer’s itch (0-3 days)
2) Migration = schistomular pneumonitis (3-10 days)
3) Egg laying immune response = “Acute schisto” Katayama fever with hyperosinophilia (3-6 weeks)
4) Chronic = ova trapped in bladder & urethra causing thickening, occlusion, hydronephrosis, hematuria + anemia, polyps - cancer

Question 20

Who are most at risk for infection of S. Haematobium?

Answer 20

kids ages 2-9

Question 21

How does one directly diagnose S. Haematobium infection?

Answer 21

Detection of eggs in urine (wont find in first daily urination)

Question 22

How does one indirectly diagnose S. Haematobium?

Answer 22

• Haematuria dip stick (blood in urine)
• Serology
• Imaging (cystoscopy, radiography, ultrasound for morbidity assesment)

Question 23

What is the treatment for S. Haematobium

Answer 23

Praziquantel (reverse state for children in 6 mo)

Question 24

What control would one use for S. Haematobium?

Answer 24

• Kill the parasite with chemotherapy
• kill the snails with molluscicides, prevent contamination water, prevent exposure areas near water reservoirs/high rain fall/ low altitude altitude greatest risk.