Schistosoma sp. Flashcards
What phylum does the family schistosoma belong to?
Platyhelminthes
What class does the family schistosoma belong to?
Trematoda
In regards to the lifecycle of all trematodes, what occurs first.
-Egg, which contains miracidium, gets into environement
In regards to the lifecycle of all trematodes, what happens once the miricidium comes into contact with water?
-Since the intermediate host for all trematodes are aquatic snails, it tries to locate the snail (host specific)
In regards to the lifecycle of all trematodes, what happens after miracidium multiplies in the snail host?
Produced Cercaria into environment, which attach to various aquatic animals (Fasciola, Paragonimus, Clonorchis… NOT schistosoma)
In regards to the lifecycle of all trematodes, what happens after cercaria attaches to various aquatic animals?
Becomes Metacercaria, which is expelled and ingested into human host.
Do schistosoma have a Metacercaria stage?
- No (not food borne).
- Cercaria directly infect humans after being released from snail
- Skin penetration (different from other species)
Is S. haematobium a zoonosis?
NO
What are the intermediate hosts for S. Haematobium?
-Bulinus snails
What is the definitive host for S. Haematobium?
Humans
Where does one typically find S. haematobium?
- Africa
- Mid east
- Indian ocean islands
- India
What is the intermediate host for S. mansoni?
-Biomphalaria (snail)
What is the intermediate host for S. japonicum?
-Oncomelania (snail)
Where does one typically find S. mansoni?
- Africa
- South America
- Central and Eastern Caribbean
Where does one typically find S. japonicum?
- China
- Philippines
- Taiwan
- Indonesia
Where is the predilection site for S. Haematobium?
Venous plexus of bladder
female parasite lives inside male pouch and receives nutrients
How is S. haematobium released back into the environment from human hosts?
Eggs released from urine
What is the most common way to get schistosomiasis?
Swimming in a water body in an endemic area (mid day)
any water activity
What are the clinical symptoms of S. Haematobium?
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
Who are most at risk for infection of S. Haematobium?
kids ages 2-9
How does one directly diagnose S. Haematobium infection?
Detection of eggs in urine (wont find in first daily urination)
How does one indirectly diagnose S. Haematobium?
- Haematuria dip stick (blood in urine)
- Serology
- Imaging (cystoscopy, radiography, ultrasound for morbidity assesment)
What is the treatment for S. Haematobium
Praziquantel (reverse state for children in 6 mo)
What control would one use for S. Haematobium?
- 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.
