- Separate sexes.
- Oesophagus bifurcates into 2 simple intestinal caeca that unite again giving a single caecum that ends blindly.
- Male is folded on itself forming a gynecophoric canal and has 4-9 small testes.
- Female is longer than male with a cylindrical body , single ovary and uterus.
Schistosomes.
The main species affect humans :
- Schistosoma haematobium
- Schistosoma mansoni
*Infective stage: Furcocercous cercaria.
*Mode of infection :penetration of skin or buccal mucosa by cercaria.
- Eggs pass mature with urine (S. haematobium) and faeces (S.mansoni).
- Eggs hatch liberating miracidium that enters snail and develops inside to sporocyst and cercaria (NO REDIA).
- Furcocercous cercaria (has forked tail) comes out of snail and swims in water (NO METACERCARIA).
Diagnosis.
I. Clinical diagnosis: Clinical picture.
II. Laboratory diagnosis:
1- Stool (intestinal schistosomiasis) or urine (urinary schistosomaiasis) examination for detection of eggs (diagnostic stage). Eggs don’t not pass in urine or stool
in chronic schistosomiasis when there is fibrosis preventing passage of eggs.
2- Cystoscope or Sigmoidoscope to take biopsy.
3- Serological by detection of antibodies in patient sera.
4- Blood examination: anaemia.
Treatment.
1- Praziquantel: effective in all forms of schistosomiasis both in acute stage and late stages
Dose : 40 mg / kg in a single oral dose
2- Oxamniquine : is effective in S. mansoni only
Dose :30 mg / kg / day on two doses for 2 days
3- Treatment of swimmer’s itch by antipruritic lotions and antibiotics for secondary infections .
Control of schistosomiasis.
I. Measures dealing with man :
1- Treating patients.
2- Health education.
3- Safe water supply.
II. Snail control :
A- mechanical control:
1- Scraping wall of canal to remove weeds and snails.
2- Increase slopes of canal or divert away from population.
B- Biological control: enhance growth of snail enemies like gambusia fish.
C- Chemical control by molluscicide such as Bayluscide Follow Us
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