Page 145 - Medical Parasitology_ A Textbook ( PDFDrive )

138 12 Trematodes: Flukes

haematuria. Haematuria is initially microscopic, but become gross in heavy infec-
tion. Patients develop frequency of micturition with burning sensation. Cystoscopy
shows hyperplasia and inflammation of bladder mucosa. In the chronic stage, there
is generalized hyperplasia and fibrosis of the bladder mucosa with a granular appear-
ance (sandy patch). At the sites of deposition of the eggs, there is dense infiltration
with lymphocytes, plasma cells and eosinophils. Initially, the trigone is involved,
but as it progresses, the entire mucosa becomes inflamed, thickened and ulcerated.
Calculi form in the bladder around the eggs and blood clots. There may be obstruc-
tive hyperplasia of the ureters and urethra. Chronic urinary schistosomiasis has been
associated with squamous cell carcinoma of the bladder.

Diagnosis
1. Microscopic examination
Detection of eggs with characteristic terminal spines in centrifuged urine
sample. Eggs which are deposited in rectum may be occasionally found in
faeces.
2. Biopsy
Bladder mucosa or rectal biopsies to demonstrate eggs.
3. Serodiagnosis
4. Molecular diagnosis
PCR on clinical samples.

Treatment
Praziquantel (40 mg/kg/day orally in 2 divided doses for 1 day) is the drug of choice.
Metrifonate is the alternative drug.

Prevention and Control
1. Proper disposal of urine and faeces
2. Treatment of infected persons
3. Avoid swimming, bathing and washing in snail-infested water
4. Control of snails

Schistosoma mansoni

Distribution
It is widely distributed in Africa, South America and the Caribbean islands.

Habitat
Adult worm lives in the inferior mesenteric vein.

Morphology
Schistosoma mansoni resembles S. haematobium in morphology and life cycles,
except the adult worms are smaller and their integuments are covered with coarse