Overview
Also known as bilharzia, schistosomiasis describes an infection with parasitic worms, more specifically flukes (trematodes), of the Schistosoma genus. Three clinically-relevant species are:
- Schistosoma haematobium – infects the bladder, endemic in Africa and the Middle East
- Schistosoma mansoni – infects the colon and portal system, endemic in Egypt, Africa, the West Indies, and South America
- Schistosoma japonicum – infects the colon and portal system, endemic in Japan, China, and the Philippines
This section will focus on Schistosoma haematobium as it is a risk factor for bladder cancer.
Pathophysiology
Schistosoma haematobium causes bladder inflammation due to the worms depositing eggs. Depending on the eggs’ number, location, and progression of disease, obstructive uropathy and kidney damage may occur.
Presentation
Overview
Symptomatic infections tend to happen to travellers to endemic areas as they are not immune to the worms. Features include:
- ‘Swimmers itch’ – an allergic contact dermatitis reaction that occurs in infected skin
- Characterised by urticaria, pruritus, and papules
- General features – including fever, diarrhoea, myalgia, arthralgia
- Urinary symptoms – dysuria and haematuria
Investigations
Overview
Some investigations and their findings include:
- Full blood count (FBC) and differential: may show eosinophilia
- Abdominal X-ray: may show calcified areas representing eggs, not the bladder itself
- Serum Schistosoma antibodies: often performed in asymptomatic patients
- Urine or stool microscopy: often performed in symptomatic patients, shows eggs
Management
Overview
Management involves a single dose of praziquantel.
