Schistosomiasis

Exam Cram

• Schistosomiasis is caused by parasitic worms of the genus Schistosoma

• S. Haematobium affects the urinary tract, causing haematuria and bladder cancer

• S. Mansoni affects the GI tract causing bloody diarrhoea & liver cirrhosis

• Management: praziquantel

Outline

Background

• Schistosoma is a type of parasitic worm: trematode fluke

• Classically associated with swimming in Lake Malawi. Associated with water based activities (swimming, fishing) and a lack of public health infrastructure.

• Rare in the UK and western world, worldwide has significant health burden, particularly in tropical and subtropical communities, 90% in Africa. 

• Adults live in blood vessels releasing eggs. The immune reaction is primarily towards the eggs. 

• Urinary schistosomiasis is the leading cause of bladder cancer in Africa (SCC)

Transmission

• The worm's larva live in freshwater snails, penetrate skin during contact with fresh water

• Schistosoma's eggs contaminate fresh water and are ingested

• Animals (including humans) transmit via the faecal oral route. 

Assessment

Presentation

Recent swimming in Lake Malawi is a classic MCQ 

Intestinal schistosomiasis

• Abdominal pain, diarrhoea, bloody stool

• Hepatosplenomegaly, ascites,  portal hypertension

• Katayama's fever: fever, dry cough, abdominal pain (worms move to lungs)

Urogenital schitosomiasis

• Haematuria (urinary)

• Genital lesions, vaginal bleeding 

Investigations

• Stool eggs search

• Schistosoma antibody serology

Diagnosis

Diagnostic criteria: clinical presentation with schistosoma microbiology

• Detect eggs in stool or urine

• Serum antibody detection

Classification: as per species within the Schistosoma genus 

Intestinal 

• Schistosoma mansoni

• Schistosoma japonicum- commonest cause of Katayama's fever

• Schistosoma mejongi

Urogenital 

• Schistosoma guineesnsis & intercalatum

• Schistosoma haematobium

Management

Acute

1. Praziquantel

Complications

• Bladder SCC Cancer

• Hydronephrosis

References

1. Schistosomiasis (no date) World Health Organization. Available at: https://www.who.int/news-room/fact-sheets/detail/schistosomiasis#:~:text=Schistosomiasis%20is%20an%20acute%20and,expose%20them%20to%20infested%20water. (Accessed: 08 October 2024).

Written in 2024