What is the name of the parasite with barbs that stick in the urethra?

Schistosoma haematobium

The parasite you're referring to is Schistosoma haematobium, which causes urogenital schistosomiasis and is characterized by eggs with a terminal spine that can become embedded in the bladder and urethral tissues. 1, 2

Parasite Characteristics and Mechanism

• S. haematobium is a blood fluke (trematode) that specifically infects the genitourinary system, distinguishing it from other Schistosoma species. 2

• The eggs of S. haematobium possess a terminal spine (a barb-like projection at one end) that facilitates their embedding into the bladder wall and urethral tissues, causing the characteristic tissue damage and symptoms. 2

• These eggs become trapped in the bladder wall and urethral mucosa, where they elicit chronic immune-mediated inflammatory responses and granuloma formation. 2, 3

Geographic Distribution and Transmission

• This parasite is endemic to Africa and the Middle East, though cases are increasingly seen elsewhere due to travel and immigration. 2, 4

• Transmission occurs through exposure to freshwater containing cercariae released by infected freshwater snails. 5, 4

Clinical Presentation

• Classic urogenital symptoms include hematuria (blood in urine), dysuria (painful urination), and hemospermia (blood in semen), typically appearing within 3 months of infection. 2

• The condition can present with haematuria, proteinuria, dysuria, haematospermia, and inter-menstrual bleeding in women. 1

• In acute infection (Katayama syndrome), patients may develop fever, urticarial rash, and marked eosinophilia 2-8 weeks after freshwater exposure. 1

Diagnostic Pitfalls

• Misdiagnosis is common in non-endemic areas, with cases mistaken for ureteral calculus, bladder cancer, or eosinophilic cystitis. 4

• Definitive diagnosis requires detection of parasite ova on microscopic urinalysis of terminal urine, though serology can be helpful when egg detection is negative. 1, 2

• Fine ureteral calcifications appearing as parallel lines on imaging are considered pathognomonic of early-stage schistosomiasis. 2

Treatment

• Praziquantel 40 mg/kg as a single oral dose is the first-line treatment for all S. haematobium infections. 6

• Treatment is highly effective when administered promptly after diagnosis. 5

Long-term Complications

• Chronic infection leads to bladder fibrosis, calcification, and strictures, creating a predisposition to squamous cell carcinoma of the bladder. 2, 3

• The parasite is recognized as a predisposing factor for HIV/AIDS transmission. 3