TREMATODES – SCHISTOSOMA HAEMATOBIUM

Definition:

• Schistosoma haematobium is a parasitic flatworm that causes urinary schistosomiasis.
• It is a type of trematode.

Causes:

• The disease is caused by the S. haematobium parasite.
• The parasite is usually found in freshwater habitats such as lakes, rivers, and ponds.

Types:

• There are several species of Schistosoma, but S. haematobium is the most common cause of urinary schistosomiasis.

• Other species like S. mansoni, S. japonicum, and S. mekongi can also cause the disease. Morphology of Schistosoma haematobium

• It is a parasitic flatworm (trematode) that infects the human urinary system.

• The adult worm is a pinkish-white, thread-like structure, about 1-2 cm long.

• The female worm has a distinct pair of reproductive organs called the ovary and the ovary sac.

• The male worm has a pair of reproductive organs called the testis and the vas deferens.

• The worm's body is covered with a thin layer of skin called the tegument.

Life Cycle of Schistosoma haematobium

1. → The worm eggs are released into the urine of an infected person.
2. → The eggs hatch into larvae called miracidia in freshwater environments.
3. → The miracidia infect a freshwater snail called the intermediate host.
4. → Inside the snail, the miracidia undergo asexual reproduction and form a mass of larvae called sporocysts.
5. → The sporocysts then form a mass of larvae called cercariae.
6. → The cercariae are released from the snail and infect a human host through contact with contaminated water.
7. → The cercariae penetrate the skin and enter the bloodstream.
8. → The cercariae then mature into adult worms in the human urinary system.

Pathogenicity and Clinical Features of Bilharziasis

• Bilharziasis is a disease caused by the infection of Schistosoma haematobium.
• The disease is known as urinary schistosomiasis.
• The worm's eggs cause inflammation and damage to the bladder and ureters.
• The disease can cause symptoms such as:
  • Blood in the urine (hematuria)
  • Abdominal pain
  • Urinary frequency and urgency
  • Urinary tract infections
  • Bladder cancer
• The disease can also cause long-term complications such as:
  • Bladder damage
  • Kidney damage
  • Urinary tract problems
  • Increased risk of bladder cancer

Lab Diagnosis of Bilharziasis

• Urine examination:
  • Microscopic examination of urine for eggs
  • Urine filtration for eggs
• Blood examination:
  • Serological tests for antibodies against Schistosoma haematobium
• Stool examination:
  • Examination of stool for eggs
• Snail examination:
  • Examination of snails for the presence of cercariae
• Imaging studies:
  • Ultrasound and CT scans to visualize the urinary system
  • MRI scans to visualize the bladder and ureters

Memory Trick: "Eggs Hatched in Snails, Cercariae Infect Humans, Worms Mature, Eggs Are Passed"

This memory trick helps to remember the life cycle of Schistosoma haematobium in a simple and easy-to-remember way.

Clinical Features:

• The main symptom of urinary schistosomiasis is hematuria (blood in the urine).
• Other symptoms include dysuria (painful urination), frequency of urination, and abdominal pain.
• In severe cases, the disease can cause bladder cancer and kidney damage.

Complications:

• Chronic infection with S. haematobium can lead to bladder cancer.
• The disease can also cause kidney damage and infertility.
• In severe cases, the disease can cause intestinal obstruction.

Diagnosis:

• The disease can be diagnosed by identifying the eggs of the parasite in the urine.
• Other diagnostic methods include blood tests and imaging studies.

Management:

• The treatment of choice for urinary schistosomiasis is praziquantel.
• Other treatments such as oxamniquine and metrifonate may also be used.
• Preventive measures include avoiding contact with contaminated water and using protective clothing.

Memory Trick: "Penis in the urine, haematobium is the cause, schistosomiasis is the disease, beware of the snail's parasite, S. haematobium is the name."

Exam Tips:

• Bilharziasis is a disease caused by the infection of Schistosoma haematobium.
• The disease is known as urinary schistosomiasis.
• The worm's eggs cause inflammation and damage to the bladder and ureters.
• The disease can cause symptoms such as blood in the urine, abdominal pain, and urinary frequency and urgency.
• The disease can also cause long-term complications such as bladder damage, kidney damage, and urinary tract problems.
• The lab diagnosis of Bilharziasis involves urine examination, blood examination, stool examination, snail examination, and imaging studies.