Schistosoma Haematobium: A Blood Fluke

Parasites have been known to infect humans since a time immemorial. Schistosoma haematobium is one such prominent digenetic parasite. This parasite belongs to the phylum Platyhelminthes and class Trematoda. The common name of this organism is blood fluke. It is extensively distributed in Middle East, India, Portugal and Africa. It causes a disease known as schistosomiasis but urinary schistosomiasis is commonly reported in citizen of these regions. Adults are known to inhabit the venous plexuses near the urinary bladder. The eggs are known to traverse the wall of urinary bladder and cause haematuria and fibrosis of the bladder. The bladder becomes calcified and the pressure on the ureters and kidneys is increase resulting in a condition known as hydronephrosis. Inflammation of the genital regions may help in the propagation of Hiv. This parasite may also be connected with the amelioration of the squamous cell carcinoma of urinary bladder.

The life cycle begins with the entry of the free swimming larval stage known as cercariae which burrows in the skin of the humans after drinking the contaminated water. The cercariae enter the blood stream and take their course to the liver where they mature into adult blood flukes. To remain protected by the supervene of the immune ideas the parasite is known to coat its body with the antigens of the host. They dwell in the liver after attaining maturity for a period of 3 weeks and they migrate towards the urinary bladder in order to copulate. The females are known to lay as much as 3,000 eggs per day in the lumen of the urinary bladder and ureters. The eggs leave the human body with the tube of urine exterior the body straight through the process of micturition. The eggs reach water where they hatch into the first larval stage known as miracidiae which enter the first intermediate snail which is a freshwater animal belonging to the genus Bulinus. Inside the body of the snail miracidium sheds its epithelium and becomes converted into an additional one larval stage known as sporocyst. After two weeks this sporocyst produces daughter sporocysts. After four weeks these sporocysts get converted into the cercariae stage. These cercariae leave the body of snail and come at the top of the water and wait in search of human host. Within half an hour they drill the epithelium of the human host.

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The determination can be done by microscopical test of urine for the detection of the eggs. In chronic infection when it becomes difficult to detach the eggs then an intradermal injection of schistosome antigen is given to form a wheal after which the parasite can be identified. Complement fixation tests can be performed. The root cause of the spread of infection is the dumping of human waste into water supplies. Productive disposal of waste can help in minimizing the infection. The immune ideas responds to the eggs in the liver by causing hypersensitivity. Hepatocytes are damaged as a supervene of immune response. The antibodies of the host bind to the tegument of the blood fluke but not for a longer period so the tegument is shed after every few hours. The parasite also takes some of the host proteins. Infection can be characterized by the nearnessy of acute inflammation, squamous metaplasia, blood and reactive epithelial changes. Granulomas and multinucleated cells are frequently observed. The infection can be treated by using drugs like praziquantel, a quinolone derivative.

Schistosoma Haematobium: A Blood Fluke

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