Schistosoma haematobium

Schistosoma haematobium (urinary blood fluke) is species of digenetic trematode, belonging to a group (genus) of blood flukes (Schistosoma). It is found in Africa and the Middle East. It is the major agent of schistosomiasis, the most prevalent parasitic infection in humans. It is the only blood fluke that infects the urinary tract, causing urinary schistosomiasis, and is the leading cause of bladder cancer (only next to tobacco smoking). The diseases are caused by the eggs. Adults are found in the venous plexuses around the urinary bladder and the released eggs travels to the wall of the urine bladder causing haematuria and fibrosis of the bladder. The bladder becomes calcified, and there is increased pressure on ureters and kidneys otherwise known as hydronephrosis. Inflammation of the genitals due to S. haematobium may contribute to the propagation of HIV. S. haematobium was the first blood fluke discovered. Theodor Bilharz, a German surgeon working in Cairo, identified the parasite as a causative agent of urinary infection in 1851. After the discoverer, the infection (generally including all schistosome infections) was called bilharzia or bilharziasis. Along with other helminth parasites Clonorchis sinensis and Opisthorchis viverrini, S. haematobium was declared as Group 1 (extensively proven) carcinogens by the WHO International Agency for Research on Cancer (IARC) Working Group on the Evaluation of Carcinogenic Risks to Humans in 2009. Bloody urine (haematurea) was recorded by Ancient Egyptians in papyri 5,000 years ago. They called it Aaa. The first scientific report was by Marc Armand Ruffer, an English physician in Egypt, in 1910. He discovered parasite eggs from two mummies, which were dated to around 1,250–1,000 BCE. The oldest infection known to date was revealed using ELISA, which is more than 5,000 years old. In 1851, Theodor Maximillian Bilharz, a German physician at the Kasr el-Aini Hospital in Cairo recovered the adult fluke from a dead soldier. He named it Distomum haematobium, for its apparent two mouths (now called ventral and oral suckers) and habitat of the blood vessel. He published the formal description in 1852. The genus Distomum (literally 'two-mouthed') was created by Carl Linnaeus in 1758 for all flukes; hence, it was not specific. Another German physician Heinrich Meckel von Hemsbach introduced a new name Bilharzia haematobium in 1856 to honour the discoverer. He also introduced the medical term bilharzia or bilharziasis to describe the infection. Unbeknown to von Hemsbach, a German zoologist David Friedrich Weinland established a new genus Schistosoma in 1858. After almost a century of taxonomic dispute, Schistosoma was validated by ICZN in 1954; thereby validating the name Schistosoma haematobium. The infectious nature was discovered by Scottish physician Robert Thomson Leiper in 1915. He successfully infected mice, rats, guinea pigs, and monkey using cercariae from four species of snails, belonging to Bullinus (now Bulinus) and Planorbis, which were collected from El Marg canal near Cairo; proving that snails are the intermediate hosts. Its role in cancer was first noted by a British Surgeon Reginald Harrison, at the Liverpool Royal Infirmary, in 1889. He recorded that four people out of five cancer victims had bilharzia. A German physician Carl Goebel confirmed in 1903 that bladder tumour occurred in most bilharzia patients. By 1905, he was convinced that carcinoma of bladder was due to bilharzia. After decades of assessing the medical reports, it was finally declared by the WHO International Agency for Research on Cancer (IARC) Working Group on the Evaluation of Carcinogenic Risks to Humans in 2009 that S. haematobium is Group 1 carcinogen. Adult Schistosoma haematobium has male and female, which are permanently paired (a condition called in copula) as what looks like an individual. The male forms the flatworm part, measuring 10–18 mm in length and 1 mm in width. It bears oral and ventral suckers towards its anterior end. Its leaf-like flat body is curled up from both sides to form a channel or groove called gynaecophoric canal in which the female is wrapped up. Thus, it gives the general appearance of a cylindrical roundworm body. Only the extreme anterior and posterior ends of the female are exposed. In contrast to the male, a female exhibits every feature of a roundworm. It is cylindrical and elongated, measuring about 20 mm in length and 0.25 mm in width. Its pathogenic armament, the eggs are oval-shaped, measuring 144 x 58 µm in diameter, with characteristic terminal spine. This is an important diagnostic tool because co-infection with S. mansoni (having a lateral-spined eggs) is common. The miracidium measures about 136 μm long and 55 μm wide. The body is covered by anucleate epidermal plates separated by epidermal ridges. The epidermal cells give off numerous hair-like cilia on the body surface. Epidermal plate is absent only at the extreme anterior called apical papilla, or terebratorium, which contains numerous sensory organelles. Its internal body is almost fully filled with glycogen particles and vesicles.