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(bĭl'härzī`əsĭs), or

snail fever,

parasitic disease caused by blood flukes, trematode worms of the genus Schistosoma. Three species are human parasites: S. mansoni, S. japonicum, and S. haematobium. The disease is prevalent in Asia, some Pacific islands, Africa, the West Indies, South America, Spain, Puerto Rico, and Cyprus. The larvae of the parasite are harbored by snails, which serve as intermediate hosts, and infect humans who bathe in or otherwise come in contact with infested waters. The larvae enter through the skin, migrate via the blood vessels, and mature in the lungs. From there they travel to the veins of the upper or lower intestine or bladder and reproduce. Some eggs pass out in the feces. Others are carried into the liver, where the body surrounds them with white blood cells, forming hundreds of tiny ball-like granulomas that eventually impair the liver's ability to function. It is believed that the flukes settle in blood vessels that have a particular human immune substance, tumor necrosis factor, that they require in order to reproduce.

The disease is characterized by a skin eruption at the site of entry, fever, diarrhea, and other symptoms, depending on the tissues affected; cirrhosis of the liver is common. The disease can be cured with the drug praziquantel, but reinfection can occur. Although symptoms vary according to the species of infecting fluke, all forms can result in general weakening and eventual death. Control of the disease is difficult, but control of the snail populations that serve as intermediate hosts is effective in reducing the incidence of the disease. Proper sanitation and disposal of human wastes are also important.



a disease of the urinary tract and intestine caused by parasitic worms—trematodes of the family Schistosomatidae. It was originally called bilharzia after the German physician T. Bilharz, who discovered the causative agent in 1851.



any one of several diseases of humans and animals caused by helminths of the family Schistosomatidae of the class Trematoda.

Schistosomiases of humans occur mainly in tropical countries. The causative agents belong to the genus Schistosoma, whose females deposit eggs in the small blood vessels of the urinary bladder and intestine. After entering these organs, the eggs are excreted with urine or feces. Larvae (miracidia) emerge from the eggs after they reach water and are ingested by mollusks, in which they reproduce and develop. The cycle is completed with the emergence of larvae with tails (cercariae) in the water. The cercariae penetrate the human body through the skin and mucous membranes. Individuals become infected after working or swimming in bodies of water contaminated by the urine and feces of persons suffering from schistosomiasis or after drinking water from such bodies of water.

Skin rashes, itching, and sometimes fever occur in the early stage of schistosomiasis. If the genitalia and intestine are affected (bilharziasis), the patient feels a sharp pain upon urination, the urine becomes tinged with blood, and chronic colitis, with mucus and blood appearing in the feces, develops. Schistosomiasis is treated with antimony agents, for example, Anthiomaline (or anthiolimine); it is also treated with Ambilhar (or niridazole). The disease can be prevented by protecting lakes and streams from pollution, by banning swimming in stagnant or slow-flowing water in areas where schistosomiasis is endemic, and by boiling drinking water or filtering it through cloth.



A disease in which humans are parasitized by any of three species of blood flukes: Schistosoma mansoni, S. haematobium, and S. japonicum; adult worms inhabit the blood vessels. Also known as bilharzias; snail fever.


a disease caused by infestation of the body with blood flukes of the genus Schistosoma
References in periodicals archive ?
The apparent increase in the frequency of TCC in Egypt, during the 10 years' period of study by Salem and Mahfouz, was also attributed to a decrease in the incidence of schistosomiasis.
c) Field surveys for common parasitic diseases in the area, mainly schistosomiasis and Kala-azar, snail intermediate hosts of schistosomiasis along the shores of the Blue Nile were conducted.
As part of the company's corporate responsibility efforts, Merck is committed to fighting the worm disease schistosomiasis until its elimination.
Parasitic diseases like nasal schistosomiasis are also sporadically reported.
The aim of this study was to evaluate the prevalence of past or present HEV infection in a sample of schistosomiasis patients in Recife, an endemic region of Northeastern, Brazil, and to associate the positivity to HEV infection to clinical and laboratory abnormalities.
The campaign aims to educate residents about the connection between schistosomiasis, which affects everyone in the town in some way, and sanitation.
Hence, irrespective of the criteria for a confirmed case of schistosomiasis described above, it appears difficult to conclude that confirmation could rely on only 1 positive serologic test, even a WB.
1] Schistosomiasis is an endemic in many countries, being not only in sub-Saharan Africa, but also the far East, South and Central America, and the Caribbean.
The existing gold standard' treatment for schistosomiasis is praziquantel (PZQ), which was developed by Merck KGaA, Darmstadt, Germany in the 1970s through a research collaboration.
The discovery of a Schistosomiasis parasite egg in a 6,200 year-old grave in Syria may be the earliest evidence that agricultural irrigation systems in the Middle East region contributed to a vast spread of disease.