The three main species infecting humans are Schistosoma haematobium, S. japonicum, and S. mansoni. Two other species, more localized. Schistosomiasis, also known as bilharzia, is a disease caused by parasitic Most human infections are caused by Schistosoma mansoni. Diagnosis for intestinal Schistosoma mansoni lacks sensitivity and is arduous to conduct. The standard diagnostic tests, Kato-Katz (KK) and circulating cathodic.
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Schistosomiasis is caused by digenetic blood trematodes. The three main species infecting humans are S chistosoma haematobiumS. Two other species, more localized geographically, are S.
Drugs for treating Schistosoma mansoni infection
In addition, other species of schistosomes, which parasitize birds and mammals, can cause cercarial dermatitis in humans. Eggs are eliminated with feces or urine. Under optimal conditions the eggs hatch and release miracidiawhich swim and penetrate specific snail intermediate hosts.
The stages in the snail include 2 generations of sporocysts. Upon release from the snail, the infective cercariae swim, penetrate the skin of the human hostand shed their forked tail, becoming schistosomulae. The schistosomulae migrate through several tissues and stages to their residence in the veins.
Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species.
However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. The females size 7 to 20 mm; males slightly smaller deposit eggs in the small venules of the portal and perivesical systems.
The eggs are moved progressively toward the lumen of the intestine S. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, hourse and goats, serve as reservoirs for S.
Schistosoma mekongi and S. Many infections are asymptomatic. Manifestations include fever, cough, abdominal pain, diarrhea, hepatosplenomegaly, and eosinophilia. Occasionally central nervous system lesions occur: Continuing infection may cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include: Images courtesy of the Wisconsin State Laboratory of Hygiene.
Note the small, inconspicuous spines red arrows. The spine is not visible in either of these specimens. Images courtesy of Dr.
Images courtesy of the Michael E. Medical Center, Houston, TX.
Mamsoni thin female resides in the gynecophoral canal of the thicker male. Note the tuberculate exterior of the male. Adults of Schistosoma sp. Higher magnification of one of the worms in Figure A, showing the tuberculate exterior of the adult worm. Adults of Schistosoma spp. Microscopic identification of eggs in stool or urine is the most practical method for diagnosis.
Stool examination should be performed when infection with S. Eggs can be present in the stool in infections with all Schistosoma species. The examination can be performed on a simple smear 1 to 2 mg of fecal material. In addition, for field surveys and investigational purposes, the egg output can be quantified by using the Kato-Katz technique 20 to 50 mg of fecal material or the Ritchie technique.
Eggs can be found in the urine in infections with S. Mansono will be enhanced by centrifugation and examination of the sediment. Tissue biopsy rectal biopsy for all species and biopsy of the bladder for S. Antibody detection can be useful to indicate schistosome infection in patients who have traveled in schistosomiasis endemic areas and in whom eggs cannot be demonstrated in fecal or urine specimens.
Schistosoma mansoni – Wikipedia
Test sensitivity and specificity vary widely among the many tests reported for the serologic diagnosis of schistosomiasis and are dependent on both the type of antigen preparations used crude, purified, adult worm, egg, cercarial and the test procedure.
At CDC, a combination of tests with purified adult worm antigens are used for antibody detection. Immunoblots with adult worm microsomal antigens are species-specific and so a positive reaction indicates the infecting species. The presence of antibody is indicative only of schistosome infection at some time and cannot be correlated with clinical status, worm burden, egg production, or prognosis.
Morphologic comparison with other intestinal parasites. Treatment information for schistosomiasis can be found at: DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.
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Recommend on Facebook Tweet Share Compartir. Life Cycle Eggs are eliminated with feces or urine. Image Gallery Schistosoma mansoni eggs. The anterior end is tapered and slightly curved. When the eggs are excreted in stool, they contain esquistoso,iasis mature miracidium. Eggs contain a mature miracidium when shed in urine. The spine on S. Eggs are shed in stool.
Japonicum in an unstained wet mansoji of stool. Schistosoma intercalatum is related to S. The eggs are similar to S. Schistosoma mekongi is a species similar to S.
They also contain a small, inconspicuous spine and are shed in stool.
Note the inconspicuous spine red arrow. Eggs of Schistosoma spp. Higher magnification of the specimen in Figure A. Adults of Schistosoma mansoni. Unlike the flukes, adult schistosomes have the sexes separate, with the female residing in a gynecophoral canal within the male. Male worms are robust, tuberculate and measure mm in length.
Females are longer mm in length and slender. Cross-sections of human tissues with Schistosoma spp. Intermediate hosts for Schistosoma spp. The intermediate hosts of Schistosoma spp. Eggs are shed from the human host in feces or urine. Under optimal conditions in the environment, the eggs hatch and release miracidia, which swim and penetrate specific snail intermediate hosts.
The stages in the snail include two generations of sporocysts and the production of cercariae.
Upon release from the snail, the infective cercariae swim and penetrate the skin of the human host, where maturation of the worms continues. Laboratory Diagnosis Laboratory Diagnosis Microscopic identification of eggs in stool or urine is the most practical method for diagnosis.
Antibody detection Antibody detection can be useful to indicate schistosome infection in patients who have traveled in schistosomiasis endemic areas and in whom eggs cannot be demonstrated in fecal or urine specimens.
Treatment Information Treatment Information Treatment information for manaoni can be found at: Get Email Updates To receive email updates about this page, enter your email address: December 18, Page last updated: December 18, Content source: Linking to a non-federal site does not constitute an endorsement by HHS, CDC or any of its employees of the sponsors or the information and products presented on the site.