Urinary Schistosomiasis

Urinary Schistosomiasis

• 1.
  URINARY SCHISTOSOMIASIS
• 2.
  INTRODUCTION • Schistosomiasis isa parasitic disease caused by flukes (trematodes) of the genus Schistosoma. • Trematodes, or flatworms, are a group of morphologically and biologically heterogeneous parasitic helminths that belong to the phylum Platyhelminthes. Human infection with trematodes occurs in many geographic areas and can cause considerable morbidity and mortality. • Trematodes share some common morphologic features, including macroscopic size (from 1cm to several cm); dorsoventral, flattened, bilaterally symmetric bodies (adult worms); and the prominence of 2 suckers. Except for the schistosomes, all trematodes that parasitize humans are hermaphroditic. • Life cycle of trematodes involves a definitive host (mammalian/human), in which adult worms initiate sexual reproduction, and an intermediate host (snails, fish), in which asexual multiplication of the larval forms occurs.
• 3.
  ETIOLOGY • S. haematobium(vesical venous plexus) • Africa, Middle east, India,Turkey • Others (intestinal schistosomiasis): S. mansoni, S. japonicum, S. mekongi, and S. intercalatum
• 4.
  Life cycle
• 5.
  BLOOD FLUKES • Humanschistosomiasis is caused by five species of this parasitic trematode belonging to the subclass Digenea: the intestinal species Schistosoma mansoni, S. japonicum, S. mekongi, and S. intercalatum and the urinary species S. haematobium. Infection may cause considerable morbidity in the intestines, liver, and urinary tract, and a proportion of affected individuals die.
• 6.
  EPIDEMIOLOGY • The distributionof schistosome infection and related disease syndromes in human populations is dependent on both parasite and host factors. In endemic areas, the rate of yearly onset of new infection, or incidence, is low. Prevalence, on the other hand, starts to be appreciable by the age of 3 to 4 years and builds to a maximum that varies by endemic region (up to 100%) in the 15- to 20-year age group. Prevalence then stabilizes or decreases slightly in older age groups (>40 years).
• 7.
  PATHOGENESIS AND IMMUNITY •Granuloma formation at the lower end of the ureters obstructs urinary flow, with subsequent development of hydroureter and hydronephrosis. Similar lesions in the urinary bladder cause the protrusion of papillomatous structures into its cavity; these may ulcerate and/or bleed.The chronic stage of infection is associated with scarring and deposition of calcium in the bladder wall.
• 8.
  CLINICAL FEATURES • Upto 80% of children infected with S. haematobium have dysuria, frequency, and hematuria (painless), which may be terminal. • Cercarial dermatitis (swimmers itch / kabure itch) • Katayama syndrome (3-6 weeks after penetration of cercarie): fever, cough, headache, sweating, abd pain, tender, hepatosplenomegaly • Urine examination reveals blood and albumin as well as an unusually high frequency of bacterial urinary tract infection.These manifestations correlate with intense infection, the presence of urinary bladder granulomas, and subsequent ulceration. • Along with the local effects of granuloma formation in the urinary bladder, bladder polyps/ulcers, obstruction of the lower end of the ureters results in hydroureter and hydronephrosis, which can be seen in 25~50% of infected children.
• 9.
  DIAGNOSIS • Falcon assayscreening test/enzyme-linked immunosorbent assay (FAST-ELISA) • Confirmatory enzyme-linked immuno- electrotransfer blot (EITB). Both tests are highly sensitive and ~96% specific. • Examination of stool or/ urine for ova/egg may yield positive results. • Urine examination reveals blood and albumin (severe UTI): hematuria, proteinuria
• 10.
  TREATMENT • In severeacute schistosomiasis, an acute-care setting is necessary, with supportive measures and consideration of glucocorticoid treatment. • Once the acute critical phase is over, specific chemotherapy is indicated. • Antihelminthics (Praziquantel) is administered orally as 40 or/ 60 mg/kg, 2 or 3 times/day • Additional management modalities are needed for individuals with other manifestations, such as hepatocellular failure or recurrent hematemesis. The use of these interventions is guided by general medical & surgical principles.
• 11.
  PREVENTION AND CONTROL •For travelers, avoid contact with all freshwater bodies, irrespective of speed of water flow or unsubstantiated claims of safety. • People of endemic regions should use freshwater bodies for sanitary, domestic, recreational, and agricultural purposes. • Current recommendations to countries endemic for schistosomiasis emphasize the use of multiple approaches. • The ultimate goal of research on prevention and control is the development of a vaccine. Although there are a few promising leads, this goal is probably not within reach during the next decade or so.