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Schistosomiasis
Schistosomiasis is caused by parasitic worms of the genus Schistosoma. There are several species that cause distinct forms of the disease depending on the organs affected. People become infected through contact with freshwater contaminated with larvae from infected snails. Symptoms vary depending on the species and stage of infection but commonly include abdominal pain, diarrhea, blood in urine or stool. Praziquantel is the treatment used to cure all forms of the disease. Prevention relies on avoiding contact with contaminated freshwater sources.
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Schistosomiasis
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- 2. Schistosomiasis, alsocalled bilharzia or bilharziasis, snail fever, or Katayama fever. Schistosomiasis is a disease caused by parasitic worms of the Schistosoma type.
- 3. SPECIES OF SCHISTOSOMA S. japonicum- causes Asian intestinal schistosomiasis. S. mansoni- causes intestinal schistosomiasis that lodges in the blood vessels. S. haematobium- causes urinary schistosomiasis. S. intercalatum and S. mekongi
- 4. SNAIL HOSTS The differentspecies of Schistosoma have different types of snails serving as their intermediate hosts; these hosts are as follows : Biomphalaria for S. mansoni Oncomelania for S. japonicum Tricula (Neotricula aperta) for S. mekongi Bulinus for S. haematobium and S. intercalatum
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- 6. S. haematobium S. intercalatumS. mekongi
- 7. INCUBATIONPERIOD 4-6 weeksusually pass before egg production begins. Cercariae reach the portal venous system several days post-infection . Toxemic schistosomiasis may develop 6-8 weeks post infection. Urinary schistosomiasis may develop 10- 12 weeks post infection. Adult schistosomes may live 20 to 30 years.
- 8. MODE OF TRANSMISSION Eggs hatch releasing miracidia (larvae/larval stage) Miracidia penetrate snail tissues— Oncomelania hupensis (freshwater snails) Cercariae released by snail into water ang free-swimming which penetrates the skin especially in cuts or wounds.
- 9. Cercariae lose tailsduring penetration and becomes schistosomulae After circulation, the schistosomulae migrate to portal blood in liver and mature into adults.
- 10. Paired adult wormsmigrate to: Meseneteric venules of rectum (laying eggs that circulate in the liver and shed in stool) by S. japonicum and S. mansoni Venous plexuses of bladder and shed in urine by S. haematobium
- 12. SIGNSAND SYMPTOMS Symptoms varywith the species of worm and the phase of infection. Heavy infestation (many parasites) may cause fever, chills, lymph node enlargement, and liver and spleen enlargement. Initial invasion of the skin may cause itching and a rash (swimmer's itch). In this condition, the schistosome is destroyed within the skin.
- 13. Intestinal symptoms include abdominalpain and diarrhea (which may be bloody). Urinary symptoms may include frequent urination, painful urination (dysuria), and blood in the urine (hematuria).
- 14. COMPLICATIONS Gastrointestinal bleeding GI obstruction Malnutrition Schistosomalnephropathy Renal failure Pyelonephritis Hematuria
- 15. Hemospermia Squamous cell bladdercancer Sepsis (Salmonella) Pulmonary hypertension Cor pulmonale Neuroschistosomiasis - Transverse myelitis, paralysis, and cerebral microinfarcts
- 16. Infertility Severe anemia Low ̶birth-weight babies Spontaneous abortion Higher risk for ectopic pregnancies End-organ disease
- 17. Portal hypertension Obstructive uropathy Pregnancycomplications from vulvar or fallopian granuloma Carcinoma of the liver, bladder, or gallbladder
- 18. SCREENING TESTS KATO-Katz- isa laboratory method for preparing human stool samples prior to searching for parasite eggs. Urine filtration method- test for the presence of S. haematobium. Blood tests- are occasionally useful in supporting the diagnosis or assessing the severity of schistosomal infection. Rectal Mucosal Biopsy
- 19. TREATMENT AND CURE Praziquantel-used to treat all kinds of schistosoma species Steroids (Corticosteroids) are used to relieve the symptoms of acute schistosomiasis.
- 20. Schistosomaspecies infection Praziquanteldose and Duration Schistosoma mansoni,S. haematobium, S. intercalatum 40 mg/kg per day orally in two divided doses for one day S. japonicum, S. mekongi 60 mg/kg per day orally in three divided doses for one day
- 22. SIDE EFFECTS OFPRAZIQUANTEL More common Drowsiness Increased sweating General feeling of discomfort or illness Nausea or vomiting Less common Hives or Urticaria
- 23. PREVENTION Avoid swimming orwading in freshwater especially those with open wounds or cuts Drink safe water Always boil or filter water even for used for bathing
- 24. CONTROL Mass treatment ofentire communities and targeted treatment of school-age Improved sanitation could reduce or eliminate transmission of this disease