Parasitology Week 9 PDF

9 TREMATODES BLOOD FLUKES SCHISTOSOMES formerly called Bilharzia FEMALE long and slender with body circular in section MALE flattened behind ventral sucker cylindrical and incurved ventrally to form gynecophoral canal Infective Stage: Forkedtail Cercaria (nocturnal activity) Mode of Transmission: Sk...

9 TREMATODES BLOOD FLUKES SCHISTOSOMES formerly called Bilharzia FEMALE long and slender with body circular in section MALE flattened behind ventral sucker cylindrical and incurved ventrally to form gynecophoral canal Infective Stage: Forkedtail Cercaria (nocturnal activity) Mode of Transmission: Skin Penetration Schistosomule: cercaria minus tail; remains in subcutaneous tissue for 2 days LABORATORY DIAGNOSIS 1. Stool exam (DFS, Kato Katz, FEACT) S. japonicum S. mansoni 2. Urine analysis 24-hour unpreserved urine (centrifugation) for S. haematobium 3. Faust and MAlONey’s Egg Hatching Technique 4. Circumoval Precipitin Test of Oliver and Gonzales confirmatory test for Schistosomiasis REAGENT: Lyophilized S. japonicum eggs from a rabbit (reservoir host) Specimen: Serum Principle: Detection of antibodies that react with eggs Positive result: Bleb Formation 4. Antibody testing: Increased IgE, IgG4 (ELISA) 5. Antigen detection: Circulating Cathodic Antigen (urine) Circulating Anodic Antigen (serum) TREATMENT Praziquantel (2-3 doses in a single day) Infection with S. mansoni may require a larger dose than that for the other species metrifonate (Bilarcil) alternative treatment for S. haematobium organophosphorus compound given once every other week in a total of three doses Schistosoma japonicum Common Name: Oriental Blood Fluke Causes Oriental Schistosomiasis or Katayama’s Disease Habitat: Superior Mesenteric Vein in the Small Intestine host: Ih: Snail (Oncomelania hupensis quadrasi) rh: Dogs, Cats, Carabaos, other mammals fh: Man mode of transmission: Skin Penetration Allergic Reaction Swimmer’s Itch Egg: Unoperculated embryonated (mature) Smallest egg among blood flukes With a small knob-like or smalllateral spine (recurved hook on one side) pathogeneis: Chronic infection: hepatic (most serious) and pulmonary cirrhosis CNS involvement may occur Secondary bacterial infection with Salmonella Colorectal and liver carcinoma Schistosoma mansoni Common Name: Manson’s Blood Fluke Smallest ADULT Blood Fluke Causes Intestinal Bilharziasis Habitat: Inferior Mesenteric Vein of the Colon and the Rectum host: Ih: Snail (Biomphalaria spp.) rh: Nonhuman primates fh: Man infective stage: Cercaria (Forked-tail cercaria) mode of transmission: Skin Penetration Allergic Reaction Swimmer’s Itch Egg: Unoperculated embryonated (mature) With prominent lateral spine Schistosoma haematobium Common Name: Vesical Blood Fluke Causes Urinary Bilharziasis/ Urinary Schistosomiasis (Bloody Urine), Egyptian Hematuria Habitat: Vesical/Uterine Plexus near the Urinary Bladder host: Ih: Snail (Bulinus spp.) rh: None fh: man infective stage: Cercaria (Forked-tail cercaria) mode of transmission: Skin Penetration Allergic Reaction Swimmer’s Itch Egg: Unoperculated embryonated (mature) With prominent terminal spine laboratory diagnosis: 24-hour unpreserved urine sample Optimize recovery in urine: between noon and 2 PM Pathogenesis: 24-hour unpreserved urine sample Chronic infections: Bladder Carcinoma, Obstructive Uropathies, Granuloma/fibrous damage in organs Schistosoma mekongi Egg: resembles egg of S. japonicum but smaller Adult: located in the venules of small intestine Schistosoma malayensis Found in peninsular Malaysia also resembles S. japonicum Nanophyetus salmincola Philophthalmus Acanthoparyphium Alaria Gymnophalloides causes “salmon poisoning” a fatal diseases of dogs, wolves, and foxes. it harbors the rickettsia “Neorickettsia heminthoeca” “eyeflukes” intestinal parasite of ducks acquired through ingestion of frogs/infected meat parasite of shore birds Metorchis conjuctus parasite of sled dogs Watsonius watsoni trematode of monkeys Gastrodiscoides hominis only fluke inhabiting the large intestine; eggs and life cycle similar to F. buski. Adults are pyriform shaped and have conical anterior portion.