E. histolytica zoology parasites, Lecture notes of Zoology

Download E. histolytica zoology parasites and more Lecture notes Zoology in PDF only on Docsity! Entamoeba histolytica • Disease – Intestinal amoebiasis, amoebic dysentery. • Geographical distribution – Cosmopolitan, mainly in tropical and subtropical areas. • Morphology 1- Trophozoite: – It is 25-20μm, in large intestine.μm, in large intestine.m, in large intestine. – Ectoplasm: well defined hyaline layer. – Endoplasm: granular cytoplasm – Nucleus: spherical, central, small karyosome and fine peripheral chromatin dots. Trophozoite acts as active motile feeding reproducing stage. - Habitat: The parasite lives in the large intestinal lumen mainly caecum and may invade other tissues, reaching the circulation leading to extra-intestinal lesions. - Infective stage: 4 nucleated cyst in contaminated food. - Mode of infection: Ingestion of infective stage (cyst). Life cycle • Pathology 1. Intestinal amoebiasis:- • Invasion of the intestinal wall leads to formation of several flask-shaped ulcers in the colon as primary lesions. 1. Extraintestinal amoebiasis: • The lesions are secondary to the primary large intestinal lesions and may result in hepatic, pulmonary or cerebral, renal....ect amoebic abscess. • Diagnosis 1) Diagnosis of intestinal amoebiasis: a) Stool examination: cyst and trophozoite are found in stool. b) Culture: Culture on specific media may be used to increase the number of positive cases. 2) Diagnosis of extra-intestinal amoebiasis: a) Serology: More than 90% of patients have positive serologic titers. b) Radiology: May be suggestive specially in hepatic amoebic abscess. c) Detecting the parasite: Aspiration of the lesion in selected cases may be of help. • Control 1) Food sanitation, sanitary waste disposal & safe water supply. 2) Treatment of infected cases.. 3) Flies control. 4) Food handlers examination. 5) Health education. Entamoeba coli life cycle stages 2. CYST - encystment is similar to that of E. histolytica - immature cysts are rare in fecal smears - mature cyst is large, 10 to 33 m, has 8 nuclei - cyst is released in the feces into the external environment - importance of human infection? Entamoeba coli life cycle Nultiplies by binary fission ‘Trophezoite in lumen of colon MAN Rncyata Trapbozoite and cysts in Dinintegrates EXTERNAL ENVIRONMENT Immature cyst amature cyst 14 nucledl Qoudeid