Parasitic-protozoa-1 - infected person it sucks up the...

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Parasitic protozoa Parasitic protozoa Entamoeba histolytica is one of a number of species of small amoebae which live in the alimentary canal of humans. These are usually harmless protozoa, feeding on bacteria and particles in the intestine. In certain conditions, entamoeba invades the wall of the intestine or rectum causing ulceration and bleeding, with pain, vomiting and diarrhoea, symptoms of amoebic dysentery. The faeces of infected people contain resistant forms (cysts) of entamoeba. Conditions of poor sanitation and hygiene, therefore, favour the spread of the disease. Trypanosomes are flagellate protozoa which live in the blood stream. There are several different species of trypanosome and they cause diseases such as sleeping sickness , leishmaniasis and Chaga's disease and, in cattle, nagana . The sleeping sickness and nagana parasites are transmitted by the bite of the tsetse fly . This insect has tubular mouthparts, like the mosquito, and these pierce the skin to suck blood from a capillary. If the tetse fly bites an
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Unformatted text preview: infected person, it sucks up the trypanosomes with the blood. The trypanosomes multiply in the body of the tsetse fly and invade the salivary glands. When the fly bites a healthy person, it injects saliva, which contains the trypanosomes. The prevalence of tsetse flies in some areas makes it impossible to raise cattle because of the high incidence of nagana. The main methods of control involve attempts to reduce the population of tsetse flies. This is done by using insecticides or by changing or removing the vegetation from the areas where the tsetse flies breed. These methods are only partially successful; spraying from the air, for example, is ineffective if the flies are resting on the underside of leaves. vacuole ectoplasm nucleus endoplasm 15µ Entamoeba histolytica red cell nucleus flagellum new flagellum forming Trypanosomes in the blood Trypanosome reproducing by binary fission © D.G. Mackean...
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This note was uploaded on 11/29/2011 for the course BIO 218 taught by Professor Young during the Fall '11 term at BYU.

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