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Introduction to Parasites

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  1. Introduction to Parasites Classification, General Characteristics of parasites and Medically important Parasites

  2. Parasites Endoparasite Ectoparasite Protozoa Metazoa Arthropods

  3. Classification of Protozoa

  4. Classification of Metazoa

  5. The most common parasitic infection

  6. Medically important Protozoan Diseases

  7. Intestinal • Amebiasis .............................. Entamoebahistolytica • Giardiasis ...............................Giardia lamblia • Balantidiasis.......................... Balantidium coli • Crytosporidosis ..................... Cryptosporidium parvum • Cyclosporiasis …………………….. Cyclosporacayetanensis • Genitourinary tract • Trichomoniasis ....................... Trichomonasvaginalis • Blood and Tissue • Malaria ................................... Plasmodium spp • Meningoencephalitis ............. Naegleriafowleri • Toxoplasmosis ........................ Toxoplasma gondii……….. (Eye) • Cardiovascular system • African Sleeping Sickness ...... Trypanosomabrucei…….. (CNS) • ChagasDisease ...................... Trypanosomacruzi • Skin and mucous membrane • Visceral leishmaniasis( Kala-azar) ... Leishmaniadonovani • Cutaneous leishmaniasis .......... Leishmaniatopica/braziliensis

  8. Medically important Protozoan Diseases • Gastrointestinal infections • Amebiasis • Observed ingegsted RBCs indicate pathogenic E. histolytica • Giardiasis • By Giardia lamblia, an intestinal flagellate • A diarrheal disease • + Person to person by soiled hands to mouth • Balantidiasis • By Balantidium coli , the only ciliated protozoan that causes human infection • Crytosporidosis • By Cryptosporidium parvum • A diarrheal disease • + Person to person + animal to person • Cyclosporiasis • By Cyclosporacayetanensis • Transmission is Primarily waterborne but + ingestion of contaminated raspberries, basil and lettuce

  9. Medically important Protozoan Diseases • Genitourinary tract infections • Trichomoniasis • By Trichomonasvaginalis • A flagellate that has no cyst form • Sexually transmitted disease, STD • Symptomatic in females and Asymptomatic in males • Saline wet mount examination of vaginal or urethral discharge – motile trophozites

  10. Medically important Protozoan Diseases • Protozoal infections of the eyes • Amebic Eye infection • Toxoplasmosis • By Toxoplasma gondii, intracellular sporozoan • Ingestion of raw or undercooked meat containing the cyst • Typically diagnosed by Immuno-Diagnostic Procedures, IDPs • Stained biopsy

  11. Medically important Protozoan Diseases • Cardiovascular system infections • African Sleeping Sickness (African trypanosomiasis) • By Trypanosomabrucei, Hemoflagellates • Transmitted by Tsetse flies • Diagnosed by observing trypomastigotes in blood, lymph node aspirates or CSF • Chagas Disease (American trypanosomiasis) • By Trypanosomacruzi, Hemoflagellates • Transmitted by infected reduviid bugs, or blood transfusion • Diagnosed by observing trypomastigotes in blood, lymph node biopsies or tissue

  12. Medically important Protozoan Diseases • Skin and mucous membrane • Visceral leishmaniasis( Kala-azar) • Leishmaniadonovani • Cutaneous leishmaniasis • Leishmaniatopica/braziliensis • Leishmaniaspp. • Tissue flagellates • Usually transmitted by sandfly • Many animal reservoirs • Diagnosis usually by microscopic identification of non-motile amastigote form inside macrophages • Some diagnosis by IPDs

  13. Medically important Protozoan Diseases • Blood and Tissue • Malaria • Causing 1.5 million deaths annually • Plasmodium spp: • P. vivax, P. falciparum, P. ovale, P. malariae • Intraerythrocyticsporozoan parasites • Transmitted by the bite of infected Anopheles mosquitoes • Mosquitoes are definitive hosts, and humans are intermediate hosts • Malaria is diagnosed by observing trophozoites, sporozoites, or gametocytes in stained blood smears

  14. Medically important Arthropods

  15. Arthropod Involvement in Human Diseases

  16. Arthropods that serve as vectors of human infectious diseases

  17. laboratory Methods For Parasites In stool • Faecal specimens may contain several stages of Parasites • The stages of protozoa found in stools are trophozoites and cysts • The stages of helminthes usually found in stools are eggs, larvae, adult’s worms or segments of worms

  18. Intestinal protozoal infections diagnosed by examining stool specimens Observation required for Diagnosis • Trophozites (amebas) and/or cyst • Trophozites and/or cyst • Oocycts • Oocycts • Trophozites and/or cyst Infection • Amebiasis • Balantiadiasis • Cryptosporidiosis • Cyclosporiasis • Giardiasis

  19. Examples of protozoal infections diagnosed by examining stained blood smears Infection • African trypanosomiasis • American trypanosomiasis • Babesiosis • Malaria Observation required for Diagnosis • Extracellular trypomastigotes • Extracellular trypomastigotes • Intraerythrocytic protozoa • Intraerythrocytic protozoa

  20. Laboratory Methods For Parasites diagnosis • Collection of faecal specimens: • The container should be free from antiseptics and disinfectants • Add some form of preservative • Microscopic Examination of Wet Mount • The basic types of wet mount that should be used for each faecal examination are saline, iodine, and buffered methylene blue

  21. General aspects about parasite treatment and control • Importance of understanding parasite life cycles for effective treatment and control • Life cycle involves one or more species of vector • Life cycle involves one or more intermediate hosts • Parasite has a variety of definitive hosts • Parasite has life cycle stages that are exposed to the environment • Sequence and timing of life cycle stages within a host • Location within host 

  22. General aspects about parasite treatment and control Direct life cycle • Importance in treatment/ control • Provision of sanitation and basic hygiene practices can prevent many gastrointestinal parasitic diseases • Application of life cycle knowledge • Washing fruit and vegetables in clean water can remove protozoan cysts and helminth eggs

  23. General aspects about parasite treatment and control Life cycle involves one or more species of vector • Importance in treatment/ control • Disease transmission can be controlled by targeting the vectors • Application of life cycle knowledge • Bed-nets can prevent mosquitoes transmitting malaria

  24. General aspects about parasite treatment and control Life cycle involves one or more intermediate host • Importance in treatment/ control • Disease transmission can be controlled by targeting the intermediate hosts • Application of life cycle knowledge • Drainage to remove the habitat of snail intermediate hosts of Fasciola hepatica 

  25. General aspects about parasite treatment and control Parasite has a variety of definitive hosts • Importance in treatment/ control • Reservoir hosts are a potential source of infection • Application of life cycle knowledge • Schistosomajaponicum has numerous reservoir hosts which can contaminate paddy field etc with eggs

  26. General aspects about parasite treatment and control Parasite has life cycle stages that are exposed to the environment • Importance in treatment/ control • Environmental conditions can promote or limit infection • Application of life cycle knowledge • Composting can kill the infective stages of many gastrointestinal parasites

  27. General aspects about parasite treatment and control Sequence and timing of life cycle stages within a host • Importance in treatment/ control • Optimal time for diagnosis • Application of life cycle knowledge • Mf of Wuchereriabancrofti exhibits periodicity

  28. General aspects about parasite treatment and control Location within host • Importance in treatment/ control • Optimal time for diagnosis • Application of life cycle knowledge • Cattle should be treated for warble fly infections before the larvae reach their resting site