Blood and Tissue Flagellates (Hemoflagellates)

Blood and Tissue Flagellates (Hemoflagellates) Blood and Tissue Flagellates (Hemoflagellates): Family Trypanosomatidae (class Kinetoplastea): Three (four) main features of this parasites: • Nucleus • Kinetoplast • Cell wall • Flagellum (not always) Kinetoplast: • A unique form of mitochondrial DNA (A dense mass of mitochondrial DNA) • The kinetoplast DNA is composed of several thousand circular DNA molecules linked together in a catenated network Parasite forms and Morphology They are pleomorphic at various life-cycle stages. Four forms of parasites can be seen: 1) Amastigote (Intracellular form in Human) 2) Promastigote 3) Epimastigotes 4) Trypomastigote Extracellular forms 1) Amastigote (Intracellular form) = Leishman body: • A developmental stage in trypanosomes and Leishmania • In the humans’ cells (inside macrophages), the parasite is found mainly as a amastigote form • Ovoid cells, Non-motile • Size: 3-5 µm length • Little internal structure can be discerned in stained preparations at the light microscope level beyond the central round or oval nucleus and adjacent but smaller round or rod-shaped kinetoplast • In amastigote the flagellum are not seen under light microscope 2) Promastigote (Leptomonad Stage): • A developmental stage in trypanosomes and Leishmania • In the sandfly host and in culture media, the parasite is found mainly as a promastigote form • Elongated (fusiform body), Motile • Size: 8-15 µm • It has no undulating membrane • The structural elements of promastigotes are the same as those described for amastigotes. The main differences from the amastigotes are that the cell body is elongated, 8-15 µm, and that the flagellum emerges from the cell body and is functional thus making these motile cells • These organisms have a central nucleus and a single anterior flagellum arising from a kinetoplast near the anterior end 3) Epimastigotes: • A developmental stage in trypanosomes • Have a kinetoplast adjacent to the nucleus • Have an undulating membrane that runs along approximately the anterior half of the organism • Divide by binary flssion in the hindgut of the triatomine bug vector 2) Trypomastigote: • A developmental stage in trypanosomes • Developmental stage of trypanosomes, usually in the vertebrate host but may be in the invertebrate. • A stage in the life cycle that is elongated with the kinetoplast posterior and distal to the nucleus. • A leaflike form with an undulating membrane and often a free flagellum. Blood and Tissue Flagellates (Hemoflagellates): Trypanosomatidae family Two important genus: 1) Leishmania species (Agents of the cutaneous, mucosal and visceral Leishmaniasis) 2) Trypanosoma species (Agents of African Trypanosomiasis and Chagas’ Disease) 1- Leishmania and Leishmaniasis Leishmania and Leishmaniasis Leishmaniasis caused by protozoan parasites Leishmania, is a disease of poverty as its victims are among the poorest According to ranking after malaria it is a second most prevalent parasitic disease Leishmaniasis has been considered a tropical affliction that constitutes one of the six entities on the list of most important diseases of World Health Organization/Tropical Disease Research (WHO/TDR) viz: • Malaria, Schistosomiasis, Filariasis, Chagas disease, Trypanosomiasis, Leishmaniasis, Leprosy, Tuberculosis African TOXONOMY Kingdom: Protista Subkingdom: Protozoa Phylum: Sarcomastigophora Subphylum: Mastigophora Class: Zoomastigophora Order: Kinetoplastida Suborder: Trypanosomatina Family: Trypanosomatidae Genus: Leishmania & Trypanosoma Genus: Leishmania  Two subgenus according to the location of parasites inside intermediate host: I. Leishmania Development in midgut and foregut of sandfly (suprapylarian) II. Viannia Development in hindgut of sandfly (periprapylarian) The enzyme aconitate hydratase is able to distinguish the subgenus Viannia from the other leishmanias Subgenus: Leishmania Both Old World and New World species Transmitted by Sandfly =  in Old World (Iran) Phlebotomus spp.  in New World (South America)  Lutzomyia spp. : Subgenus: Leishmania I. Leishmania tropica complex II. Leishmania mexicana complex III. Leishmania donovani complex I. Leishmania tropica complex  Causative agent of CL and DCL in the Old World 1. L. (Leishmania) tropica 2. L. (L.) major 3. L. (L.) aethiopica II. Leishmania mexicana complex  Causative agent of CL and MCL in the New World 1. L. (L.) mexicana 2. L. (L.) amazonensis 3. L. (L.) garnhami 4. L. (L.) pifanoi 5. L. (L.) venezuelensis III. Leishmania donovani complex  Causative agent of VL 1. L. (L.) infantum 2. L. (L.) donovani 3. L. (L.) chagasi Subgenus: Viannia Development in sandfly in hindgut, followed by migration to the midgut and foregut All in the Leishmania braziliensis complex Transmitted by:  Lutzomyia spp (Sandfly). Subgenus: Viannia Leishmania braziliensis complex  Causative agent of MCL 1. 2. 3. 4. 5. 6. 7. 8. 9. L. (Viannia) braziliensis L. (V.) colombiensis L. (V.) panamensis L. (V.) guyanensis L. (V.) peruviana L. (V.) naiffi L. (V.) equatorensis L. (V.) lainsoni L. braziliensis/L. guyanensis hybrid Leishmania and Leishmaniasis Types of disease caused by different species of Leishmania: 1) Cutaneous Leishmaniasis (CL) or Salak 2) Visceral Leishmaniasis (VL) or Kala-azar 3) Mucocutaneous Leishmaniasis (MCL) 4) Diffuse Cutaneous Leishmaniasis (DCL)