Leishmania
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Leishmania is a genus of protozoan parasites that causes leishmaniasis, a vector-borne disease spread by sandfly bites. It exists in two forms: amastigotes within host cells and promastigotes in sandflies. The disease manifests as visceral, cutaneous, or mucocutaneous leishmaniasis depending on the infected tissues. Visceral leishmaniasis affects internal organs while cutaneous primarily affects the skin. Diagnosis involves detecting the parasites microscopically or through culture. Treatment involves pentavalent antimonials, amphotericin B, or miltefosine. Control relies on reducing sandfly and reservoir populations through insecticides and treating
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Leishmania
- 3. INTRODUCTION Leishmania: • Is a genus of trypanosomatid protozoa, which causes a fatal vector-borne parasitic disease called Leishmaniasis. It is spread by the bite of sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. • Leishmaniasis: • is the second-largest parasitic killer in the world (after malaria) and is endemic in many parts of Africa, Asia and South America.
- 5. IMPORTANT SPECIES • • • • L. donovani L. tropica L. mexicana L. braziliensis • L.major • L.guyanensis • L.lainsoni, etc
- 6. HABITAT (L.donovani) Are essentially the parasites of visceral organs. Promastigote forms found in sand fly and in culture. Amastigote forms found in man in reticuloendothelial cells of spleen, bone marrow, liver, intestinal mucosa, mesentric lymph node.
- 7. MORPHOLOGY (same in all species) • The parasite exists in 2 forms;1. Amastigotes – aflagellar stage 2. Promastigotesflagellar stage
- 8. Morphological Differences Amastigotes Promastigotes • Aflagellar stage • Flagellar stage • Occurs in the vertebrate host • Occurs in the sand fly • divides by binary fission at 37oC. • divides by binary fission at 27oC. • There are round or oval ;2-4µm along longitudinal axis. • They are spindle shaped ;15-20 µm in Nucleus relatively larger and situated centrally. • • length & 1-2µm in width. Nucleus smaller and situated in the middle of the cell or along the side of cell-wall.
- 10. Life cycle of other species of Leishmania are similar to L.donovani except that In L.tropica • amastigotes reside in the large mononuclear cells of the skin In L.mexicana • Amastigotes found in reticuloendothelial cells and lymphatic tissues of skin In L.braziliensis • amastigotes are found in reticuloendothelial cells and lymphatic tissues of skin and mucus membrane
- 11. MODE OF TRAMSMISSION (L.donovani) 1. Mainly by the bite of sand fly (vector) Phlebotomus argentipus 2. LesS frequently by: blood transfusion, congenital infection, accidental inoculation of cultured promastigotes in the lab. Workers. sexual intercourse. Males are affected more (due to increased exposure to sand flies through the occupation and leisure activities).
- 12. RESERVOIR (L.donovani) • Human:- in Indian subcontinent • Rodents:- in Africa • Foxes:- in Brazil and Central Asia • Dogs :- In China
- 13. VECTOR • Phlebotomas (Sand fly) • Lutzomyia
- 14. CLINICAL MANIFESTATIONS 1. Fever 2. Spleen enlargement 3. Lymphadenopathy 4. Darkening of the skin (KALA AZAR, MEANING “BLACK FEVER) Complications:- pneumonia, TB, dysentery, uncontrolled haemorrhage Prognosis:- With an early treatment, cure rate >90% If not treated, death occurs within 2 years.
- 15. TYPES OF LEISHMANIASIS Leishmaniasis is divided into clinical syndromes according to what part of the body is affected most. Visceral Leishmaniasis(VL) Cutaneous Leishmaniasis(CL) Mucocutaneous leishmaniasis(MCL)
- 16. Continued.... 1. Visceral Leishmaniasis (VL) or Kala-azar caused by L.donovani part of the body affected most is internal organs Spleenomegaly
- 17. Continued.... 2. Cutaneous Leishmaniasis(CL) ( most common type) a) Old world CL:- caused by L.tropica, L. aethiopica b) New world CL:- caused by L.mexicana, L.braziliensis, L.g uyanensis c) Dermal leishmanoid or Post kala-azar dermal leishmaniasis(PKDL):- caused by L.donovani Part of the body most affected is skin
- 18. ....continued 3. Mucocutaneous leishmaniasis(MCL) Caused by L. braziliensis and occasionally by L.panamensis Part of the body affected most is skin and mucous membrane of nose and pharynx
- 19. SYNONYMS OF LEISHMANIASIS Visceral leishmaniasis Cutaneous leishmaniasis Mucocutaneous Leishmaniasis Kala-azar, Aleppo boil, Breda's disease Black fever Baghdad boil, bosch yaws, Dum-Dum fever, Delhi boil, bush yaws Sahib’s disease Kandahar sore, forest yaws Kala Dukh Lahore sore, White leprosy Oriental sore,
- 20. LABORATORY DIAGNOSIS Direct Evidences Indirect evidences Other methods Blood count Animal inoculation Serum Tests Leishmanin or Montenegro Test Thick film method Blood culture Adler’s test Biopsy
- 21. Direct Evidences (contd......) 1. Peripheral blood by thick film method.(Amastigote form) Amastigotes in a macrophage
- 22. Direct Evidences (contd......) 2. Blood culture in N.N.N. Medium. (Promastigote form) Promastigote from culture in NNN medium
- 23. Direct Evidences (....contd) 3. Biopsy material obtained • • • by lymph node puncture, sternal or iliac crest puncture(marrow) and spleen puncture(spleen pulp) Amastigote form in a stained smear Promastigote in culture in NNN medium Amastigotes of L. donovani. Splenic aspirate.
- 24. PREVENTION AND CONTROL Reduction of Reduction of sand fly population reservoir by killing all the infected dogs in the cases of zoonotic kala-azar. by insecticides mainly DDT, dieldrin, malathion PREVENTION AND CONTROL Education in the community Prevention of exposure to sand fly About the causes and modes of transmission of leishmaniasis. using insect repellent, bed nets and window mess as needed. There are No Vaccines to prevent leishmaniasis.
- 26. TREATMENT Sodium stibogluconate solution Inhibits glycolytic enzymes and fatty acid oxidation Amphotericin B Drugs Binds with ergosterol leading to the altered permeability to cations, water, glucose and affect membrane-bound enzymes. Pentamidine Inhibits DHFR and interferes with aerobic glycolysis in protozoa, also inhibits protein synthesis Miltefosine Effects cell-signaling pathways and synthesis of the cell-membrane Interferon macrophage activation
- 27. TREATMENT (....contd) treatment of secondary microbial infections Specific therapy supplemented with high-calorie-high protein diet Blood transfusion in severe anaemia