Leishmaniasis PDF

# Leishmaniasis ## Kariuki Njaanake, PhD ### **Genus *Leishmania*** - In the order *Kinetoplastida* - Over 20 pathogenic species of the *Leishmania* - *Leishmania* are parasites of humans and other mammals (especially dogs and rodents) - *Leishmania* are cyclically transmitted by *Phlebotomus*...

# Leishmaniasis ## Kariuki Njaanake, PhD ### **Genus *Leishmania*** - In the order *Kinetoplastida* - Over 20 pathogenic species of the *Leishmania* - *Leishmania* are parasites of humans and other mammals (especially dogs and rodents) - *Leishmania* are cyclically transmitted by *Phlebotomus* and *Lutzomyia*. The image shows a world map with areas where *Leishmania* is found in red. ### **Old World Leishmania *spp*.** | Species Complex | Disease | Distribution | |---|---|---| | *L. major* | "wet" cutaneous | Widely distributed in rural areas of Asia and Africa | | *L. tropica* | "dry" cutaneous| Not common, but it is found in urban areas of Europe, Asia and North Africa | | *L. aethiopica* | Cutaneous (often diffuse) | Ethiopia and Kenya | | *L. donovani donovani* | visceral (Kala Azar) | Africa and Asia | | *L. donovani archibaldi* | Visceral | Kenya | | *L. donovani sinensis* | Visceral | China | | *L. donovani infantum* | Infantile visceral | Mediterranean region and East Africa | ### **New World Leishmania *spp*.** | Species Complex | Disease | Distribution | |---|---|---| | *L. donovani chagasi* | Visceral | South America | | *L. braziliensis braziliensis* | Muco-cutaneous (Espundia)| South America (especially Brazil) | | *L. braziliensis guyanensis* | Cutaneous | South America | | *L. braziliensis panamensis* | Muco-cutaneous | South and Central America | | *L. mexicana mexicana* | Cutaneous | South and Central America | | *L. mexicana amazonensis* | Cutaneous | South and Central America | | *L. mexicana pifanoi* | Cutaneous| South and Central America | | *L. peruviana* | Cutaneous | South America, mainly Andean region | ### **Morphology** - In the insect/ culture media the parasites assume the promastigote form. - Contain a centrally located nucleus, a rod-shaped kinetoplast (specialised portion of a highly extended, convoluted mitochondrion containing DNA) - A basal body (from which the flagellum arises) ### **Mammalian hosts** - Parasites occur in amastigote form only. - Small, ovoid or round intracellular bodies (*Leishman-Donovan bodies*) measuring about 2 to 5 µm in diameter. - Reside in macrophages and certain leucocytes in spleen, liver, bone marrow, lymph nodes, intestinal mucosa and certain other tissues. The image shows a *Leishmania* amastigote form. The image shows a diagram of the life cycle of *Leishmania donovani*. ### **Leishmaniasis** There are three distinct clinical presentations of leishmaniasis: #### **a) Cutaneous leishmaniasis** - Old World cutaneous leishmaniasis - New World cutaneous leishmaniasis The image shows skin lesions from *Leishmania tropica*, *L. major*, *L. aethiopica*. #### **b) Mucocutaneous leishmaniasis** (*Espundia, chiclero ulcer or Uta*) - *L. braziliensis* - Most severe and destructive - Cause large ulcers - Parasites migrate to mucocutaneous tissues - nasopharynx, palate, etc. The image shows mucocutaneous lesions caused by *L. braziliensis*. #### **c) Visceral leishmaniasis (Kala Azar)** - The image shows a world map, with areas where kala-azar is found in green and red. - Most serious and often fatal form of human leishmaniasis - Caused by *L. donovani* and its subspecies - Common symptoms are irregular bouts of fever, malaise, weight loss, anorexia accompanied by anaemia, splenomegaly and hepatomegaly, skin darkening - May be classified as: * **Endemic visceral leishmaniasis** - This especially affects children aged between 1 and 4 years in the Mediterranean area, South-West Asia, China and Latin America * **Sporadic visceral leishmaniasis** - This affects non-indigenous people entering an epidemic area. Has more acute course * **Epidemic Visceral leishmaniasis** - All ages are susceptible except those old enough to have been infected during a previous epidemic. - In East Africa and India, the peak age is 5 to 9 years. - Normally more boys than girls are affected - Easily misdiagnosed for malaria - **Post-Kala azar Dermal Leishmaniasis (PKDL)** - Characteristically follows visceral leishmaniasis - Patient develops some immunity which causes PKDL - PKDL may also be related to a previous infection. The image shows a patient with PKDL lesions. - **Factors of outcome of infection with *Leishmania spp*.** - Parasite strain - Size of inoculum - Site of inoculation - Host genetics - Acquired immunity (?HIV) - Nutritional state ### **Diagnosis** - Identification of *Leishmania spp*. from: - skin lesions (cutaneous forms) - blood, bone marrow, lymph nodes or spleen (kala-azar) - May-Grunewald-Giemsa stain: parasites are intracellular and seen within histiocytes - Culture methods The image shows the different methods for diagnosing kala azar. ### **Treatment** - Pentavalent antimony (Sodium stibogluconate/ meglumine antimoniate) - Liposomal Amphotericin B (VL) - Fluconazole - Miltefosine (CL + VL) - Topical paromomycin & methylbenzethonium - Local heat therapy or cryotherapy ### **Control** - Avoid sandfly bites - Control of sandfly vector - Control of animal reservoir - Treatment of infected individuals