(Leishmania parasites) Leishmaniasis (Leishmania parasites) By Dr. Rasha Soliman Associate Prof. of Parasitology

Learning outcomes 7- Disease Transmission. By the end of the lecture, you should be able to: 1- Define Leishmaniasis & Mention systematic position of Leishmania spp. 2- Mention geographic distribution of Leishmaniasis. 3- Mention vector and reservoir host of Leishmania. 4- Describe Forms and morphology of Leishmania. 5- Habitat of Leishmania in human and sand fly. 6- Explain life cycle of Leishmania spp. 7- Disease Transmission. 8- Mention pathology and clinical features of Cutaneous and Visceral Leishmaniasis. 9- Diagnose Leishmaniasis.

Suggested Reading http://www.dpd.cdc.gov/dpdx/HTML/Leishmaniasis.htm http://en.wikipedia.org/wiki/Leishmaniasis Chiodini, P.L.; Moody, A.H. and Manser, D.W. (2001): Atlas of Medical Helminthology and Protozoology. 4th ed. Churchill Livingstone, P. 71.

What is Leishmaniasis? Leishmaniasis is a disease caused by protozoan parasites that belong to the genus Leishmania. Disease is transmitted by the bite of certain species of sand fly.

Systematic position of Leishmania spp. Phylum: Euglenozoa Class: Kinetoplastidea Genus: Leishmania (L.) From genus Leishmania about 21 species infect human. 3 species are the most important: 1- L. donovani (Visceral Leishmaniasis “Kala azar”). 2- L. Tropica (Cutaneous Leishmaniasis “oriental sore”). 3- L. braziliensis (Muco-cutaneous Leishmaniasis “Espundia”)

Geographical distribution Leishmaniasis is found in parts of about 88 countries.  Approximately 350 million people live in these areas. Most of the affected countries are in the tropics and subtropics.  More than 90 percent of the world's cases of visceral leishmaniasis are in India, Bangladesh, Nepal, Sudan, and Brazil.

Geographical distribution….cont. Visceral Leishmaniasis Cutaneous Leishmaniasis

Vector of Leishmaniasis Leishmania is transmitted by certain species of sand fly, including flies in the genus Lutzomyia and Phlebotomus.

Forms of Leishmania RECs and macrophages Reservoir host

Life Cycle of Leishmania spp Leishmaniasis is transmitted by the bite of infected female phlebotomine sandflies. The sandflies inject the infective stage (i.e., promastigotes) from their proboscis during blood meals (1) . Promastigotes that reach the puncture wound are phagocytized by macrophages (2) and other types of mononuclear phagocytic cells. Progmastigotes transform in these cells into the tissue stage of the parasite (i.e., amastigotes) (3) , which multiply by simple division and proceed to infect other mononuclear phagocytic cells (4). Parasite, host, and other factors affect whether the infection becomes symptomatic and whether cutaneous or visceral leishmaniasis results. Sandflies become infected by ingesting infected cells during blood meals(5,6) . In sandflies, amastigotes transform into promastigotes, develop in the gut (7) (in the hindgut for leishmanial organisms in the Viannia subgenus; in the midgut for organisms in the Leishmania subgenus), and migrate to the proboscis (8).

Life Cycle of Leishmania spp

Life cycle……………cont.

Disease Transmission 1- Through the bite of infected sand fly. 2- By direct contact with infected material from the lesion of an infected person.

Clinical Features Human leishmanial infections can result in 3 main forms of disease: cutaneous leishmaniasis (oriental sore), visceral leishmaniasis (kala-azar), Mucocutaneous Leishmaniasis (Espundia). The factors determining the form of disease include: leishmanial species, geographic location, immune response of the host. 

Cutaneous leishmaniasis Cutaneous leishmaniasis is characterized by: 1- one or more cutaneous lesions on areas where sandflies have fed. 2- Persons who have cutaneous leishmaniasis have one or more sores on their skin. 3- The sores can change in size and appearance over time. 4- They often end up looking somewhat like a volcano, with a raised edge and central crater. 5- A scab covers some sores.  6- The sores can be painless or painful.

Cutaneous leishmaniasis …cont.

Cutaneous leishmaniasis …cont.

Visceral Leishmaniasis Persons who have visceral leishmaniasis usually have: 1- Fever. 2- Weight loss. 3- Enlarged spleen and liver (usually the spleen is bigger than the liver).  4- Low blood counts, including a low red blood cell count (anemia), low white blood cell count (leukopenia), and low platelet count.

Visceral Leishmaniasis ….. Cont.

Diagnosis of Leishmaniasis Clinically: 1- Fever 2- Enlargement of liver and spleen. 3- Anaemia & leukopenia. 4- By the picture of sore.

Laboratory Diagnosis Giemsa stained slides of the tissue used to detect the parasite (amastigote form).

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