Transcript 031ed86aee2fd80

(Leishmania parasites)
By
Dr. Rasha Soliman
Associate Prof. of Parasitology
Learning outcomes
• 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.
12
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).
THANK YOU