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Kingdom:
Protisata
Phylum:
Sarcomastigophora
Class:
Zoomastrgophora
Order:
Kimetplastida
Family:
Trypanosomatidae
Genus:
Leishmania
Species:
Donovani , Tropica, Mexicana,Braziliensis
(Picture courtesy of CDC)
Cutanious Leishmaniasis
Courtesy of NIH
Picture
courtesy of bugs of the web
Check
out video life cycle at WHO
Literature
Cited
The
Center for Disease Control:
CDC. June 2000. Leishmania Infection. www.cdc.gov/ncidod/dpd/parasites/leishmania/factsht_leishmania.htm.
(accessed 03/04/2003)
CDC
Fact Sheet
The
Center for Disease Control Fact Sheet on Leishmania
(http://www.cdc.gov/ncidod/dpd/parasites/leishmania/factsht_leishmania.htm)
(accessed 03/05/03)
CDC
Parasites and Health
The
Center for Disease Control Division of Parasites and Health
(http://www.dpd.cdc.gov/dpdx/HTML/Leishmaniasis.htm) (Accesesed 03/05/03)
McGill
University
McGill University. James Smith, Parisitology Leishmania.
(http://martin.parasitology.mcgill.ca/jimspage/biol/leish.htm) (accessed
03/22/03)
The
Medical Letter
The Medical Letter, A nonprofit publication on Drugs and Therapeutics.
(http://www.medletter.com) (accesed 03/27/03)
MEDLINEplus
Medical Encyclopedia
MEDLINEplus Medical Encyclopedia, A service of the US Library of Medicine
(http://www.nlm.nih.gov/medlineplus/ency/article/001386.htm) (accessed
03/24/03)
National
Institute of Health
The National Institute of Health, Dr. Martin NIAID Research on Vaccines
and Immunity
(http://www.niaid.nih.gov/newsroom/focuson/bugborne01/leish.htm) (accessed
03/21/03)
University
of East London
University of East London Life Sciences Department.
(http://homepages.uel.ac.uk/D.P.Humber/akhter/cont.htm#fly) (accessed
03/21/03)
The
World Health Organization:
WHO.May 2000 THE LEISHMANIASES
AND LEISHMANIA/HIV CO-INFECTIONS
(http://www.who.int/emc/diseases/leish/leisdis1.html)
(accessed 03/25/03)
World
Health Organization, Fact sheet on Leishmania/HIV co-fection
World Health Organization, Fact sheet on Leishmania/HIV co-fection
(http://www.who.int/inf-fs/en/fact116.html) (accessed 03/1903)
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Introduction
The
genus Leishmania is a member of the phylum Sarcomastigophora of the
kingdom protista. It is a diploid, intracellular parasite with a single
flagellate.
(Picture
courtesy of CDC)
Leishmania
is a parasite that affects vertebrates with the disease called Leishmaniasis.
It has a complex life cycle. When an infected Phlebotomid sand fly (Phlebotomus)
takes a blood meal it infects the vertebrate host with promastigote
metacyclic forms. Within a short time the promastigotes are taken up
by macrophages, the first line of defense of the immune system. The
promastigote then loses its flagella and transforms into the amastigote
form. Once internalized in a phagosome the macrophage lysosome fuses
with the phagosome to from a phagolysosome containing the parasite.
(CDC Fact Sheet)
(CDC Parasites and Health)
There
are three groups for Leishmania divided depending on their development
within the sand fly vector. These are:
· Hypopylaria -
develop in the ileum and rectal areas of the sand fly
· Peripylaria -
develops in both in the anterior ileum and in the stomach and pharynx
of the sand fly.
·Suprapylaria -
develops in the stomach and pharynx of the sand fly. (McGill University)
Leishmania can be present in the human in three different types:
Visceral Leishmaniasis
(VL) is the most severe form of the disease. It is characterized by
irregular bouts of fever, substantial weight loss, swelling of the spleen
and liver, and anemia. This form is caused by L.donovani.
Mucocutaneous Leishmaniasis
(MCL) produces lesions, which can lead to extensive and disfiguring
destruction of mucous membranes of the nose, mouth and throat cavities.
This form is caused by L. braziliensis and L. mexicana.
Cutaneous leishmaniasis
(CL) There are two different species that cause this; they are L. tropica
and L. major. They both have the same symptoms and life cycles but differ
in their geographic distribution. Both species can produce large numbers
of skin ulcers on the exposed parts of the body, such as the face, arms
and legs, causing serious disability and leaving the patient permanently
scarred. The infection site is usually localized to the site in which
the sand fly bite occurs. This form is caused by L. tropica
and L. major.
(World Health Organization)
Medical
Information
Leishmania is
a protozoan infection that is responsible for three primary diseases.
·
Systemic or Visceral leishmaniasis
Is the most sever of the three types of disease, in this form the parasite
becomes systemic (spread through out the entire body) by infecting macrophages
(immune cells) that in turn carry it to the spleen, liver and bone marrow.
The typical symptoms for this form of the disease are fever, night sweats,
fatigue, weakness, anorexia (appetite loss), weight loss, vomiting,
diarrhea, cough, skin lesions and hair loss. If visceral leishmaniasis
goes untreated it will usually result in death of the host do to liver
damage, fever, weight loss and often secondary infection do to the fact
that the macrophages are killed there by compromising the immune system.
Visceral leishmaniasis is extremely dangerous to people already infected
with HIV as the already compromised immune system is damaged even more
so by the loss of macrophages. (World Health Organization, Fact sheet
on Leishmania/HIV co-infection)
· Cutaneous
leishmaniasis
Is the most common form of leishmaniasis in which the epidermis is the
primary sight of infection. The symptoms associated with cutaneous leishmaniasis
are macule or papule erthematous (small raised skin lesions), skin ulcer
(extremely raw often-bleeding area of skin around sight of original
infection), satellite lesions (small lesions that form a few centimeters
from the original infection. Most of the time a person infected with
cutaneous leishmaniasis will survive the infection with out medical
intervention, although in developed nations it is usually treated nonetheless
to prevent disfigurement. In weak individuals cutaneous leishmaniasis
can progress to visceral leishmaniasis.
· Mucocutaneous
infection
Usually occurs when the original sight of infection is near mucous membrane,
although it can also result from visceral or cutaneous infections. The
symptoms include nasal stuffiness, runny nose, bleeding of nose, rectum
and vagina, ulcers and erosions of mouth, nose, tongue, gums, lips,
rectum, vagina. This form of leishmaniasis typically requires rapid
treatment in order to prevent extreme deformities to the infected area.
Mucocutaneous infections will often advance to visceral infections if
not treated.
(MEDLINEplus Medical Encyclopedia)
Testing
for Leishmania
For cutaneous mucocutaneous infections skin biopsy fallowed by culturing
of biopsy material is the most common way to check for Leishmania infections.
For visceral infections spleen or bone marrow biopsies are possible,
and the most accurate tests, but are also very expensive and require
invasive surgery. The more common test is to draw blood, and test the
blood with florescent antibodies to check for the presence of Leishmania.
Complementary tests that can be performed include CBC (shows decreased
cellularity of blood), hemoglobin (shows signs of anemia), serum protein
(decreased), serum albumin (decreased) and immunoglobulins (increased).
(MEDLINEplus Medical Encyclopedia)
Treatments
for Leishmania
The most commonly used cheapest and most effective chemotherapies for
Leishmania infections are antimony-containing compounds such as Meglumine
or Amphotericin B7. However many people have rather severe allergies
to these compounds, plus they have been shown to be dangerous to those
who are pregnant, breast feeding, or likely to become pregnant in the
next year. Another option in the case of allergy to the antimony compounds
is Sodium stibogluconate, however this drug is less effective and has
been shown to more often result in drug immune Leishmania. In the case
of cutaneous Leishmania infections Paromomycin that is an antimony topical
ointment is an option. In sever cases were drug immunity is present
it may be necessary to remove the spleen; this however is not always
effective, and often not possible in developing nations.
(The Medical Letter)
Prevention
of Leishmania
So far all attempts to create a preventative vaccine have been unsuccessful.
However there is some evidence that people who have had cutaneous infections
have heightened resistance to future visceral or cutaneous infections
so some researchers are looking into the possibility of infection with
an attenuated strain in the epidermis to cause a mild cutaneous infection.
At present the only effective preventative measure is to prevent sand
fly bites either by killing them with pesticides or by using insect
repellents.
(National Institute of Health)
Control
of Leishmaniasis
Since 1993, regions that are Leishmania-endemic have expanded significantly;
this is most likely due to development, like the massive rural-urban
migration in many developing nations. Also man-made projects with environmental
impact, like dams contribute to the spread of Leishmaniasis.
(World Health Organization)
Leishmaniasis currently threatens 350 million men, women and children
in 88 countries around the world. (CDC)
It is found in Africa, Asia, Europe, North America and South America.
 
Pictures
Courtesy of University of East London
In endemic areas such as Bangladesh and India sand fly control is often
combined with malaria control. Mass spraying with chemicals such as
DDT, Malathion, Fenitrothion, Propoxur and Diazinon is used to controle
sand fly populations. Self-protection is important; several methods
are available to avoid being bitten by sand flies including repellents
such as diethyltoluamide (DEET) applied to the exposed areas of the
body and clothing. Fine mesh screens can be applied to doors and windows
and bed nets should be used impregnated with insecticides such as permethrin
and deltamethrin. Mosquito nets are not effective since sand flies can
get through the holes.
(University of East London)
There
is no vaccines or drugs discovered yet to prevent the infection of Leishmania.
The best way to prevent infection is to prevent being bit by an infected
sand fly. Sand flies are controlled in many courtiers such as Bangladesh
and India by mass spraying of chemicals such as DDT, Malathion, Fenitrothion,
Propoxur and Diazinon.
Screening and treatment of domestic animals especially dogs is recommended
Authors:
Rasha Khatib, Stephen Jones
Creation/revision date: 03/04/2003 |
