Biological Diversity 2003   

title of photo

Kingdom: Protisata
Phylum: Sarcomastigophora
Class: Zoomastrgophora
Order: Kimetplastida
Family: Trypanosomatidae
Genus: Leishmania
Species: Donovani , Tropica, Mexicana,Braziliensis

 

 

title of photo
(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)

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



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This website is part of a Biology 226 class project on the conservation of global biodiversity.


Earlham · Biology Department · Biology 226: Biological Diversity

Copyright ©-2001 Earlham College. Revised 16 November 2001. Send corrections or comments to Steve Jones or Raha Khatib
Last updated 04/04/03