leishmaniasis

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Leishmaniasis

 

Definition

Leishmaniasis refers to several different illnesses caused by infection with an organism called a protozoan.

Description

Protozoa are considered to be the most simple organisms in the animal kingdom. They are all single-celled. The types of protozoa that cause leishmaniasis are carried by the blood-sucking sandfly. The sandfly is referred to as the disease vector, simply meaning that the infectious agent (the protozoan) is carried by the sandfly and passed on to other animals or humans in whom the protozoan will set up residence and cause disease. The animal or human in which the protozoan then resides is referred to as the host.
Once the protozoan is within the human host, the human's immune system is activated to try to combat the invader. Specialized immune cells called macrophages work to swallow up the protozoa. Usually, this technique kills a foreign invader, but these protozoa can survive and flourish within macrophages. The protozoa multiply within the macrophages, ultimately causing the macrophage to burst open. The protozoa are released, and take up residence within other neighboring cells.
At this point, the course of the disease caused by the protozoa is dependent on the specific type of protozoa, and on the type of reaction the protozoa elicits from the immune system. There are several types of protozoa that cause leishmaniasis, and they cause different patterns of disease progression.
At any one time, about 20 million people throughout the world are infected with leishmaniasis. Between one million and one and one-half million cases of cutaenous leishmaniasis are reported yearly worldwide. While leishmaniasis exists as a disease in 88 countries on five continents, some countries are hit harder than others. These include Bangladesh, India, Nepal, Sudan, Afghanistan, Brazil, Iran, Peru, Saudi Arabia, and Syria. Other areas that harbor the causative protozoa include China, many countries throughout Africa, Mexico, Central and South America, Turkey, and Greece. Although less frequent, cases have occurred in the United States, in Texas.
As Americans travel to these countries, they will come in contact the protozoa that cause forms of leishmaniasis. Also, physicians were advised in 2004 to suspect cutaneous leishmaniasis in military personnel who were deployed to areas where the infection is present. From August 2002 to February 2004, staff from the U.S. Department of Defense identified 522 confirmed cases of the disease in American military personnel.
In some areas of southern Europe, leishmaniasis is becoming an important disease that infects people with weakened immune systems. In particular, individuals with acquired immunodeficiency syndrome (AIDS) are at great risk of this infection.

Causes and symptoms

There are a number of types of protozoa that can cause leishmaniasis. Each type exists in specific locations, and there are different patterns to the kind of disease each causes. The overall species name is Leishmania (commonly abbreviated L.). The specific types include: L. Donovani, L. Infantum, L. Chagasi, L. Mexicana, L. Amazonensis, L. Tropica, L. Major, L. Aethiopica, L. Brasiliensis, L. Guyaensis, L. Panamensis, L. Peruviana. Some of the names are reflective of the locale in which the specific protozoa is most commonly found, or in which it was first discovered.

Localized cutaneous leishmaniasis

This type of disease occurs most commonly in China, India, Asia Minor, Africa, the Mediterranean Basin, and Central America. It has occurred in an area ranging from northern Argentina all the way up to southern Texas. It is called different names in different locations, including chiclero ulcer, bush yaws, uta, oriental sore, Aleppo boil, and Baghdad sore.
This is perhaps the least drastic type of disease caused by any of the Leishmania. Several weeks or months after being bitten by an infected sandfly, the host may notice an itchy bump (lesion) on an arm, leg, or face. Lymph nodes in the area of this bump may be swollen. Within several months, the bump develops a crater (ulceration) in the center, with a raised, reddened ridge around it. There may be several of these lesions near each other, and they may spread into each other to form one large lesion. Although localized cutaneous leishmaniasis usually heals on its own, it may take as long as one year. A depressed, light-colored scar usually remains behind. Some lesions never heal, and may invade and destroy the tissue below. For example, lesions on the ears may slowly, but surely, invade and destroy the cartilage that supports the outer ear.

Diffuse cutaneous leishmaniasis

This type of disease occurs most often in Ethiopia, Brazil, Dominican Republic, and Venezuela.
The lesions of diffuse cutaneous leishmaniasis are very similar to those of localized cutaneous leishmaniasis, except they are spread all over the body. The body's immune system apparently fails to battle the protozoa, which are free to spread throughout. The characteristic lesions resemble those of the dread biblical disease, leprosy.

Mucocutaneous leishmaniasis

This form of leishmaniasis occurs primarily in the tropics of South America. The disease begins with the same sores noted in localized cutaneous leishmaniasis. Sometimes these primary lesions heal, other times they spread and become larger. Some years after the first lesion is noted (and sometimes several years after that lesion has totally healed), new lesions appear in the mouth and nose, and occasionally in the area between the genitalia and the anus (the perineum). These new lesions are particularly destructive and painful. They erode underlying tissue and cartilage, frequently eating through the septum (the cartilage that separates the two nostrils). If the lesions spread to the roof of the mouth and the larynx (the part of the wind pipe which contains the vocal cords), they may prevent speech. Other symptoms include fever, weight loss, and anemia (low red blood cell count). There is always a large danger of bacteria infecting the already open sores.

Visceral leishmaniasis

This type of leishmaniasis occurs in India, China, the southern region of Russia, and throughout Africa, the Mediterranean, and South and Central America. It/is frequently called Kala-Azar or Dumdum fever.
In this disease, the protozoa use the bloodstream to travel to the liver, spleen, lymph nodes, and bone marrow. Fever may last for as long as eight weeks, disappear, and then reappear again. The lymph nodes, spleen, and liver are often quite enlarged. Weakness, fatigue, loss of appetite, diarrhea, and weight loss are common. Kala-azar translates to mean "black fever." The name kala-azar comes from a characteristic of this form of leishmaniasis. Individuals with light-colored skin take on a darker, grayish skin tone, particularly of their face and hands. A variety of lesions appear on the skin.

Diagnosis

Diagnosis for each of these types of leishmaniasis involves taking a scraping from a lesion, preparing it in a laboratory, and examining it under a microscope to demonstrate the causative protozoan. Other methods that have been used include culturing a sample piece of tissue in a laboratory to allow the protozoa to multiply for easier microscopic identification; injecting a mouse or hamster with a solution made of scrapings from a patient's lesion to see if the animal develops a leishmaniasis-like disease; and demonstrating the presence in macrophages of the characteristic-appearing protozoan, called Leishman-Donovan bodies.
In some forms of leishmaniasis, a skin test (similar to that given for TB) may be used. In this test, a solution containing a small bit of the protozoan antigen (cell marker that causes the human immune system to react) is injected or scratched into a patient's skin. In a positive reaction, cells from the immune system will race to this spot, causing a characteristic skin lesion. Not all forms of leishmaniasis cause a positive skin test, however.

Treatment

The treatment of choice for all forms of leishmaniasis is a type of drug containing the element antimony. These include sodium sitogluconate, and meglumin antimonate. When these types of drugs do not work, other medications with anti-protozoal activity are utilized, including amphotericin B, pentamidine, flagyl, and allopurinol. In 2004, it was reported that the world's first non-profit drug company was seeking approval in India for a drug to cure visceral leishmaniasis. An estimated 200,000 people die annually from the disease in that country. The company, called OneWorld Health, hoped to offer the drug called paromomycin for a day for a three-week treatment course.

Prognosis

The prognosis for leishmaniasis is quite variable, and depends on the specific strain of infecting protozoan, as well as the individual patient's immune system response to infection. Localized cutaneous leishmaniasis may require no treatment. Although it may take many months, these lesions usually heal themselves completely. Only rarely do these lesions fail to heal and become more destructive.
Disseminated cutaneous leishmaniasis may smolder on for years without treatment, ultimately causing death when the large, open lesions become infected with bacteria.
Mucocutaneous leishmaniasis is often relatively resistant to treatment. Untreated visceral leishmaniasis has a 90% death rate, but only a 10% death rate with treatment.

Prevention

Prevention involves protecting against sandfly bites. Insect repellents used around homes, on clothing, on skin, and on bednets (to protect people while sleeping) are effective measures.
Reducing the population of sandflies is also an important preventive measure. In areas where leishmaniasis is very common, recommendations include clearing the land of trees and brush for at least 984 ft (300 m) around all villages, and regularly spraying the area with insecticides. Because rodents often carry the protozoan that causes leishmaniasis, careful rodent control should be practiced. Dogs, which also carry the protozoan, can be given a simple blood test.

Resources

Periodicals

MacReady, Norma. "Leishmaniasis Hits Military Hot Spots." Internal Medicine News June 15, 2004: 58.
"Seeking First-time Approval." Chemist & Druggist May 8, 2004: 12.
"Treatment of Cutaneous Leishmaniasis Among Travelers Reviewed." Vaccine Weekly April 28, 2004: 58.

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

Key terms

Host — The organism (such as a monkey or human) in which another organism (such as a virus or bacteria) is living.
Larynx — The part of the airway lying between the pharynx and the trachea.
Leishman-Donovan body — A body of a (trypanosomatid) protozoa at a particular and characteristic stage in its life cycle; the infectious (trypanosomatid) protozoa can cause leishmaniasis, and is relatively easy to identify at that stage.
Lesion — A disruption of the normal structure and function of a tissue by some disease process.
Macrophage — A cell of the immune system that engulfs and digests foreign invaders such as bacteria and viruses in an attempt to stop them from causing disease within the body.
Protozoa — A group of organisms which are the smallest members of the animal kingdom, consisting of a single cell.
Ulceration — An area of pitting and irritation.
Vector — A carrier organism (such as a fly or mosquito) that to delivers a virus (or other agent of infection) to a host.

leishmaniasis

 [lēsh″mah-ni´ah-sis]
any disease due to infection with Leishmania.
American leishmaniasis forms of cutaneous leishmaniasis and visceral leishmaniasis found in the Americas.
cutaneous leishmaniasis an endemic disease transmitted by the sandfly and characterized by the development of cutaneous papules that evolve into nodules, break down to form ulcers, and heal with scarring. It has been divided into Old World and New World forms, and the Old World form is subdivided into urban and rural types. The Old World form is caused by organisms of the Leishmania tropica complex; the New World form is caused by organisms of the L. mexicana and L. viannia complexes. It is endemic in the tropics and subtropics, and has been called by various names such as Aleppo boil, Delhi sore, Baghdad sore, and Oriental sore. Treatment consists of injections of pentavalent antimonial compounds. Antibiotics are used to combat secondary infection. Simple lesions may be cleaned, curetted, and left to heal.
cutaneous leishmaniasis, diffuse a rare chronic form of cutaneous leishmaniasis caused by Leishmania aethiopica in Ethiopia and Kenya, L. pifanoi in Venezuela, and species of the L. viannia and L. mexicana subclass in South and Central America, respectively, in which the lesions resemble those of nodular leprosy or of keloid. Pentavalent antimonial compounds are useful in some forms, while others are antimony-resistant. The prognosis for a complete cure is not good; relapses are common.
mucocutaneous leishmaniasis a disease endemic in South and Central America caused by Leishmania viannia, marked by ulceration of the mucous membranes of the nose, mouth, and pharynx; widespread destruction of soft tissues in nasal and oral regions may occur. Called also espundia. Treatment consists of injections of pentavalent antimonial compounds.
leishmaniasis reci´divans a prolonged, relapsing form of cutaneous leishmaniasis resembling tuberculosis of the skin; it may last for many years.
visceral leishmaniasis a chronic, highly fatal if untreated, infectious disease endemic in the tropics and subtropics, caused by the protozoon Leishmania donovani. Sandflies of the genus Phlebotomus are the vectors. Called also kala-azar.
Symptoms. Symptoms are usually vague, resembling those of incipient pulmonary tuberculosis; the disease is often confused with malaria. There may be fever, chills, malaise, cough, anorexia, anemia, and wasting. The Leishmania organisms multiply in the cells of the reticuloendothelial system, eventually causing hyperplasia of the cells, especially those of the liver and spleen. Diagnosis is confirmed by demonstration of the parasite.
Treatment. Two groups of compounds are recommended: pentavalent organic antimonials, such as sodium antimony gluconate, and aromatic diamidines, such as pentamidine, if the antimonials are ineffective. Rest is prescribed for patients debilitated by anemia. A decrease in white cell count (leukopenia) often accompanies the disease, and therefore the patient's resistance to secondary infections is lowered. In some cases transfusion may be necessary to bring blood values back to normal. The patient is given a well balanced diet and liberal amounts of fluids. Special mouth care and attention to the skin are necessary to avoid complications.

leish·man·i·a·sis

(lēsh'măn-ī'ă-sis),
Infection with a species of Leishmania resulting in a clinically ill-defined group of diseases traditionally divided into four major types: visceral leishmaniasis (kala azar); Old World cutaneous leishmaniasis; New World cutaneous leishmaniasis; and mucocutaneous leishmaniasis. Each is clinically and geographically distinct and each has been newly subdivided into clinical and epidemiologic categories. Transmission is by various sandfly species of the genus Phlebotomus or Lutzomyia. See: tropic diseases.
Synonym(s): leishmaniosis

leishmaniasis

/leish·ma·ni·a·sis/ (lēsh″mah-ni´ah-sis) infection with Leishmania.
American leishmaniasis  any of the types of cutaneous or visceral leishmaniasis occurring in South America, Central America, or Mexico.
cutaneous leishmaniasis  an endemic granulomatous disease, divided into two forms: an Old World form caused by Leishmania major, L. tropica or L. aethiopica and a New World form caused by L. mexicana or L. viannia.
mucocutaneous leishmaniasis  chronic, progressive, metastatic spread of the lesions of New World leishmaniasis caused by Leishmania viannia braziliensis to the nasal, pharyngeal, and buccal mucosa long after the appearance of the initial cutaneous lesion, causing widespread destruction of tissue with marked deformity.
post–kala-azar dermal leishmaniasis  a condition associated with visceral leishmaniasis, characterized by hypopigmented or erythematous macules on the face and sometimes also the trunk and limbs, the facial lesions progressing to papules and nodules resembling those of lepromatous leprosy.
leishmaniasis reci´divans  a prolonged, relapsing form of cutaneous leishmaniasis resembling tuberculosis of the skin.
visceral leishmaniasis  a chronic, highly fatal if untreated, infectious disease caused by Leishmania donovani, characterized by hepatosplenomegaly, fever, chills, vomiting, anemia, leukopenia, hypergammaglobulinemia, and an earth-gray color of the skin.

leishmaniasis

(lēsh′mə-nī′ə-sĭs)
n.
1. An infection caused by any of the flagellate protozoans of the genus Leishmania, transmitted to humans and animals by bloodsucking sandflies.
2. A disease, such as kala-azar or either of two clinically distinct ulcerative skin diseases, caused by flagellate protozoans of the genus Leishmania.

leishmaniasis

[lēsh′mənī′əsis]
Etymology: William B. Leishman
infection with any species of protozoan of the genus Leishmania. The diseases caused by these organisms may be cutaneous, mucocutaneous, or visceral. The infection is transmitted to humans by several species of nocturnal Phlebotomus sandflies. Other species of the blood-sucking insects infect other animals. Diagnosis is made by microscopic identification of the intracellular nonflagellated protozoan on a Giemsa-stained smear taken from a cutaneous lesion or visceral biopsy. A typical infection may begin with a cutaneous sore and progress to ulceration of the mouth, palate, and nose. Some cases are accompanied by a febrile illness. There are three major types of leishmaniasis: American leishmaniasis, the form found in Central America and South America, kala-azar, and cutaneous. Visceral leishmaniasis occurs mainly in the tropical areas of Asia; cutaneous leishmaniasis is encountered most frequently in the Middle East. See also Leishmania. leishmanial, adj.
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Visceral leishmaniasis

leish·man·i·a·sis

(lēsh'mă-nī'ă-sis)
Infection with a species of Leishmania resulting in a group of diseases traditionally divided into four major types: 1) visceral leishmaniasis (kala azar); 2) Old World cutaneous leishmaniasis; 3) New World cutaneous leishmaniasis; and 4) mucocutaneous leishmaniasis.
See also: tropical diseases

leishmaniasis

(lesh?ma-ni'a-sis) [ Leishmania + -iasis]
Any of a group of related chronic parasitic diseases of the skin, viscera, or mucous membranes, caused by species of the genus Leishmania. Leishmaniasis has occurred in epidemics but occurs mostly as an endemic disease in Asia, Africa, Latin America, and the Middle East; U.S. military personnel overseas may be infected. One type of leishmaniasis, kala azar, causes visceral infection and involves the mononuclear phagocytic system, causing inflammation and fibrosis of the spleen and liver. It can be fatal if untreated. Mucosal leishmaniasis infection produces mutilating lesions that destroy the mucosa, esp. in the larynx, anus, and vulva. In the two cutaneous forms of leishmaniasis, multiple skin ulcers form on exposed areas of the face, hands, arms, and legs. These are not painful or contagious but, if left untreated, can leave permanent, disfiguring scars. Leishmania organisms infect and reproduce inside macrophages and are controlled by T-cell–mediated response. The strength of the patient's immune system determines the severity of the disease. See: kala azar

Patient care

There is no vaccine against Leishmania. To prevent infection during exposure to sandfly vectors, topical repellants containing 30% to 35% N, N-diethyl-3-methylbenzamide (DEET) should be applied to the skin; and permethrin should be used to impregnate clothing, uniforms, bed netting, and screened enclosures. These measures also protect against infections caused by other biting insects, e.g., malaria.

Treatment

Drugs used to treat leishmaniasis include amphotericin B, miltefosine, paromomycin, and sodium stibogluconate.

American leishmaniasis

Mucocutaneous leishmaniasis.

cutaneous leishmaniasis

An ulcerating, chronic, nodular skin lesion prevalent in Asia and the tropics and due to infection with Leishmania tropica. Synonym: Aleppo boil; Baghdad boil; Delhi boil; Oriental sore; tropical sore
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MUCOCUTANEOUS LEISHMANIASIS

mucocutaneous leishmaniasis

A form of cutaneous leishmaniasis, involving principally the nasopharynx and mucocutaneous membranes, found in parts of Central and South America. The causative organism is Leishmania braziliensis usually transmitted by sandflies of the genus Lutzomyia.
Synonym: American leishmaniasisillustration

tegumentary leishmaniasis

Leishmaniasis that involves the skin or mucous membranes.

visceral leishmaniasis

Kala azar.

Leishmaniasis

A group of infections, caused by single-celled microscopic parasites of the genus LEISHMANIA, and spread by sandflies. It can affect either the skin (cutaneous Leishmaniasis) or the internal organs (visceral Leishmaniasis or KALA AZAR). A seriously disfiguring form, ESPUNDIA, occurs in various parts of south America. Leishmaniasis is becoming increasingly important because of the volume of holiday traffic to areas in which it is endemic, especially the Mediterranean. See also DELHI BOIL, ORIENTAL SORE.

leishmaniasis

a human disease caused by infection with the protozoan flagellate Leishmania. There are several forms of leishmaniasis. A major type found in tropical and subtropical areas is called cutaneous leishmaniasis, in which severe pimpling and ulceration can cover face, arms and legs. Another species of Leishmania causes a lethal ‘visceral’ form of the disease in Africa and Asia, in which infection of the spleen, liver and other organs occurs producing symptoms of'kala-azar’ and ‘dum-dum fever’.

Leishman,

Sir William Boog, Scottish surgeon, 1865-1926.
Leishmania - a genus of digenetic, asexual, protozoan flagellates.
Leishman chrome cells - basophilic granular leukocytes (basophils) observed in the circulating blood of some persons with blackwater fever.
Leishman stain - a polychromed eosin-methylene blue stain used in the examination of blood films.
Leishman-Donovan body - the intracytoplasmic, nonflagellated leishmanial form of certain intracellular parasites. Synonym(s): amastigote; L-D body
leishmaniasis - tropical disease that is spread by sandflies.

leishmaniasis

infection with Leishmania species (endemic in Asia, the Middle East, Africa, southern Europe and Latin America) transmitted by bite from female sandfly; causes initial pruritic papule (e.g. of plantar skin), thence nodule formation, then inflammation and ulceration 6-8 weeks later; healed lesions show pigmented scarring; patients should be referred for specialist advice

leish·man·i·a·sis

, leishmaniosis (lēsh'mă-nī'ă-sis, -nē-ōsis)
Infection with a species of Leishmania resulting in a clinically ill-defined group of diseases traditionally divided into four major types: visceral leishmaniasis (kala azar); Old World cutaneous leishmaniasis; New World cutaneous leishmaniasis; and mucocutaneous leishmaniasis.

leishmaniasis

(lēsh´mənī´əsis),
n an infection with a species of protozoan of the genus
Leishmania.

leishmaniasis, leishmaniosis

infection by Leishmania spp.; occurs in humans, domestic Canidae and rodents, and is an important zoonosis throughout the world, except Australia. Three forms occur: (1) visceral (kala-azar, black fever, dumdum fever), caused by L. donovani; (2) cutaneous (Oriental sore, Bagdad boil, Aleppo button), caused by L. tropica; and (3) mucocutaneous, caused by L. brasiliensis. Visceral leishmaniasis in the dog is a chronic, debilitating disease with weight loss, enlargement of the liver and spleen, and polyarthritis. Chronic ulcerations of the skin occur in the cutaneous form.