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Leishmaniasis

Title                    

Ñ    Leishmaniasis      

Definition

Ñ    A group of diseases caused by protozoa of the genus Leishmania

Aetiology

Ñ    Various species of the protozoan genus Leishmania

Pathogenesis

Vectors

Ñ    Sandflies:

·          Phlebotomous:

Old World

·          Lutzomyia:

New World

Reservoir of Infection

Ñ    Humans

Ñ    Animals:

Canines, rodents, sloths, anteaters

Rarely

Ñ    Spread by blood transfusion, congenital, sexual contact

Life cycle

Ñ    In the vertebrate host the protozoa are found as amastigotes:

Leishman-Donovan bodies

Ñ    They multiply within macrophages and cells of the reticuloendothelial system

Ñ    Released into the circulation when cells rupture

Ñ    Taken up into the gut of feeding sandfly

Ñ    Develop into flagellated promastigotes

Ñ    Migrate to salivary glands

Ñ    Inoculated into new host

 

 

Visceral Leishmaniasis

Title

Ñ    Visceral Leishmaniasis (Kala-Azar)

Aetiology

Parasites of Leishmania donovani complex:

Ñ    Leishmania donovani

Ñ    Leishmania infantum

Ñ    Leishmania chagasi

Vector

Ñ    Sandfly:      

Genus Phlebotomous

Pathogenesis

Ñ    Parasites inoculated by sandfly bite

Ñ    Migrate to reticuloendothelial system and multiply

Clinical Features

History

Incubation Period

Ñ    2 weeks to 1 year:

Usually 1-2 months

E&M

Ñ    Fever

Ñ    Emaciation

Examination

E&M

Ñ    Emaciation

IS                           

Ñ    Primary lesion at the site of inoculation is small and usually not apparent

Ñ    Skin rough

Ñ    Pigmentation

HS

Ñ    Hepatosplenomegaly

Ñ    Lymphadenopathy:

African kala-azar

Ñ    Pancytopaenia

Ñ    Polyclonal hypergammaglobulinaemia

Complications

IS

Ñ    1-2 years after apparent cure nodular cutaneous lesions full of parasites may develop

Ñ    This is known as Post Kala-Azar Dermal Leishmaniasis (PKDL)

Investigations

Fluids

Smears

Ñ    Parasites may be demonstrated in Giemsa stained smears of aspirates from:

Bone marrow, lymph nodes, spleen, liver

Culture

Ñ    Organisms may be cultured from aspirates of the:

Bone marrow, lymph nodes, spleen, liver

Blood

Haematology

Ñ    Pancytopaenia

Biochemistry

Ñ    Hypoalbuminaemia

Ñ    Hypergammaglobulinaemia

Immunology

Ñ    Specific serology:

Positive in 95% of patients

Tissue diagnosis

Ñ    Leishmanin (Montenegro) Skin Test (intradermal injection of Leishmania antigen):

Negative, indicating poor cell mediated immune response

Management

Cure

Drugs

Ñ    Pentavalent antimony salts:

Sodium stibogluconate

Ñ    Amphotericin B

Ñ    Pentamidine

Ñ    Miltefosine

Prevention

Drugs

Ñ    Mass treatment of patients

Biological agents

Ñ    Vector reduction

Equipment

Ñ    Insect screens

Ñ    Insect repellents

Prognosis

Ñ    Without treatment emaciation and death occur in 80-90% of untreated patients

 

 

Cutaneous Leishmaniasis                       

Title               

Ñ    Cutaneous Leishmaniasis                     

Aetiology

Ñ    Leishmania major, L. tropica, L. aethiopica

Southern Europe, Asia and Africa

Ñ    Leishmania mexicana complex

Mexico, Central and South America

Ñ    Leishmania braziliensis complex

Central and South America

Pathogenesis

Ñ    Sandfly bite

Ñ    Amastigotes multiply in dermal macrophages

Response depends on

Ñ    Species

Ñ    Size of inoculum

Ñ    Host response

Clinical Features

History

Incubation Period

Ñ    1 week to 3 months

IS

Ñ    Painless ulcer:

This generally heals over several months leaving a depressed scar

In the New World skin lesions may be followed by metastatic mucocutaneous lesions

Examination

IS

Ñ    Single lesion

Ñ    Multiple lesions:

Caused by:

·          Multiple bites

·          Accidental autoinoculation

·          Metastatic spread

Ñ    The lesion begins as a papule that enlarges and ulcerates centrally

Ñ    Border raised, hyperpigmented

Complications

IS

Ñ    Diffuse cutaneous leishmaniasis (rare):

Diffuse infiltration of the skin

Investigations

Fluids

Smear

Ñ    Giemsa stain of split skin smear

Tissue Diagnosis

Ñ    Leishmanin Test:

Positive

Does not help to distinguish between active and resolved infection

Ñ    Biopsy:

Histology

PCR

Management

Ñ    Cutaneous leishmaniasis may be divided into that of the Old World (Africa, Mediterranean, Afghanistan) and cutaneous leishmaniasis of the New World (Central and South America)

Ñ    Cutaneous leishmaniasis of the Old World heals in 4 to 18 months leaving a scar

·          No serious sequelae occur

·          It may be left alone

·          It could be frozen with liquid nitrogen

·          A pentavalent antimonial such as sodium stibogluconate may be administered intralesionally

Ñ    Cutaneous leishmaniasis of the New World runs a more protracted course and should be treated

 

Cure

Drugs

Ñ    Topical antiparasitic agents:

Intralesional antimonials

Ñ    Systemic treatment:

Sodium stibogluconate

Pentamidine

Amphotericin B

Surgery

Ñ    Curettage

Ñ    Cryotherapy

 

 

Mucocutaneous Leishmaniasis                       

Title               

Ñ    Mucocutaneous Leishmaniasis                     

Aetiology

Ñ    Leishmania braziliensis

Clinical Features

History

Incubation Period

Ñ    2-3months

IS

Ñ    Cutaneous sores

RS

Ñ    Ulcerating lesions of the mucosa or cartilage of the nose (espundia) occur months or years after the cutaneous lesions

GIT

Ñ    Ulcerating lesions of the lips may occur months or years after the cutaneous lesions

Complications

RS

Ñ    Gross mutilation of the nose

GIT

Ñ    Gross mutilation of the palate

Investigations

Ñ    As for cutaneous leishmaniasis but parasites difficult to isolate

Management

Cure

Drugs

Ñ    Amphotericin B:

Treatment of choice

Ñ    Systemic antimony compounds

 

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