LEISHMANIASIS
Introduction
In 1903, Leishman and Donovan separately described a protozoan parasite found
in the splenic tissue of patients in India. Their simultaneous discovery of
the protozoan now called Leishmania donovani first alerted the scientific
community to the life threatening disease of visceral leishmaniasis. Now a century
later, millions are still afflicted by Leishmania. It is a disease known for
its complexity and diversity. It is endemic in regions ranging from the rainforests
of South America to the deserts of Asia, and afflicts both rural and urban communities.
A host of about 21 different species of Leishmaniasis are classified under its
primary syndromes; cutaneous, mucocutaneos and visceral, which result from parasite
multiplication in macrophages in the skin, nasal-oral mucosa and internal organs,
respectively. These protozoan species are transmitted by over 30 species of
phlebotomine sand flies.
While most modes of transmission are vector borne, some are congenital and parenteral (ie, by blood transfusion, needle sharing, and laboratory accident). HIV and Leishmania co-infection has become a significant concern for developing nations with high numbers of HIV immuno-compromised individuals. Also increases in travel and international migration have brought this disease to the attention of developed nations. Available treatments for leishmaniasis are expensive or have serious associated toxicities and may lead to the development of drug-resistant parasites. Prevention and control regimens focusing on vector reservoir control had not changed in decades. However international attention has now shifted towards the development of effective and cost-efficient treatment. Exciting recent advances in diagnosis, treatment, prevention make now the most interesting time to research and learn about Leishmaniasis.
Basic Information on Leishmaniasis
Family: Trypanosomatidae
Genus: Leishmania
Synonyms: kala-azar meaning "black fever" in India, espundia (mucocutaneous form), uta in the Peruvian Andes
Clinical Presentations in Humans:
-Cutaneous Leishmaniasis: Lesions on exposed areas on the body that grow and spread with time. Diagnosis is made by visualizing the parasite. Samples taken from leading edge of lesion
-Mucocutaneous Leishmaniasis: Ulcers on the oral or nasal mucosa. If untreated, all of the nasal mucosa will be infected and the septum will be destroyed. this form of the disease usually spreads more widely than the cutaneous form. Diagnosis is made by visualizing the parasite. Samples taken from leading edge of lesion
- Visceral Leishmaniasis: Abdominal swelling without definite illness, anemia, dermal nodules or lesions resembling leprosy. Diagnosis is made by visualizing the parasite. Samples taken from a sternal marrow aspiration
Transmission: Inoculation by sandfly vector
Reservoir: Many diverse reservoir species: small mammals, dogs, varies with location
Vector: 30 species of Sandfly
Incubation Period: Two weeks to three years
Leshmania Species
Clinical Disease | Leishmania Species | Geographic Location | Vector (Sandfly Species) | Most Common Signs and Symptons | Incubation Period |
Cutaneos | L. tropica complex | Old World | Phlebotomus | Oriental sore | |
L. tropica | Armenia, Azerbaijan, Turkmenistan, Uzbekistan | Chronic lesions on face ulcerate after several months | 2 months-3 years | ||
L. aethiopica | Ethiopia, Kenya, Yemen | Chronic lesions on face ulcerate after several months | 2 months-3 years | ||
L. major | Middle East, Northern and Saharan Africa | Acute infection, 3-6 months: lower limbs | 2 weeks + | ||
L. mexicana complex |
New World
|
Lutzomyia | |||
L. mexicana | Belize, Yucatan Peninsula, Guatemala, Texas | Chiclero ulcer or Bay sore on ear or face | |||
L. pifanoi | Mato Grosso State in Brazil, Venezuela | Diffuse. Single lesion initially and then spreads over months and years. Does not ulcerate or heal | |||
L. amazonensis | Belém, Brazil | Diffuse | |||
L. garnhami | Venezuela | ||||
L. venezuelensis | Venezuela | ||||
L. brazieliensis complex | New World | Lutzomyia | |||
L. peruviana | Peruvian Andes | One or a few small self-healing lesions. Known locally as uta | |||
L. guyanensis | The Guyana, Brazil | Single skin ulcers, but lymphatic spread may result in widespread ulceration. Known locally as pian bois. | |||
L. panamensis | Panama, Costa Rica, Columbia | Single skin ulcers, but lymphatic spread may result in widespread ulceration | |||
L. lainsoni | Brzail, Peru | ||||
L. colombiensis | Colombia, Venezuela, Panama | ||||
L. infantum | Old World | ||||
L. chagasi | New World | ||||
Mucocutaneous | L. brazieliensis complex | New World | Lutzomyia Psychodopygus | ||
L.brazieliensis | Brazil | Ulcers in nasal or oral mucosa spread slowly without treatment. Known locally as espundia | weeks-years | ||
L. guyanensis | The Guyanas, Brazil | Same as L. brazieliensis or cutaneous | |||
L. panamensis | Panama, Costa Rica, Colombia | Same as L. brazieliensis or cutaneous | |||
L. mexicana | New World | ||||
L. tropica | Ethiopia, Sudan | Ulcerations of lip, mouth, or nose. Not as extensive as L. brazieliensis | |||
L. major | Ethiopia, Sudan | Ulcerations of lip, mouth, or nose. Not as extensive as L. brazieliensis | |||
Visceral | L. donovani complex | Known in India as kala-azar. hepatosplenomegaly | 2 weeks-18 months | ||
L. donovani | Asia, Africa | ||||
L. infantum | Old World | ||||
L. chagasi | New World | ||||
L. tropica | Old World | ||||
L. amazonensis | New world | ||||