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