Types of Leishmaniasis

Study Notes

Cutaneous leishmaniasis causes skin sores.
Visceral leishmaniasis (kala-azar) affects several internal organs, usually the spleen, liver, and bone marrow.
Mucosal leishmaniasis causes sores in the mucous membranes of the nose, mouth, or throat.

It is a chronic systemic disease that mainly affects children under five years of age.
It may be associated with malnutrition and other conditions of immunosuppression, such as HIV-AIDS.
If adequate treatment is not initiated in a timely manner, it can progress to death in 90% of cases.
The species commonly found in East Africa and the Indian subcontinent is L. donovani, while the species found in Europe, North Africa, and Latin America is L. infantum (also known as L. chagasi).

The natural habitat of L. donovani in humans is the reticuloendothelial system of the viscera.
The amastigote multiplies by simple binary fission until the host cells are destroyed, and then new macrophages are parasitized.
The amastigote stage appears as an ovoidal or rounded body, measuring about 2-3μm in length.

The organs of the reticuloendothelial system (liver, spleen, and bone marrow) are the most severely affected organs.
Reduced bone marrow activity, coupled with cellular distraction in the spleen, results in anemia, leukopenia, and thrombocytopenia.
This leads to secondary infections and a tendency to bleed.
The spleen and liver become markedly enlarged, and hypersplenism contributes to the development of anemia and lymphadenopathy.

The incubation period can range from 10 days to 24 months, with an average of 2-6 months.
Classic manifestations of VL include fever, splenomegaly, hepatomegaly, pallor, leukopenia, weight loss, and cachexia.
Other signs and symptoms include respiratory problems, gastrointestinal disturbances, malnutrition, and lower limb edema.

Parasitological tests are performed by detecting parasites in infected tissues, mainly in the bone marrow, through direct examination or isolation in culture (in vitro).
Molecular tests detect Leishmania DNA through the PCR method.
The immunological test currently available at the primary level is the rapid immunochromatographic test based on recombinant rK39 antigen.

The drug of choice is sodium stibogluconate, a pentavalent antimonial compound.
Alternative approaches include the addition of allopurinol and the use of pentamidine or amphotericin B.
Prevention involves prompt treatment of human infections and control of reservoir hosts, as well as protection from sand flies by screening and insect repellents (DEET).