Leishmanisis | causes| sign & symptoms| Treatment|

leishmeniasis vector bone disease
Leishmaniasis is a chronic inflammatory disease of the skin, mucous membranes, or viscera caused by obligate intracellular, kinetoplast containing (kinetoplastid) protozoan parasites transmitted through the bite of infected.
Leishmaniasis is endemic throughout the Middle East, South Asia, Africa, and Latin America.
It may also be epidemic, as is tragically the case in Sudan, India, Bangladesh, and Brazil, where tens of thousands of people have died of visceral leishmaniasis.
*Pathogenesis*. The life cycle of Leishmania involves two forms: the promastigote, which develops and lives extracellularly in the sandfly vector, and the amastigote, which multiplies intracellularly in host macrophages.
Mammals, including rodents, dogs, and foxes, are reservoirs of Leishmania
Cutaneous disease
• Old World—Leishmania major and Leishmania tropica
• New World—Leishmania mexicana and Leishmania
braziliensis
• Mucocutaneous disease (also called espundia)
• New World—L. braziliensis
• Visceral disease involving the liver, spleen, and bone
marrow
• Old World—Leishmania donovani and Leishmania
infantum
• New World—Leishmania chagasi

Tropism of Leishmania species seems to be linked in part to the optimal temperature for their growth.
Parasites that cause visceral disease grow best at 37°C, whereas parasites
that cause mucocutaneous disease grow better at lower temperatures.

In visceral leishmaniasis, parasites invade macrophages throughout the mononuclear phagocyte system and cause severe systemic disease marked by hepatosplenomegaly, lymphadenopathy, pancytopenia, fever, and weight loss.
Cutaneous leishmaniasis is a relatively mild, localized disease consisting of ulcers on exposed skin.
The lesion begins as a papule surrounded by induration, changes into a shallow and slowly expanding ulcer, often with heaped-up borders,
and usually heals by involution within 6 to 18 months without
treatment.
On microscopic examination, the lesion shows granulomatous inflammation, usually with many giant cells and few parasites.

Mucocutaneous leishmaniasis is found only in the NewWorld.
Moist, ulcerating, or nonulcerating lesions develop in the nasopharyngeal areas and, with progression, may be highly destructive and disfiguring. Microscopic examination reveals a mixed inflammatory infiltrate composed of parasite-containing macrophages with lymphocytes and plasma cells.

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