Leishmania tropica
Amastigotes
The average roundish to oval amastigote measures 5 by 3 ?m in size. The amastigote consists of a nucleus and a kinetoplast. The large single nucleus is typically located off – center, sometimes present more toward the edge of the organism. The dotlike belpheroplast gives rise to and is attached to a small axoneme. The axoneme extends to the edge of the organism. The single parabasal body is located adjacent to the belpheroplast.
Promastigotes
The typical Promastigote measures 9 to 15 ?m in length. The large single nucleus is located in or near the center of the long and slender body. The kinetoplast is located in the anterior end of the organism. A single free flagellum extends anteriorly from the axoneme
Life cycle
Sandflies of the genera Phlebotomus are responsible for transmitting Leishmania tropica promastigotes into unsuspecting humans via blood meal, resulting in a skin bite. The promastigotes quickly invade the reticuloendothelial cells and transform into amastigotes, which actively reproduce, causing tissue destruction reproduction and invasion of additional cells then occurs . The skinand mucous membrane areas of the body are primarily affected. The amastigote serves as the infective stage for the sandfly. Upon ingestion, during a blood meal of an infected human, the amastigotes transform back into promastigotes in the fly midgut. These promastigotes multiply, and the resulting developed forms eventually migrate into the salivary gland of the fly, where they are ready to be transferred to a new human during a blood meal. Thus the cycle repeats itself.
Clincal symptoms
Cutaneous Leishmaniasis. Also known as Old World leishmaniasis, Oriental sore, and Baghdad or Delhi boil, cutaneous leishmaniasis is characterized by one or more ulcers containing pus that generally self – heal. Infected patients initially develop a small red papule , located at the bite site , that a typcally 2cm or more in diameter and may cause intense itching . the incubation time and the appearance of the papule vary with each subspecies . diffuse cutaneous leishmaniasis ( DCL ) occurs especially on the limbs and face when immune response fails to take place .
Laboratory diagnosis
Laboratory diagnosis of L. tropica consists of microscopic examination og Giemsa – stained slides of aspiration of fluid underneath the ulcer bed for the typical amastigotes. Culture of the ulcer tissue may also reveal the promastigote forms.