Leishmania donovani is also known as Kala Azar. It is characerized by a enlarged spleen because the immune system trys to limit the progression of the disease.
1. Promastigote forms in the Phlebotomus fly
2. Fly bites a human and injects parasite into the skin
3. The parasite invades the recticuloendothelial cells
4. The amastigote reporduces asexually in the human cells and invades other lymphoid tissue (diagnostic stage)
5. When another Phlebotomus fly bits the human it injests the amastigote parasite
6. The amastigote transforms into the promastigote and reproduces int he midgut
7. The parasite then migrates to the probuscis where it is now ready to infect another human
This parasite attacks the internal organs of people who contract it. The spleen begins to grow because the immune system tries to limit the disease.