Black- fever

Leishmania Donovani 

Leishmania is a common common  parasite causes KALA AZAR or DUMDUM FEVER or BLACK FEVER in man. The secondary host is the blood sucking sandflies- Genus- Phlebotomus. Parasite generally infects the blood or liver cells and spleen.

• Habits and Habitat 

     In man L.donovani lives as an intracellular parasite in Leucocytes or cells of liver, spleen, bone-narrow, Lymphatic glands etc. Whereas in sand fly it undergoes multiplication and biological changes in the fire gut and salivary glands .

 Occurrence

   The parasite is common in Assam, Bangal, Bihar,U.P, Madras. It is also reported in Chain, Sudan, and in some parts of Africa and South America.

 Shape and Size

It is related like with pointed anterior end and slightly blunt posterior end. It is generally 2 to 4ú in diameter.

Structure

 Leishmania is diamorphic animal found in two forms-

Amastigote or Leishmania from:-

It occurs in reticulo endothelial cells of man . It is devoid of flagellum. Small, oval and colourless. Body is surrounded by athin elastic covering the pellicle .A big ecentric and active nucleus is situated in the centre and covered by nulcear membrane . Axoneme is present. Blepharoplasty and kinetoplast are connected with rhinoplasty.

Leptomonad or promastigote form:-

  Found in sand fly midgut . It is elongated, slender and spilndle shaped with large nucleus, blepharoplasty, kinetoplast and a long free flagellum. It is 15-20ù in width.

                 This form is uniflagellate. Each flagellum contain 9 periphiper and two central fibrils . Kinetoplast, blepharoplasty are as usual cytoplasm is colourless , homogenous and not differentiated in ectoplasm and endplasm. Nucleus is vesicular and distinct nucleolus. It is covered by double nuclear membrane having pores and 1ú in dimeter.

Life-cycle:

                As soon as the female sand fly bites a healthy person, it inoculated saliva in the body along with parasite of Leishmania . It become rounded or cells of blood, liver , or spleen . From there is derived its nourishment to through simole diffusion. After that nucleus enlarges and it undergoes repeated binary fission producing large number of parasites. By the pressure of large number of parasite ththe wall bursts. Again it attacks the fresh cells. By affecting large number of cells human beings suffers from a disease known as kala- AZAR. If this disease is not treated properly in time , then it becomes fatal.
                 When the sand fly sucks blood from a person suffering from Kala azar large number of parasites enters the body of fly . In the forget, it's it's amastugote firm turn into mastigote one and . After a week it migrated to salivary gland through hypopharynx. It sucks blood to a person and life cycle repeats.