Diagnosis of kala-azar

Direct method – This is conclusive test for the demonstration of L.D bodies . The finding of the parasite may be obtained by following ways –

 A.. By the examination of smears from –

(a)    Peruipheral Blood –

    

i)                    By making a thick blood film

ii)                  B producing a straight leucocytic edge .

iii)                By centrifuging a citrated blood .

(b)    Spleen or liver puncture

(c)    Sternal puncture .

B.. Culture – The organism may be cultured in citrated blood in a moist tube of N.N.N medium ( novy Mac Neal Nicolle medium ).

    

Indirect method –

A.. blood coungt

  

a)      Haemoglobin percentage – about 40%

b)      Total count of R.B.C – Decreased .

c)      Total count of W.B.C – Leucopenia ( about 3000/cmm)

d)     Total count of platelet – Normal or below .

e)      Differential count –

a)      Neutropenia

b)      Absence of Eosinophil

c)      Lymphocytosis

d)     Monocytosis .

B..  Serological test

1.      Test based on increase of globulin of blood –

(a ) Aldehyde test -  This test depend on an  increase of serum gamma globulin . The test will not be positive in case of less than three months duration of the disease and in this period , the spleen will enlarged .

(b) Chopra’s antimony test – The test depend upon an increase of serum gamma globulin .

2.. Test based on the presence of antibody in the serum

( a ) Compliment fixation test with W.K.K antigen – The test is a distinct advantage for early diagnosis of kala-azar .

     (b) agglutination test – Usually this test is not done .

Pathological changes of different organs due to Kala-azar

1.. Spleen

a)      Splenomegaly

b)      Thickened splenic capsule

c)      Consistency – soft

d)     Cut surface shows congestion and ;dull red or chocolate colour .

e)      Microscopically

i)                    Vascular spaces are filled up with blood .

ii)                  Increased reticular cells and L.D body are markedly present .

iii)                Malpighian corpuscles disappear .

 2.. Liver

i)                    Hepatomegaly

ii)                  Cut surface shows nutmeg appearance .

iii)                Microscopically –

a)      Kupffer’s cells are packed with LD bodies and the size and number of the cell are highly increased

b)      Sinusoides are filled up with blood .

c)      There is no changes of fibrous tissue .

  3.. Bone marrow

i)                    There will be extensive hyperplasia of reticuloendothelial tissue

ii)                  Due to the disturbance of haemopoietic activities of bone marrow , there will be leucopenia particularly neutropenia .

iii)                Microscopically –

a)      L.D bodies will be present

b)      Parasitised macrophage cell present .

4.. Lymph node – L.D body may be present in the lymph node .

5.. Intestine -  intestinal ulcers may be present  in case of kala-azar but this is due to secondary infection .

6.. Anaemia in kala-azar – There will be normocytic and orthochromic anaemia . But there may be macrocytic hyperchromic anaemia or aplitic anaemia in kala-azar .

7.. Jaundice in kala-azar – Jaundice may be produced due to damage of liver cell .

Morphology of LEISHMANIA DONOVANI

1. Leshmanial form or Aflagellar stage or Amastigote stage –

i)                    Shape – Oval or round .

ii)                  Size – 2 to 4 μ along the long axis .

iii)                Nucleus – Oval or roun d .

iv)                Kinetoplast –

(a)    Rod like parabasal body

(b)    A  dot like blepharoplast .

v)                  Rhizoplast or Axoneme – A delicate filament  may be seen which extends from kin etoplast to margin of the body .

vi)                Cytoplasm  - Blue .

vii)              Vacuole – a clear unstained space .

2. Leptomonad form or Flagellar stage or promastigote stage –

i)                    Shape – spindle shaped

ii)                  Size – 10 to 12 μ in length and 1 to 2 μ in breadth .

iii)                Nucleus – Situated centrally .

iv)                Kinetoplast – Transversely situated near anterior end .

v)                  Eosinophilic vacuole – A light staining area .

vi)                Flagellum .

Life cycle of LEISHMANIA DONOVANI

Leishmania Donovani has two stages in its life cycle –

    A .. Leishmanial form in the Mammallam host –

i)                    Man , dog or a wild rodent may be infected .

ii)                  During the blood meal , the infected sandfly introduces the leptomonad form of L.D body . The leptomonad forms are taken up by macrophages and change into leishmanial forms

iii)                In the human beings , the leishmanial forms will reside in the cells of reticulo endothelial system  . these will multiply by binary fission .

iv)                When the cells become packed with the parasite , the macrophages will enlarged and ultimately rupture . Then the parasite enter into circulation and are engulfed by new macrophages and cycle is repeated . Ultimately the entire R.E system becomes infected . This leishmanial form may be engulfed by neutrophils and monocytes .

    B.. Leptomonad form in female sandfly –

i)                    During blood meal , a sandfly may be infected . The sandfly will draw blood along with the leishmanial forms which are present within the monocytes of an infected person .

ii)                  In midgut of sandfly , the leisshmanial form will change into leptomonad form on the third day of blood meal . Then there will be multiplication and this process will continue upto seven days .

iii)                The flagellates or leptomonad forms then enter to pharynx and buccal cavity of the sandfly . The oesophagus will be completely blocked by flagelets and this will occur between 6^th and 9^th day of blood meal of sandfly . But salivary gland will not be affected .

Clinical features of Kala-azar

a)      Pyrexia – double rise of temperature may be seen .

b)      Enlarged spleen – Characteristic feature

c)      Enlarged liver

d)     General condition of patient  is very poor .

e)      Skin is dry , rough and pigmentation may be present .

f)       Anaemia may be present .