The Health Significance Of The Diagnosis, Prognosis And Laboratory Investigations Of Visceral Leishmaniasis

Any chronic pyrexial disease occurring in an endemic area associated with hepatosplenomegaly, should raise the possibility of Kala-azar. Diagnosis is confirmed by serology, biochemical tests and demonstration of the parasite. Complement fixation test using an antigen prepared from Kedrowsky’s acid-fast bacillus is positive in 95% case from the third week of illness. Conditions like chronic tuberculosis, lepromatous leprosy, post Kala-azr dermal leishmaniasis and Chaga’s disease may rarely give positive complement fixation test.

Napier’s aldehyde test is a simple bedside test helpful in the diagnosis of chronic kala-azar in dispensary practice. Two drops of commercial formalin (formaldehyde 40%) is added to 1 ml of patient’s serum in a test tube and set aside for 24 hours. In a positive test, the serum solidifies and becomes opaque and white in colour like hard boiled egg-white. The positivity can be graded depending on the speed of the reaction. If gellification occurs within 20 minutes, it is recorded as +++; if within 2 hours, it is recorded as ++; and if after 24 hours, it is taken as +. Positive reaction is diagnostic of Kala-azar in India, especially. In a doubtful case, the serum sets within 24 hours, and it is white in colour but translucent. In such cases, follow-up may be helpful. When the test is negative, the serum remains fluid throughout.

The L.D bodies can be demonstrated microscopically in material obtained by splenic puncture (95%), bone marrow smears (85 to 90%) and in a smaller proportion of liver aspiration smears. They can also be demonstrated in tissue sections by special staining. The parasites can be demonstrated in peripheral blood within monocytes, especially if the buffy coat is examined. The organism can be grown in vitro from bone marrow or spleen puncture aspirate in N.N.N medium.

Differential Diagnosis: All chronic prolonged febrile illnesses and conditions producing hepatosplenomegaly enter the differential diagnosis. Important among these are enteric fever, malaria, acute military tuberculosis, brucellosis, septicemia, hepatic amoebiasis, acute leukemias and lymphoma. In places like India, may places are endemic for malaria and leishmaniasis and these infections therefore can coexist.

Blood: There is moderate anemia with hemoglobin levels around 7 to 9 g/dl. Anemia is due to nutritional deficiency as well as infection. The total leucocyte count is reduced and it varies from 1000 to 3000/cmm, the granulocytes being depressed more. There is relative increase in lymphocytes and monocytes. Most of the cases show thrombocytopenia. Serum proteins show gross alternation. Albumin is lowered and globulins are considerably elevated. IgG and IgM are elevated and C3 complement is low. Advanced cases may show biochemical evidence of hepatic dysfunction.

Complications: Cancrum oris, dysentery, pneumonias, severe anemia, jaundice, hemorrhages and generalized anasarca may develop in untreated cases. Pulmonary tuberculosis may coexist in a few. About 10% of cases may develop cirrhosis of the liver as a late complication after treatment.

Course And Prognosis: If left untreated, the mortality may be as high as 70 to 90% in two years. Death is due to complications like noma, cancrum oris, pneumonia, dysentery and hemorrhages. With prompt therapy, 90% of cases are cured.