Comparative Study of Peripheral Blood Smear, Modified Centrifuged Blood Smear And Dipstick Method In Diagnosis of Malaria With Evaluation of Hematological Parameters

Abstract

Nonspecific clinical presentation of malaria leads to overtreatment in endemic areas and missing the diagnosis in low transmission areas. The Peripheral Blood smear is an established method in malaria diagnosis. However low sensitivity, cumbersome technique and need for specially trained persons for interpretation limits its usefulness. The antigen detection method is highly sensitive and specific method, however mixed cases have to be confirmed on smears and quantification of parasitemia cannot be done, also it involves high cost. This study aims to establish Modified Centrifuged Blood Smear (MCBS) as a sensitive, specific and cost effective technique in malaria diagnosis. Also we aim to detect if presence of certain haematological indices would increase the probability of malaria in patients with acute febrile illness. Presence of such an indicator would prompt a more diligent search for malarial parasite and prompt institution of specific therapy. Materials and methods: 328 patients with symptoms suspicious of malaria were taken as cases. 200 others with no clinical suspicion of malaria acted as controls. Venous blood was collected and subjected to three techniques for diagnosis of malaria; Peripheral Blood Smear examination (PBS), Modified Centrifuged Blood Smear (MCBS) and Antigen detection (dipstick method). The blood was also subjected to analysis of Haemoglobin (Hb) value, Total WBC count (WBC), Platelet count, Differential count (DC) and Red cell Distribution Width (RDW). Results: Modified Centrifuged Blood Smear method (MCBS) improves the sensitivity of peripheral blood smear method without compromising on specificity. Out of the haematological parameters assessed in this study, thrombocytopenia and anaemia were found to be indicators of malaria. Conclusion: Use of MCBS in place of PBS will eliminate a lot of false negatives; also it is cost effective and requires no special training. Thrombocytopenia and anaemia have a strong association with malaria. Presence of these parameters in a clinically suspicious case should alert the clinician for the presence of malaria.