Evaluation of falcivax against quantitative buffy coat (QBC) for the diagnosis of malaria

Introduction: Microscopic detection of appropriately stained blood smear for the diagnosis of Malaria has been the standard diagnostic technique for identifying malaria infections for more than a century. The technique is capable of accurate and reliable identification when performed by skilled microscopists using defined protocols. The problems associated with implementing and sustaining a level of skilled microscopy appropriate for clinical diagnosis have particularly prompted the development of malaria rapid diagnostic devices (MRDDs). The current MRDDs are based on antigen capture immunoassay methodologies using immunochromatographic strip (ICS) technology. The newer generations of MRDDs are using more antigens like Merozoite protein 2 and circumsporozoite proteins. Further these antigens are obtained using recombinant techniques. This study was done for the evaluation of two commercially available immunossays against QBC for the diagnosis of Malaria. Aim of the study: The aim of the study is to evaluate Falcivax (Immunochromatographic Strip) test for the diagnosis of Malaria and to compare with Quantitative Buffy Coat (QBC). Materials & methods: A total of 100 patients attending outpatient department of Kasturba Hospital, Manipal, India, with their own initiative and meeting the inclusion criteria are included in the study. 2ml of blood was collected by venipuncture into tubes (Vacutainer blood collection system) containing EDTA as anticoagulant from all patients. Tests were run in batches of 8 samples at a time for Falcivax, Smear status by QBC, clinical features and relevant laboratory data of each sample was noted down. Results: Out of 100 patients 70 tested positive for malaria by QBC with P. falciparum accounting for 32(45.7%) and P. vivax 37(52.9%). In comparison with the study control - QBC in the detection of malaria, Falcivax test showed sensitivtiy, specificity, positive predictive value and negative predictive value of 90.0%, 100.0%, 100.0% and 81.0% respectively. Conclusion: Falcivax showed a reduced sensitivity compared to the QBC. Hence QBC still continues to be better option than MRDDs for detection of plasmodium infection in health care facilities with all expertise.