Foldscope: Diagnostic Accuracy and Feasibility of its Use in National Malaria Control Program

Malaria has been an important public health all over the globe. Although conventional light microscopy is the gold standard of diagnosis, light microscopes are heavy, fragile, costly, and electricity dependent. Rapid diagnostic tests (RDTs) have become more popular but perform badly in temperate climate. This is because the RDT kits require maintenance of cold chain for its optimal use. In this regard, there is a recent interest in handheld malaria microscopy at the point of care in the field setting. Foldscopes are cheap, handy, nonfragile, and use mobile camera for illumination. The purpose of the study was to find whether foldscope can be used in the national vector borne disease control program (NVBDCP) in India.

Ten laboratory technicians were trained in identifying malaria parasites using foldscope and their mobiles. Later, they were provided with unassembled foldscope to document their test results for the preidentified malaria slides. The blood smears were stained as per the protocol of NVBDCP. The report of the index test (foldscope microscopy) was compared with the reference test (conventional microscopy).

The sensitivity and specificity of the index test was found to be 13.3% (6.257-26.18), specificity of 97.78% (88.43-99.61), positive predictive value 85.71% (48.69-97.43), and negative predictive value 53.01% (42.38-63.38). The devise failure rate and test failure rate were 20% and 11.7%. The kappa agreement between the index and reference microscopy was only 11% and the McNemar P < 0.01.

The ×400 foldscope at its present magnification and illumination cannot be utilized in the field under NVBDCP.