Early and adequate malaria diagnosis is critical to opportune and effective treatment to prevent clinical complications and death. Among the malaria diagnostic tools currently available, microscopic examination of TBS remains the gold standard for defining malaria infection, not only because of the relative ease and low cost, but also for its ability to provide a quantitative result. Malaria RDTs are particularly useful in remote areas of difficult access and lack of basic infrastructure required in a microscopy post. The interpretation of two test lines contained in the RDT may be challenging from the point of view of personnel with low level of education, training and supervision (i e, community health workers) located in remote rural areas. Although the SD Bioline Malaria Antigen Pf/Pv RDT imposes this difficulty, it was decided to use this RDT in combination with the Deki Reader due to the known presence of both parasite species in the study areas. A previous study conducted in rural health facilities in Tanzania demonstrated that interpretation of SD Bioline Malaria Ag Pf/Pan RDT by Deki Reader is substantially equivalent to that of visual interpretation as performed by laboratory technicians with vast experience in RDT processing and interpretation , suggesting that a device such as the Deki Reader can be used in routine care for interpretation of RDT with high-quality diagnostic results at POC.
In the present study, the performance of the Deki Reader interpreting SD Bioline Pf/Pv RDTs was at least as good as the visual interpretation by experts, with sensitivity, specificity, positive and negative predictive value similar to visual interpretation of the same RDT (Tables 2 and 3). There was no statistically significant difference between the diagnostic accuracy of the Deki Reader and the visual interpretation of RDTs (Fisher’s exact test).
Important differences in the accuracy of the Deki Reader were identified when microscopy was used as the gold standard for malaria diagnosis. Most of the RDT-positive/microscopy-negative discordance is likely due to reduced specificity as result of the persistent antigenaemia of P. falciparum for approximately two weeks after parasite clearance  and most of microscopy-positive/RDT-negative cases might have originated in deficiencies in the microscopy test.
Similar findings to the present study with respect to comparative performance of microscopy versus RDTs have been reported previously [30–35], and the sensitivity and specificity of the RDTs with this reference test were in agreement with previous reports, including the third evaluation round of FIND . In the same way, other studies using microscopy corrected by PCR suggested that RDTs may actually be more sensitive than expert slide reading . However, RDTs are not able to replace microscopy as the gold standard for malaria diagnosis, they can be used as complementary technique in situation where experienced personnel are not available, in order to perform a rapid diagnosis, which can a few hours later be confirmed or corrected by microscopy or PCR.
The areas selected for this study, although distant from main cities of Colombia, benefit from electricity, basic laboratory facilities and are reachable by road. They all had sufficient conditions for proper storage of the test kits. Deki Reader batteries could be recharged easily when needed and communication infrastructure for mobile and land telephone were both available.
TBS microscopy presented serious limitations, with factors such as variability in techniques of blood film preparation, staining, reading standards, and most importantly, highly dependent on the level of expertise of microscopists. In the present study, laboratory technicians had training and experience above the standard level of field microscopist. Despite their university training, the significant loss of information for the final analysis (384 = 17.5%), most of which (238 = 10.8%) presented major violation of RDT manufacturer’s recommendation, indicated that although constant monitoring was available, the two-day training may have been insufficient. The PI and study coordinators had permanent access to the database via internet portal especially designed for the study and were able to monitor the progress of the study and to review images of the RDTs which allowed them to redirect training efforts to the areas where images suggested RDT mishandling. Device users in the field were able to perform the data collection using the touch screen and processing and interpretation of RDTs without major problems. Likely, due to software malfunction early in the course of the study, data from 37 samples (1.7%) were not recorded in the device nor transmitted to the database.
Although some places in remote endemic regions do not yet have reliable mobile phone connectivity, the device saves all data which can be transmitted later under good connections to mobile networks. The data and images displayed in the portal created for this study allowed to follow up closely the performance of field operators. It has also demonstrated the potential to be greatly beneficial to health programme managers by providing a tool to perform remote QA monitoring of field activities. The ability to assist in POC diagnosis, and simultaneously capture and make immediately available pivotal epidemiological data at source of origin makes this a very attractive tool to enhance epidemiological surveillance, strengthen health care systems, and contribute to global mapping efforts of malaria and other infectious diseases [37–39]. The information collected, along with the correspondent RDT image, was sent immediately from remote areas to a database, being part of the Fio Cloud services with 100% fidelity.
Although the function of the Deki Reader is to interpret the presence or absence of a test line signal, independent of the analyses that are finally deposited on it, these results could not be extrapolated to other RDTs. Important differences in RDT clinical diagnostic performance have been well documented, and therefore the results presented here are only applicable to SD Bioline Malaria Antigen Pf/Pv RDT. Nevertheless, the performance of the Reader should be independent to the underlying immunochemistry and thus should provide similar performance characteristics for other RDTs using the same immunochromatographic test.