Portable device to analyze thick blood smears for malaria diagnosis in field laboratories

A timely diagnosis and immediate effective treatment are the bases for the management of malaria to reduce the morbidity and mortality caused by this disease (OMS, 2016; WHO, 2018b). Malaria turns out to be one of the most serious public health problems in the world. According to the World Health Organization-WHO (2016), in 2017, 219 million cases of malaria were estimated worldwide. Parasitological diagnosis of malaria is routinely made in the laboratory. Microscopy diagnostic procedure is considered the "Gold Standard"(INS, 2010). This is because, in addition to its economic advantage, it also permits to monitor the patient¿s response to treatment, by means of the analysis of parasitic density in samples taken before and after the treatment. However, the quality of this technique is often inadequate due to factors such as the limited availability of materials and time in patient care, and the conditions and place of sample preparation (WHO, 2016a)(WHO, 2016b). In Colombian territorial subdivisions such as Antioquia, every 21 minutes there is a new case of malaria. This situation is also found in other regions (ColPrensa, 2013). Most of those cases are diagnosticated in health posts in remote rural areas (see Figure. 1). There, patients must deal with geographical limitations (rough terrain and distances), civil violence, and difficult climate conditions, among other factors. These conditions affect the dynamics of rural health posts, which have to streamline the process, dealing in short time with all the cases (conducting fast sample preparation, and fast and accurate diagnosis) (Ospina et al., 2016) . Particularly, the dexterity of technicians in the whole process is critical. In Panamerican Health Organization , cases of false positives (28.6%) and false negatives (38.1%) have been found (OPS, 2018). This results probably because the preparation and coloration of the sample. Those results agree to a similar study carried out in 2017 to 77 laboratories in Colombia (Disan, 2018). Besides the technician experience, the quality of the coloration in thick blood smears is also crucial to achieve an optimal diagnosis (WHO, 2010; World Health Organization, 2018). Malaria diagnosis takes around one hour from the moment the sample is taken until a diagnosis is provided. This time includes around 35 minutes for the preparation of the smear (drying and colorant application), and between 15-30 minutes to analyze the blood smear. In presence of a diagnosis with high uncertainty, due to an error in the process plus the low sensibility and accuracy of the microscopy, the sample must be retaken or sent to a reference lab. However, delay in proper treatment is associated with increased complications and mortality in patients with malaria (Campuzano Zuluaga & Blair Trujillo, 2010),}