Preventive Measures and Diagnosis of Asymptomatic Malaria in Northwest Ethiopia

Background: Asymptomatic malaria poses a huge challenge in meeting the malaria, elimination goal. Due to the poor sensitivity of the common laboratory diagnostic methods of malaria like rapid diagnosis tests (RDTs) and Giemsa stained microscopy, it has often been difficult to detect asymptomatic malaria. Thus, highly sensitive, specific, and field deployable rapid molecular techniques need to be available to accurately detect the disease. This study aimed to assess the application of malaria preventive methods and to assess the prevalence of asymptomatic malaria, using the traditional Giemsa microscopy and molecular methods, such as loop mediated isothermal amplification (LAMP) and nested PCR in the study sites.

Methods: A community based cross-sectional study was conducted from February to May 2014 in North Gondar, Ethiopia. A total of 802 participants were enrolled. Data on socio-demographic profile and associated risk factors for asymptomatic malaria were collected using face-to-face interviews. Capillary blood was collected and blood films and dried blood spots (DBS) were prepared for malaria parasite detection using microscopy, nested polymerase chain reaction (nPCR), and loop-mediated isothermal amplification (LAMP).

Results: In this study, 45.3% of the participants had access to combined universal preventive measures of malaria. LAMP and nPCR were performed for 160 DBS samples. The overall prevalence of asymptomatic malaria detected using Giemsa microscopy, LAMP, and nPCR was 3.75%, 4.375% and 4.375%, respectively.     

Conclusion: A consistent use of the available malaria prevention methods was too limited to produce the intended elimination of malaria in the study area. LAMP was able to identify two extra asymptomatic malaria carriers per 100 study population. This study indicated that an active diagnosis of asymptomatic malaria with molecular techniques, like LAMP, could support malaria elimination through enhanced active case detection. Future studies should evaluate the performance of LAMP and nPCR from fresh blood samples.