Loop-Mediated Isothermal Amplification (LAMP) Assessment for Malaria Diagnosis in Equatorial Guinea

Malaria diagnosis in Equatorial Guinea (EG) is based on conventional microscopy, sometimes combined with rapid diagnostic tests (RDTs). However, some laboratories, such as the Baney Research Laboratory (BRL) have implemented molecular technology for the diagnosis of infectious diseases. This study aimed to evaluate, for the first time in EG, a LAMP method for malaria diagnosis, comparing its performance with conventional microscopy performed in EG and with LAMP and PCR diagnostic methods performed at the National Centre of Tropical Medicine (NCTM), Spain. A total of 178 blood samples (including P. falciparum samples and malaria-negative controls) were evaluated using Dual-LAMP-Pspp and Nested-PCR-Pf in Equatorial Guinea. Dual-LAMP-Pspp performed at the BRL showed sensitivity and specificity values of 97.28% and 100%, respectively, for malaria diagnosis, with no differences between colorimetric and fluorescence-based result readings. Meanwhile, Nested-PCR-Pf showed a sensitivity of 87.07% and a specificity of 100%. Comparison of parasite densities determined by Dual-LAMP-Pspp and conventional microscopy showed a significant moderate negative correlation (correlation coefficient = -0.584). The comparison of Dual-LAMP-Pspp results between BRL and NCTM showed a kappa coefficient of 0.93, whereas the kappa coefficient of the Nested-PCR-Pf assay was 0.70. These findings indicate that Dual-LAMP-Pspp and Nested-PCR-Pf are suitable methods for malaria diagnosis in EG. However, the Dual-LAMP-Pspp assay was easy to perform and interpret and provided results in a shorter time than Nested-PCR-Pf.