Molecular detection of human malaria parasites using high resolution melting analysis in Morogoro municipality, Tanzania

Masters Dissertation 2019Microscopy and rapid diagnostic tests (RDTs) are common tools for diagnosing malaria, but are deficient in detecting low Plasmodium parasitaemia and mixed infections. Molecular detection has overcome the limitations by providing greater sensitivity and specificity in Plasmodium species detection. This study was conducted in Morogoro region employing a new molecular diagnostic tool that combines the high sensitivity and specificity of nested PCR (nPCR) and high resolution melting analysis (HRMA). Samples were collected from 301 malaria suspected patients from SUA Health Centre between August-October, 2018 and Sabasaba Health Centre between October-December, 2018. Samples were screened for malaria parasites by microscopy at SUA and mRDTs at Sabasaba, and later analysed by nPCR-HRMA for P. falciparum, P. malariae and P. ovale. Data was analysed using EPI info version 7 and IBM SPSS version 20 software. Sensitivity and specificity of the three diagnostic methods were assessed, variables calculated with 95% confidence interval (CI). Microscopy had a lower sensitivity in diagnosing malaria compared to nPCR-HRMA (p ≤ 0.0361). Among all samples which tested malaria positive by microscopy, only 68.75% were positive by nPCR-HRMA and the rest negative. Similarly, 6.45% samples which were initially found to be malaria negative by microscopy were positive by nPCR-HRMA. Most of the results from mRDTs were in agreement with nPCR-HRMA results (p ≤ 0.2987). Among the samples which tested positive by mRDT, 83% were also positive by nPCR-HRMA while only 1.9% of the samples which had tested negative by mRDT were positive by nPCR-HRMA. In addition nPCR-HRMA provided accurate diagnosis of infecting single or mixed Plasmodium species in samples that were missed by mRDT and microscopy. Deployment of improved malaria diagnostic methods like the nPCR- HRMA might help in improvement and better understanding of the epidemiology of Plasmodium species, with a particular focus on identifying asymptomatic carriers and for designing appropriate treatment