Title : No cold chain molecular workflow for detecting and differentiating plasmodium
Abstract:
Background
Malaria (or paludism), is a mosquito-borne parasitic disease caused by Plasmodium, is a leading cause of death and disease in many developing countries. The objective of this study was to determine the clinical performance of VIASURE Malaria Real Time PCR Detection Kit and VIASURE Malaria differentiation Real Time PCR Detection Kit using dried blood spot on filter paper samples.
The aim of this retrospective study was to validate and compare the clinical sensitivity and specificity of the VIASURE assays with the reference method used in the laboratory.
Material and methods
The lyophilized Malaria assay and Malaria differentiation assay, which detects the genus Plasmodium spp. and the main human pathogenic Plasmodium species: P. falciparum, P. ovale, P. vivax, P. malariae and P. knowlesi respectively, were used in comparison with an 18S rRNA in-house malaria screening and differentiation assays. A total of 300 blood on filter paper collected from 2016 to 2019, from patients with clinical suspicion of malaria in the Manhiça-Magude district of southern Mozambique were analysed. The DNA extraction was carried out using the Chelex® 100 sodium method and the thermocycler employed was Applied Biosystems 7500 Real-Time PCR System.
Results
A total of 77 samples were considered as Plasmodium spp.-positive by both assays, 1 false positive result and 15 false negative results for VIASURE were obtained and 207 samples showed to be negative for this target by both assays. Regarding species differentiation: VIASURE assay showed 58 true positive and 3 false negative results for P. falciparum, 2 true positive results for P. malariae and 1 true positive and 1 false negative result for P. ovale. After data analysis, the sensitivity and specificity values obtained were:
|
VIASURE target |
Sensitivity |
Specificity |
|
Plasmodium spp. |
0.83 (0.74-0.9) |
0.99 (0.97-1) |
|
P. falciparum |
0.95 (0.86-0.99) |
1 (0.94-1) |
|
P. malariae |
1 (0.15-1) |
1 (0.94-1) |
|
P. ovale |
- |
0.98 (0.91-1) |
This retrospective study demonstrated the good sensibility and specificity of both VIASURE molecular assays using this extraction method on dried blood spots, which is a workflow that does not require a cold chain to be performed.
Audience take away:
- Diagnostic workflow where no cold chain is needed as samples, extraction and RT-qPCR are done with material stored at room temperature.
- Good sensibility and specificity of both VIASURE molecular assays using this extraction method on dried blood spots.
