Abstract
BACKGROUNDLoa loa is a filarial species found exclusively in West and Central Africa. Microscopy is the traditional diagnosis method for human loiasis. Several molecular methods have developed as an alternative approach for identification of L. loa filarial parasites.OBJECTIVES The aim of this study was to evaluate a Loa-Loop-mediated isothermal amplification (LAMP) assay to diagnose loiasis disease on dried blood spots (DBS) samples, compared to microscopy, filaria-real time-polymerase chain reaction (PCR) and nested-Loa PCR.METHODS A total of 100 DBS samples and 100 blood smears were used for this study. DNA was extracted using saponin/Chelex method. DNA isolated was assayed by a Loa-LAMP assay in parallel to microscopy, filaria-real time PCR and nested-Loa PCR. The sensitivities and specificities of Loa-LAMP assay was computed comparing to each one of the reference methods.FINDINGS Loa-LAMP’s sensitivity was more than 90% and specificity was nearly 100% when compared to molecular methods. On the other hand, sensitivity was decreased a bit when Loa-LAMP faced microscopy, but keeping the other statistical values high.MAIN CONCLUSIONS Loa-LAMP is an appropriate method for loiasis diagnosis in endemic areas. Though, it has disadvantages like the reagents’ high price at the moment and not to be able to detect more filarial species at once.
Highlights
Loa loa is a filarial species found exclusively in West and Central Africa
Seven M. perstans-F-RT-polymerase chain reaction (PCR) positive samples were missed by microscopy, whereas four microscopy positive samples were missed by F-RT-PCR (2 L. loa, 1 M. perstans and 1 mixed infection) (Table II)
The L. loa parasite is no longer as insignificant as it used to be in the past and its growing importance is due to the marked negative effect caused in people who live in co-endemic areas with O. volvulus and W. bancrofti, where mass drug administration is currently underway. [8,18,22] As the goal of ESPEN is to accelerate elimination of the five most prevalent neglected tropical diseases (NTDs) (LF, onchocerciasis, soil-transmitted helminthiases, schistosomiasis and trachoma) accurate L. loa parasite detection is essential for addressing the problem where O. volvulus, W. bancrofti and L. loa infections are co-endemic to achieve global elimination goals for O. volvulus and W. bancrofti.[7,12]
Summary
The aim of this study was to evaluate a Loa-Loop-mediated isothermal amplification (LAMP) assay to diagnose loiasis disease on dried blood spots (DBS) samples, compared to microscopy, filaria-real time-polymerase chain reaction (PCR) and nested-Loa PCR
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