Performance of a new gelled nested PCR test for the diagnosis of imported malaria: comparison with microscopy, rapid diagnostic test, and real-time PCR

Abstract

Microscopy and rapid diagnostic tests (RDTs) are the techniques commonly used for malaria diagnosis but they are usually insensitive at very low levels of parasitemia. Nested PCR is commonly used as a reference technique in the diagnosis of malaria due to its high sensitivity and specificity. However, it is a cumbersome assay only available in reference centers. We evaluated a new nested PCR-based assay, BIOMALAR kit (Biotools B&M Labs, Madrid, Spain) which employs ready-to-use gelled reagents and allows the identification of the main four species of Plasmodium. Blood samples were obtained from patients with clinical suspicion of malaria. A total of 94 subjects were studied. Fifty-two (55.3%) of them were malaria-infected subjects corresponding to 48 cases of Plasmodium falciparum, 1 Plasmodium malariae, 2 Plasmodium vivax, and 1 Plasmodium ovale. The performance of the BIOMALAR test was compared with microscopy, rapid diagnostic test (RDT) (BinaxNOW® Malaria) and real-time quantitative PCR (qPCR). The BIOMALAR test showed a sensitivity of 98.1% (95% confidence interval [CI], 89.7-100), superior to microscopy (82.7% [95% CI, 69.7-91.8]) and RDT (94.2% [95% CI, 84.1-98.8]) and similar to qPCR (100% [95% CI, 93.2-100]). In terms of specificity, the BIOMALAR assay showed the same value as microscopy and qPCR (100% [95% CI, 93.2-100]). Nine subjects were submicroscopic carriers of malaria. The BIOMALAR test identified almost all of them (8/9) in comparison with RDT (6/9) and microscopy (0/9). In conclusion, the BIOMALAR is a PCR-based assay easy to use with an excellent performance and especially useful for diagnosis submicroscopic malaria.

Performance evaluation of different strategies based on microscopy techniques, rapid diagnostic test and molecular loop-mediated isothermal amplification assay for the diagnosis of imported malaria

“…In this respect, microscopic diagnosis alone (TkS or QBC with TnS) remains a frequently used strategy in France for malaria diagnosis [6]. However, as observed in our study, its sensitivity is thought to be no higher than 90% in nonendemic countries when compared to PCR [14,23], and it depends on infecting species, geographic origin and the microscopist's experience [23], which can be limited in nonendemic regions. A study by the French National Reference Centre for Malaria showed that 43.7% of 986 city and hospital medical laboratories did not have any cases of malaria in a year [21].…”

The effectiveness of microscopy: Rapid diagnostic test and molecular assay in diagnosing malaria.

“…This method has been in use for century and has been the main tool for diagnosis of malaria in laboratories [7]. This method is relatively simple and requires less training of the microscopists; with an average sensitivity of about 50-100 parasites per microliter of blood [8,9]. Also, this method detects different species of Plasmodium in specimens.…”

“…Currently, this method is increasingly in use for diagnosis of malaria parasite due to the fact that it is rapid, easy to use and does not require much training or special equipment [10]. However, there are limitations to the use of this method because the method is not sensitive to identify different species of Plasmodium and the low sensitivity to detect parasitemia, if the intensity is less than 100 parasites per microliter of blood [11,9]. Molecular technique of detecting malaria parasite is a very sensitive and accurate method of malaria diagnosis.…”

Development of an Immunosensor for PfHRP 2 as a Biomarker for Malaria Detection

“…These methods have a specific use, as they are limited to the measurement of past exposure to the disease. Methods based on parasite nucleic acid detection [ 11 ] have shown great sensitivity and specificity, but require significant infrastructure and training, and are more expensive than the blood smear method [ 12 ]. Methods based on the use of antibodies to recognise parasite components or biomarkers have also emerged in recent years [ 13 ].…”