Field evaluation of malaria malachite green loop-mediated isothermal amplification in health posts in Roraima state, Brazil

Heather M Kudyba; Jaime Louzada; Dragan Ljolje; Karl A Kudyba; Vasant Muralidharan; Joseli Oliveira-Ferreira; Naomi W Lucchi

doi:10.1186/s12936-019-2722-1

Field evaluation of malaria malachite green loop-mediated isothermal amplification in health posts in Roraima state, Brazil

Malar J. 2019 Mar 25;18(1):98. doi: 10.1186/s12936-019-2722-1.

Authors

Heather M Kudyba¹, Jaime Louzada², Dragan Ljolje³, Karl A Kudyba¹, Vasant Muralidharan⁴, Joseli Oliveira-Ferreira^{5

6}, Naomi W Lucchi⁷

Affiliations

¹ Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, USA.
² Federal University of Roraima, Boa Vista, Roraima, Brazil.
³ Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA.
⁴ Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, USA. [email protected].
⁵ Federal University of Roraima, Boa Vista, Roraima, Brazil. [email protected].
⁶ Institute Oswaldo Cruz-Fiocruz, Rio de Janeiro, Brazil. [email protected].
⁷ Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA. [email protected].

Abstract

Background: Microscopic detection of malaria parasites is the standard method for clinical diagnosis of malaria in Brazil. However, malaria epidemiological surveillance studies specifically aimed at the detection of low-density infection and asymptomatic cases will require more sensitive and field-usable tools. The diagnostic accuracy of the colorimetric malachite green, loop-mediated, isothermal amplification (MG-LAMP) assay was evaluated in remote health posts in Roraima state, Brazil.

Methods: Study participants were prospectively enrolled from health posts (healthcare-seeking patients) and from nearby villages (healthy participants) in three different study sites. The MG-LAMP assay and microscopy were performed in the health posts. Two independent readers scored the MG-LAMP tests as positive (blue/green) or negative (clear). Sensitivity and specificity of local microscopy and MG-LAMP were calculated using results of PET-PCR as a reference.

Results: A total of 91 participants were enrolled. There was 100% agreement between the two MG-LAMP readers (Kappa = 1). The overall sensitivity and specificity of MG-LAMP were 90.0% (95% confidence interval (CI) 76.34-97.21%) and 94% (95% CI 83.76-98.77%), respectively. The sensitivity and specificity of local microscopy were 83% (95% CI 67.22-92.66%) and 100% (95% CI 93.02-100.00%), respectively. PET-PCR detected six mixed infections (infection with both Plasmodium falciparum and Plasmodium vivax); two of these were also detected by MG-LAMP and one by microscopy. Microscopy did not detect any Plasmodium infection in the 26 healthy participants; MG-LAMP detected Plasmodium in five of these and PET-PCR assay detected infection in three. Overall, performing the MG-LAMP in this setting did not present any particular challenges.

Conclusion: MG-LAMP is a sensitive and specific assay that may be useful for the detection of malaria parasites in remote healthcare settings. These findings suggest that it is possible to implement simple molecular tests in facilities with limited resources.

Keywords: Diagnosis; Malachite green loop-mediated isothermal amplification; Malaria; Plasmodium.

MeSH terms

Brazil
Humans
Malaria, Falciparum / diagnosis*
Malaria, Vivax / diagnosis*
Nucleic Acid Amplification Techniques / instrumentation
Nucleic Acid Amplification Techniques / methods*
Plasmodium falciparum / isolation & purification*
Plasmodium vivax / isolation & purification*
Population Surveillance / methods*
Rosaniline Dyes / chemistry*
Sensitivity and Specificity

Substances

Rosaniline Dyes
malachite green

Abstract

MeSH terms

Substances

Grants and funding