Comparison of the diagnosis of malaria by microscopy, immunochromatography and PCR in endemic areas of Venezuela

Abstract

Whole blood samples (N = 295) were obtained from different locations in Amazonas and Sucre States, in Venezuela. Malaria was diagnosed by microscopy, OptiMAL™ and polymerase chain reaction (PCR), with Plasmodium vivax, P. falciparum, and P. malariae being detected when possible. We identified 93 infections, 66 of which were caused by P. vivax, 26 by P. falciparum, and 1 was a mixed infection. No infection caused by P. malariae was detected. The sensitivity and specificity of each diagnostic method were high: 95.7 and 97.9% for microscopy, 87.0 and 97.9% for OptiMAL, and 98.0 and 100% for PCR, respectively. Most samples (72.2%) showed more than 5000 parasites/µL blood. The sensitivity of the diagnosis by microscopy and OptiMAL decreased with lower parasitemia. All samples showing disagreement among the methods were reevaluated, but the first result was used for the calculations. Parasites were detected in the 6 false-negative samples by microscopy after the second examination. The mixed infection was only detected by PCR, while the other methods diagnosed it as P. falciparum (microscopy) or P. vivax (OptiMAL) infection. Most of the false results obtained with the OptiMAL strip were related to the P. falciparum-specific band, including 3 species misdiagnoses, which could be related to the test itself or to genetic variation of the Venezuelan strains. The use of the microscopic method for malaria detection is recommended for its low cost but is very difficult to implement in large scale, population-based studies; thus, we report here more efficient methods suitable for this purpose.

Performance of rapid DiaMed OptiMal-IT® malaria test in an endemic Ghanaian setting

“…Palmer et al (2003 did not stratify their study population and used the more relevant Polymerase Chain Reaction (PCR) to validate the DiaMed OptiMAL-IT results. Similar results and observations for sensitivity (87.0%) and specificity (97.9%) of DiaMed OptiMAL-IT have been recorded in Venezuela by Rodulfo et al (2007). In the present study, although PCR was not performed, we find the DiaMed OptiMAL-IT antigen assay to have relatively low performance indices, especially for malaria infections with low parasite densities.…”

Detection of Mixed-Species Infections of Plasmodium falciparum and Plasmodium vivax by Nested PCR and Rapid Diagnostic Tests in Southeastern Iran

“…3 Several studies in various parts of the world have revealed the high prevalence of mixed-species infections using PCR. 9,10 Even in very low parasitemia, P. vivax and P. falciparum have been detected using this method.…”

Malaria seroprevalence in blood bank donors from endemic and non-endemic areas of Venezuela

“…We have determined the sensitivity/specificity of the PCR method in the same malaria areas in a previous study (Rodulfo et al 2007a). …”