Sensitivity of microscopy compared to molecular diagnosis of &lt;i&gt;P. falciparum&lt;/i&gt;: Implications on malaria treatment in epidemic areas in Kenya

Wangai, Laura Nyawira; Karau, Muriira Geoffrey; Njiruh, Paul Nthakanio; Sabah, Omar; Kimani, Francis; Magoma, Gabriel; Njagi, Kiambo

doi:10.4314/ajid.v5i1.66504

Cited by 36 publications

(31 citation statements)

References 13 publications

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“…Similarly, PCR estimated higher prevalence values for the species evaluated and for certain types of co-infection, such increases having been observed in previous studies for both simple and mixed infections [22, 23, 27, 47, 48]. This result highlights PCR’s potential for confirming a clinical suspicion of malaria, in spite of being expensive and not available in health centres having limited resources [61]. This study has thus confirmed the importance of PCR-based diagnosis as the norm in future studies concerning P. malariae epidemiology [19, 36, 48, 53].…”

Section: Discussionsupporting

confidence: 76%

Plasmodium malariae in the Colombian Amazon region: you don’t diagnose what you don’t suspect

Niño

Cubides

Camargo-Ayala

et al. 2016

Malar J

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BackgroundMalaria is a worldwide public health problem; parasites from the genus Plasmodium spp. are the aetiological agent of this disease. The parasite is mainly diagnosed by microscope-based techniques. However, these have limited sensitivity. Many asymptomatic infections are sub-microscopic and can only be detected by molecular methods. This study was aimed at comparing nested PCR results to those obtained by microscope for diagnosing malaria and to present epidemiological data regarding malaria in Colombia’s Amazon department.MethodsA total of 1392 blood samples (taken by venepuncture) from symptomatic patients in Colombia’s Amazon department were analysed in parallel by thick blood smear (TBS) test and nested PCR for determining Plasmodium spp. infection and identifying infecting species, such as Plasmodium vivax, Plasmodium malariae and/or Plasmodium falciparum. Descriptive statistics were used for comparing the results from both tests regarding detection of the disease, typing infecting species and their prevalence in the study region. Bearing the microscope assay in mind as gold standard, PCR diagnosis performance was evaluated by statistical indicators.ConclusionThe present study revealed great differences between both diagnostic tests, as well as suggesting high P. malariae prevalence from a molecular perspective. This differed profoundly from previous studies in this region of Colombia, usually based on the TBS test, suggesting that diagnosis by conventional techniques could lead to underestimating the prevalence of certain Plasmodium spp. having high circulation in this area. The present results highlight the need for modifying state malaria surveillance schemes for more efficient strategies regarding the detection of this disease in endemic areas. The importance of PCR as a back-up test in cases of low parasitaemia or mixed infection is also highlighted.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1629-3) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 76%

Plasmodium malariae in the Colombian Amazon region: you don’t diagnose what you don’t suspect

Niño

Cubides

Camargo-Ayala

et al. 2016

Malar J

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“…Two studies compared PCR on DBS against liquid whole blood and found a lower sensitivity, particularly for samples with low parasitaemia55,56 (Table 3). DBS PCR compared with microscopy achieves comparable performance or in some studies, is more sensitive 57. However, DBS PCR has a lower sensitivity than PCR on whole blood.…”

Section: Resultsmentioning

confidence: 96%

An Overview of the Clinical Use of Filter Paper in the Diagnosis of Tropical Diseases

Smit¹,

Elliott²,

Peeling³

et al. 2014

The American Society of Tropical Medicine and Hygiene

116

114

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Tropical infectious diseases diagnosis and surveillance are often hampered by difficulties of sample collection and transportation. Filter paper potentially provides a useful medium to help overcome such problems. We reviewed the literature on the use of filter paper, focusing on the evaluation of nucleic acid and serological assays for diagnosis of infectious diseases using dried blood spots (DBS) compared with recognized gold standards. We reviewed 296 eligible studies and included 101 studies evaluating DBS and 192 studies on other aspects of filter paper use. We also discuss the use of filter paper with other body fluids and for tropical veterinary medicine. In general, DBS perform with sensitivities and specificities similar or only slightly inferior to gold standard sample types. However, important problems were revealed with the uncritical use of DBS, inappropriate statistical analysis, and lack of standardized methodology. DBS have great potential to empower healthcare workers by making laboratory-based diagnostic tests more readily accessible, but additional and more rigorous research is needed.

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“…Such diagnostic constraints of microscopy and RDT have serious implications for malaria control in the country. Studies have shown that a missed diagnosis of falciparum malaria increases the risk of complicated or severe disease [ 43 , 44 ]. A missed diagnosis of P. vivax concurrent with P. falciparum is even more problematic since this species could cause relapses, thereby compounding morbidity.…”

Section: Discussionmentioning

confidence: 99%

Microscopic and molecular evidence of the presence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in an area with low, seasonal and unstable malaria transmission in Ethiopia

et al. 2015

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BackgroundThe presence of asymptomatic infections has serious implications for malaria elimination campaigns. Since asymptomatic carriers do not seek treatment for their infection and may become gametocyte carriers, they undoubtedly contribute to the persistence of malaria transmission in a population. The presence of asymptomatic parasitemias was noted in areas with seasonal malaria transmission. In Ethiopia there is a paucity of data regarding the prevalence of asymptomatic malaria carriage. This study was undertaken to assess the presence and prevalence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in south-central Oromia, Ethiopia.MethodsA total of 1094 apparently healthy individuals ≥ 2 years of age in south-central Oromia, Ethiopia, an area with seasonal and unstable malaria transmission, were screened for the presence of asymptomatic plasmodial infections. Finger-prick blood samples were taken from each participant for blood film preparation for microscopy and the rapid diagnostic test (RDT). Blood samples were also spotted on Whatman 3MM filter paper for parasite DNA extraction.ResultsThe prevalence of asymptomatic Plasmodium carriage (P. falciparum, P. vivax and mixed species) was 5.0 % (55/1,094) as determined by microscopy, while the prevalence as determined using RDT was 8.2 % (90/1,094). PCR was done on 47 of 55 microscopy-confirmed and on 79 of 90 RDT-confirmed samples. PCR detected parasite DNA in 89.4 % (42/47) of the microscopy-positive samples and in 77.2 % (61/79) of the RDT-positive samples. No significant difference was observed in the prevalence of asymptomatic P. falciparum or P. vivax infections in the study area (P > 0.1). However, the prevalence of asymptomatic parasitaemia was significantly associated with gender (OR = 0.47, P = 0.015; being higher in males than females) and age (X2 = 25, P < 0.001; being higher in younger than in older individuals). Age and parasite densities had an inverse relationship.ConclusionsThis study confirms the presence of asymptomatic P. falciparum and P. vivax infections in south-central Oromia, an area with low, seasonal and unstable malaria transmission in Ethiopia. Of 55 microscopically confirmed asymptomatic infections, P. falciparum monoinfection accounted for 45.5 % and of 90 RDT positive asymptomatic infections, 66.7 % were P. falciparum. Although not statistically significant, P. falciparum accounted for a relatively large number of the asymptomatic infections as determined by both tests. The prevalence of asymptomatic parasitaemia was highest in the younger age group. HRP-2-based RDTs specific for P. falciparum showed high false positivity rate compared to Plasmodium lactate dehydrogenase (pLDH) specific to P. vivax. Although microscopy and RDT detected substantial numbers of asymptomatic infections in apparently healthy inhabitants, the use of a highly sensitive molecular diagnostics offers a more accurate assessment of the magnitude of asymptomatic infections.

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Sensitivity of microscopy compared to molecular diagnosis of <i>P. falciparum</i>: Implications on malaria treatment in epidemic areas in Kenya

Cited by 36 publications

References 13 publications

Plasmodium malariae in the Colombian Amazon region: you don’t diagnose what you don’t suspect

Plasmodium malariae in the Colombian Amazon region: you don’t diagnose what you don’t suspect

An Overview of the Clinical Use of Filter Paper in the Diagnosis of Tropical Diseases

Microscopic and molecular evidence of the presence of asymptomatic Plasmodium falciparum and Plasmodium vivax infections in an area with low, seasonal and unstable malaria transmission in Ethiopia

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