Comparison of three molecular methods for the detection and speciation of Plasmodium vivax and Plasmodium falciparum

Abstract

Background: Accurate diagnosis of Plasmodium spp. is essential for the rational treatment of malaria. Despite its many disadvantages, microscopic examination of blood smears remains the current "gold standard" for malaria detection and speciation. PCR assays offer an alternative to microscopy which has been shown to have superior sensitivity and specificity. Unfortunately few comparative studies have been done on the various molecular based speciation methods.

Natural Plasmodium infection in neotropical primates in the island of São Luís, state of Maranhão, Brazil

“…in samples with very low parasitemia, in which the amount of DNA added to the PCR is close to the detection limit. In these cases, it is likely that the same sample is positive a few times and negative in other reactions (BOONMA et al, 2007). This occurred during the present study, using the PCR protocol proposed by Rubio et al (1999), in which the samples MP28, MP30 and MP37 were amplified in the first genus reaction, but when this was repeated, there was no amplification, even using the same DNA template.…”

Prevalence of Plasmodium falciparum and P. vivax in an area of transmission located in Pará State, Brazil, determined by amplification of mtDNA using a real-time PCR assay

“…Although light microscopy performed under optimal conditions can detect parasitemia as low as 5 parasites/mL (0.0001%) on thick blood smears (Warrell, 2002), molecular assays, particularly those involving qPCR, are well documented to have various advantages over microscopic examination. Compared with the gold-standard nested-PCR assay, qPCR methods have shown high sensitivity (100%) and specificity (100%) for the simultaneous detection of Plasmodium species and have the additional advantage of yielding results in less than 3 h (Perandin et al, 2004;Mangold et al, 2005;Boonma et al, 2007). To bypass one of the main limitations of the standard PCR technique, which is the need for multiple PCR assays on each sample because the target gene is present in only a limited number of copies, Cunha et al (2009) standardized a PCR method to detect P. falciparum and P. vivax through amplification of an mtDNA sequence, which is present in a large number of copies in infected cells.…”

“…Although the qPCR method requires specific material and is more expensive than mi-Prevalence of P. falciparum and P. vivax in Pará State croscopy and conventional PCR (Berry et al, 2005), it presents advantages of rapidity, lower contamination, and better standardization and can be used for routine testing, particularly for the study of populations in endemic areas in which patients may be asymptomatic (Mens et al, 2007;Boonma et al, 2007;Gama et al, 2007;Veron et al, 2009) and in patients who have negative results on routine methods but are strongly suspected of having malaria (Bourgeois et al, 2010). Thus, qPCR assay based on the detection of mitochondrial cytochrome c oxidase genes may be the method of choice for specific situations, including detection in low-parasitized individuals.…”

Trombosis axilar y embolismo pulmonar tras implantación de marcapasos

“…En nuestro caso no se constató trombosis en el electrodo ni en las cavidades cardiacas, sino sólo a nivel de la vena axilar izquierda, relacionado obviamente con el procedimiento de colocación del marcapasos. La existencia de un catéter venoso central, además de ser portador de enfermedades neoplásicas, es el factor de riesgo más invocado para el desarrollo de trombosis venosa y EP en estos pacientes (3)(4)(5)9), no existiendo sin embargo aparente relación entre la localización de la trombosis y la probabilidad de sufrir un EP (5). Estos fenó-menos tromboembólicos pueden aparecer en cualquier momento tras la implantación del marcapasos (2,5,9), si bien un estudio reciente ha encontrado que la mayoría de casos ocurrieron en los primeros 3 meses desde su colocación (4), al igual que en el caso aportado.…”

“…La existencia de un catéter venoso central, además de ser portador de enfermedades neoplásicas, es el factor de riesgo más invocado para el desarrollo de trombosis venosa y EP en estos pacientes (3)(4)(5)9), no existiendo sin embargo aparente relación entre la localización de la trombosis y la probabilidad de sufrir un EP (5). Estos fenó-menos tromboembólicos pueden aparecer en cualquier momento tras la implantación del marcapasos (2,5,9), si bien un estudio reciente ha encontrado que la mayoría de casos ocurrieron en los primeros 3 meses desde su colocación (4), al igual que en el caso aportado. El tratamiento de la trombosis venosa profunda de extremidades superiores y del EP asociado a la implantación de marcapasos puede requerir diferentes medidas como la anticoagulación convencional, trombolisis, angioplastia o cirugía (2,6-8, si bien las últimas publicaciones sobre el tema aconsejan realizar fibrinolisis (6).…”