Gequelin LC, Riediger IN, Nakatani SM, Biondo AW, Bonfim CM different EBV concentrations in the cell fraction and plasma.(25,52,53) Two studies comparing detection in WB and plasma concluded that plasma was the best option.(54,55) Niesters et al.(56) verified, in their study, that there is a relationship between DNA present in plasma and EBV-related diseases. Some researchers prefer to work with blood or plasma because mononuclear cells may be difficult to obtain in patients with leukopenia during the first months after transplant.(48,57) Furthermore, in patients that were administered rituximab, the destruction of B cells can affect the number of copies in peripheral lymphocytes.(24) In 24 review studies,(1,27,33,38,45,46,53,54,56-71) the most widely used extraction method was the commercially available QIAamp® DNA Blood Mini Kit (QIAGEN, Hilden, Germany) and the choice real-time quantification system was by hydrolysis probes (TaqMan® probes). Only one of the cited studies did not apply a real-time method.(65) In eight studies, the sample material of choice was WB,(46,61,64,66-70) PBMC was used in five studies(1,45,60,63,65) and plasma or serum in eight.(27,31,53,56-59,62) Two comparative studies were performed,(38,54) one of which between PBMC and plasma - showing higher sensitivity in plasma - and the other between WB and PBMC, showing similar results using both materials. The experiment described by Lay et al.(71) used plasma, WB and PBMC, but without the purpose of comparing sample sensitivity. Final considerations The role of EBV in all of its associated diseases is not yet fully known. Diagnosis and monitoring of these pathologies are of crucial importance for clinical management. Post-transplant EBV monitoring is essential, especially in patients with considerable risk factors. Increased viral load may be an indication of imminent PTLD and prophylactic interventions can prevent or hinder this disease's progression. 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