Several methods based on ELISA, which are easier and faster to perform, have been proposed as alternative methods to distinguish between primary and secondary infections, for example, by measuring IgG antibodies; the avidity titer of IgG; calculating the ratio of IgM/IgG; or the absence of IgG in acute specimens [11, 12, 14, 18, 19]. Here, CD40LG is linked to infection.