Since the 1980’s it is well known that IgM positive test is not enough to assert a primary rubella infection, because some viral infections like Epstein Barr virus infection (EBV), cytomegalovirus (CMV) or human parvovirus B19 (HPV-B19) can cause a cross-reaction with rubella infection [11–16]. Here, CD40LG is linked to Epstein-Barr virus infection.