CD40LG and cytomegalovirus infection: One large single-center prospective case-control study observed patients with acute CMV infection and matched CMV IgM negative controls for 6 months and found 3.06 cases of acute VTE per 1000 in those with positive IgM compared to 1.36 cases of acute VTE per 1000 in those with negative IgM (OR = 2.25, 95% CI 1.38-3.66, p = 0.003) [6].