Of those with a normal ALT level, significantly more children with IM (97.3%) and atypical EBV infection (91.7%) had an elevated ADA level than those with a respiratory infection (45.8%), malignant disease (57.1%), or other diseases (51.4%) (P < 0.05; Table 3 and Fig. 1). Here, ADA is linked to Epstein-Barr virus infection.