1, mother-child CMV-IgG titer comparison is only applicable to small infants, >6 months old infants have little possibility of fetal transmission of antibodies and may not be considered. 2, CMV activation criteria for infection: blood CMV-PP65 antigen (+), blood CMV-DNA fluorescence quantification ≥ E+04 copies/ml or a short-term increase in blood fluorescence quantification ≥ E+02 copies/ml, where CMV-PP65 antigen specificity is 90% or more. The reason why CMV-IgM is not counted is that ① in small infants, especially those younger than 6 months, CMV-IgM often shows (-); ② herpesvirus infections of the same genus can also show false (+) due to cross-reactivity; ③ CMV-IgM can persist (+) for several months after CMV changes from an activated to a latent infection. CMV-IgG(-)/CMV-IgM(+), which is a recent primary infection, can be considered as an activated infection. Urinary CMV-DNA fluorescence quantification can be used as a basis for the diagnosis of CMV infection and is not suitable for judging whether the infection is activated. 3, CMV activation infection, need to check the organ function examination, immune function examination and recommended to improve the rehabilitation department of brain injury evaluation; organ function examination including BAEP, fundus examination, head CT, blood routine (whether ITP, etc.), liver function, which is the most common organ system involved in CMV infection. It is best if evidence of CMV activity can be detected by biopsy (liver biopsy, bone marrow examination, intestinal tissue biopsy, etc.), but this is basically impossible in the current medical environment. In addition, pneumonia, hemorrhagic enteritis, epilepsy, etc., which are poorly treated, should also be considered as CMV infections, and relevant tests should be performed and anti-CMV treatment should be considered. Immune function tests include immune panel (humoral immunity) and lymphocyte immunophenotyping (cellular immunity). 4, treatment principles: ① CMV must be the activation phase; ② there is organ function damage (excluding other causes) or immune function is significantly low. 2 at the same time can be anti-CMV treatment. Because ganciclovir treatment of CMV infection also only inhibits the virus and does not clear it; in other words, it reduces CMV from an activated infection to a latent infection. If the CMV infection is latent, even with organ function damage, the use of ganciclovir is meaningless, and there is little literature to suggest that ganciclovir improves organ function damage; in addition, even if CMV is an activated infection, without causing organ function damage, we do not recommend the use of ganciclovir as long as immune function is basically normal, as opposed to the greater side effects of ganciclovir (especially in pediatric patients), and only Short-term review and regular follow-up. We also recommend “preemptive therapy” for CMV-activated infections where immune function is significantly low, such as in primary and secondary immunodeficiency diseases, long-term use of immunosuppressive drugs, organ transplantation, or autoimmune diseases, because CMV can easily cause damage to the body. In short, CMV infection does not require treatment, but at least 90% of cases do not require treatment according to the CDC. 5.Treatment plan: ①induction therapy: ganciclovir 5mg/kg.times, Q12H, intravenous infusion*2 weeks ②maintenance therapy: ganciclovir 5mg/kg.times, QD, intravenous infusion*2 weeks-4 weeks. Pay attention to the simultaneous rehepatic treatment; check blood routine and liver function weekly, and generally recheck blood CMV-PP65 antigen and blood CMV-DNA fluorescence quantification at the end of the second and fourth week of treatment. 6.Efficacy evaluation: blood CMV-PP65 antigen turn(-) or blood CMV-DNA fluorescence quantification copy number decrease is considered effective; otherwise, it is considered resistant or ineffective, and may need to extend the course of treatment. 7.Discontinuation indications: If the blood CMV-PP65 antigen (-) and blood CMV-DNA fluorescence quantification are basically normal for 2 consecutive times during the course of treatment, we can refer to the improvement of organ function damage, and recommend specialist consultation for organ function damage such as hearing damage. 8, follow-up matters: we believe that regular follow-up is needed within 3 years of age, BAEP, fundus examination, etc. even if the first time normal need to be regularly reviewed (first time, 6 months, 1 year, 2-3 years). 9.The above is only the majority of cases, there are other possible cases, need to grasp the principle, specific analysis of specific problems.