CMV can be transmitted by multiple routes, mainly by contact in infants and children and by sexual contact in adults. CMV infects a variety of immunologically active cells, including epithelial and mesenteric vascular endothelial cells, T cells, B cells, and NK cells, and replicates in the body after infection, increasing the size of the infected cells and releasing newly synthesized virus to further infect surrounding cells. The infected cells increase in size, have focal necrosis in the center, and release newly synthesized viruses that further infect surrounding cells. The infected cells in the lung tissue are mainly alveolar cells and macrophages, which after infection develop diffuse interstitial lung edema, fibrosis and alveolar swelling, focal necrosis, hemorrhage and hyperplasia, resulting in hypoxemia. CMV infection is particularly severe in patients with cellular immunodeficiency (e.g., post-bone marrow transplantation and AIDS patients) because of the major role of cellular immunity in fighting CMV infection. Since CMV infection is commonly seen in bone marrow and organ transplant patients, it is important to screen donors well before transplantation and try to select CMV antibody-negative donors. For antibody-positive patients, prophylactic treatment with acyclovir can be given one week before and one month after surgery, and an immunoglobulin drip containing highly potent CMV antibodies can be administered 1 day before and 2 weeks after transplantation to improve passive immunity, followed by one dose every 3 weeks until 100 days after surgery. Prevention of CMV pneumonia.