Cytomegalovirus (CMV) is characterized by the formation of large type A eosinophilic intranuclear and intracytoplasmic inclusion bodies in infected cells leading to viral pneumonia. Most are asymptomatic occult infections, but in immunocompromised and infants can cause severe lung infections leading to death. In recent years with the introduction of bone marrow and organ transplants and the increasing number of AIDS patients, CMV has become the most common causative agent in both conditions. Cytomegalovirus belongs to group B herpes viruses, and CMV infection is strictly species-specific. Humans are infected only by human cytomegalovirus, and the infected virus grows and multiplies slowly in the cells (2 to 3 months to show obvious lesions). Infected cells have enlarged nuclei and increased cytoplasm, forming typical eosinophilic intranuclear and intracytoplasmic inclusion bodies. The occurrence of CMV infection after organ transplantation is associated with the following factors: ① CMV-negative recipients (R-) receiving organs from CMV-positive donors (D+), also known as primary infection. ② Recipients who are preoperatively CMV-positive (R+), reignition of CMV infection occurs when the endogenous latent virus is reactivated. Approximately 75% of transplant recipients have a positive pre-transplant serum test result. (iii) The recipient is fed CMV-positive blood. ④Recipients treated with hormonal shock therapy or with monoclonal or polyclonal anti-lymphocyte antibodies due to acute rejection. ⑤ Immunosuppressive regimens are also associated with the incidence of CMV infection. The incidence is 10-15% if cyclosporine A or tacrolimus, azathioprine and prednisone regimens are applied; 25-30% if anti-lymphocyte antibodies are applied for immune induction therapy; and 50-60% if anti-rejection therapy with anti-lymphocyte antibodies is administered. Clinical manifestations The main manifestation of CMV infection is fever, usually accompanied by loss of appetite, malaise, myalgia, arthralgia and uncommon (5-10%) atypical lymphocytosis and moderate granulocytopenia. There are clinical manifestations depending on the site of infection, the more common being the lungs and liver. CMV pneumonia is one of the common clinical manifestations and is interstitial pneumonia, often subacute and nonspecific, with symptoms lasting 1 to 4 weeks, and in the event of alveolar hemorrhage symptoms can last 1 to 3 months, with some patients progressing to respiratory failure within 1 week. The clinical manifestations mainly include fever, dry cough, chest tightness and shortness of breath, dyspnea, increased heart rate and hypoxemia, etc. In a few patients, dry or wet woven woven CMV pneumonia can be heard in the lungs. The most common signs are bilateral interstitial infiltrative lesions, hairy glass-like changes, reticular changes and nodular changes, and in a few patients, bilateral solid lung changes and pleural effusion. Prevention and treatment of CMV infection There is a consensus among scholars in China and abroad that prevention of CMV infection is important. One of the most important methods is the prophylactic use of antiviral drugs. All transplant recipients receive antiviral therapy after surgery and stop treatment at a predetermined endpoint, with the aim of preventing CMV replication and infection and preventing CMV disease. The current drug commonly used to prevent CMV infection is ganciclovir, the main side effects of which are renal damage and bone marrow suppression. CMV infection is most likely to occur within six months after transplantation, and the usual duration of use of ganciclovir to prevent infection is recommended to be at least 3 months. Currently, there is a trend towards a later duration of CMV infection, and therefore the duration of ganciclovir dosing is sometimes adjusted to 6 months.