CMV pneumonia

　　The pathogen of CMV pneumonia belongs to the B group of herpesviruses, which is a double-stranded DNA virus with an envelope and a spherical nucleus. CMV is unstable in heat and low temperature, and can be inactivated at 56℃ for 30 minutes or at 4℃ for a week, as well as by ultraviolet light and liposoluble solvents. CMV has two antigens, complement binding antigen and neutralizing antigen. The former mostly exists in the form of soluble antigen, while the latter is mainly composed of glycoproteins, which are one of the components of the viral envelope. CMV infection has strict species specificity, and humans are only infected with human CMV. After infection, the virus grows and reproduces slowly in cells (manifesting obvious lesions in 2 to 3 months), and the nucleus of the infected cell becomes larger, the cytoplasm increases, and typical eosinophilic intranuclear and cytoplasmic inclusions are formed.

　　Most CMV (cytomegalovirus) infected individuals with good immune function show asymptomatic latent infection. Due to the low immunity of patients with CMV pneumonia, they are prone to concurrent bacterial or fungal infections.

　　Most CMV (cytomegalovirus) infected individuals with good immune function show asymptomatic latent infection, thus becoming a source of infection for CMV in bone marrow and organ transplant recipients. Therefore, it is very important to perform CMV serological tests on donors before transplantation. The clinical manifestations of CMV pneumonia after transplantation include the following:

　　1. Acute progressive type
　　Fever, cough, dyspnea, shortness of breath after activity, hypoxia, and respiratory failure may occur within 1 to 2 months after transplantation. Auscultation of the lungs often shows no signs, and rales may be heard in patients with concurrent bacterial or fungal infections. The disease progresses rapidly and can deteriorate and lead to death quickly.

　　2. Chronic progressive type
　　The disease occurs 3 to 4 months after transplantation, with symptoms similar to those of the progressive type, but with slow progression, mild symptoms, and a low mortality rate. Chest X-ray shows diffuse interstitial pneumonia and fibrosis. The pathological features of the disease include alveolar interstitial edema, varying degrees of fibrosis, lymphocytic infiltration, and epithelial cell hyperplasia.
　

　　Since CMV pneumonia is common in patients with bone marrow and organ transplantation, it is necessary to do good donor screening work before transplantation, and try to choose donors with negative CMV antibodies. For antibody-positive patients, preventive acyclovir treatment can be used one week before surgery and one month after surgery, and high-titer CMV immune globulin can be administered intravenously one day before transplantation and two weeks after surgery to enhance passive immunity. After that, a dose every 3 weeks until 100 days after surgery to prevent the occurrence of CMV pneumonia.

　　The examination of CMV pneumonia includes blood examination, chest X-ray examination, and etiological examination. The specific examination is as follows:

　　1. Blood examination
　　Blood routine examination shows a decrease in peripheral blood leukocytes. The determination of serum CMV antibodies, when the titer of double serum antibodies is 4 times or more, is helpful for diagnosis.

　　2. Chest X-ray examination
　　The main manifestations are diffuse interstitial or alveolar infiltration in both lungs, a few can present as nodular shadows, and occasionally pleural effusion may occur. Pulmonary consolidation suggests concurrent bacterial or fungal infection.

　　3. Etiological Examination
　　The etiological examination of CMV includes the detection of CMV inclusion bodies in cells and viral particles, immunological methods, and molecular biological methods.

　　Patients with CMV pneumonia have low immunity, so they should pay attention to eating more protein and vitamin-rich foods appropriately. They should avoid eating cold, spicy and刺激性 foods, avoid overeating, and avoid smoking and drinking.

　　There is currently no effective drug for CMV pneumonia, which is mainly treated with acyclovir. It has the selective inhibitory effect on the DNA polymerase of herpesvirus. The drug can suppress white blood cells at high doses, aggravating the condition, and it is recommended to be 10mg/(kg·d), with a course of 4-6 weeks.