Cytomegalovirus infection

　　1, Sources of infection include patients and asymptomatic carriers who can excrete the virus for a long time or intermittently from saliva, tears, cervical secretions, urine, semen, feces, blood, or breast milk, making them sources of infection.

　　2, The common feature of CMV infection is that it is widely prevalent in humans and distributed worldwide. CMV has different strains, and antibodies cannot protect children from infection by other strains. The occurrence of CMV infection is related to age, region, and economic status, and the infection rate is higher in crowded living conditions and poor hygiene. This virus can be found in the saliva of 10% to 25% of healthy people, in the cervix of 10% of healthy women, in the urine of 2% to 5% of pregnant women, in the urine of 1% of newborns, and in the blood of 1% to 2% of young people. Up to 60% to 90% of adults have antibodies against CMV. The Capital Institute of Pediatrics (1987) used ELISA to determine that the positive rate of CMV-IgG antibody in the normal population over 30 years old in Beijing was 90%.

　　3. When the mother has primary CMV infection, the virus is widely present in various organs of the host and can be transmitted through the placenta to infect the fetus, especially in the first four months of pregnancy, which is more likely to cause harm to the fetus. Early infection of the fetus can cause immune tolerance of host cells, allowing the virus to slowly multiply within cells, causing organ damage. In severe cases, it can lead to abortion or stillbirth, while in mild cases, it can cause low birth weight or malformation. Congenital infection in infants often carries the risk of significant sequelae, especially affecting the central nervous system.

　　4. Recurrent infection during pregnancy does not necessarily lead to congenital infection in the fetus, at this time the viral load in the mother is less than that in the primary infection. Infants infected through the cervix have a high risk of infection in the first few months after birth. Acquired infections are mostly asymptomatic, but they can continuously or intermittently excrete the virus, and the symptoms are also relatively mild when they occur.

　　Children with congenital cytomegalic inclusion disease have a high mortality rate and many sequelae. Especially those with jaundice, thrombocytopenia, intracranial calcification, and enlargement of the liver and spleen have poor prognosis. Most die of liver cirrhosis, and survivors often have permanent neurological sequelae, such as microcephaly, mental retardation, developmental and motor disorders, deafness, etc. However, some infants infected intrauterinely can survive without significant sequelae. Acquired cytomegalic inclusion disease is often self-limiting and has a good prognosis. However, individuals with severe chronic consumptive diseases, organ transplants, AIDS children, or those who have been taking immunosuppressive agents for a long time have poor prognosis.

　　When the following conditions occur during childhood, consider the possibility of acquired cytomegalic inclusion disease:

　　1. Chronic liver disease or persistent interstitial pneumonia that cannot be explained by other causes.

　　2. Clinically similar to infectious mononucleosis, but the heterophilic agglutination test against EB virus capsid antigen is negative, and it often occurs in individuals who receive a large amount of fresh blood after surgery (especially open heart surgery).

　　3. Children with chronic consumptive diseases receiving immunosuppressive therapy (such as leukemia, malignant tumors) and recipients of organ transplants often suffer from severe pneumonia, which is often caused by CMV infection.

　　Cytomegalovirus poses a great threat to humans, so we should actively prevent its occurrence:

　　1. Engage in conscious physical fitness training. Improve the body's immune function and disease resistance, especially for women of childbearing age, to reduce the serious harm of cytomegalovirus to the fetus.

　　2. Patients who are pregnant or have chronic consumptive diseases, low immunity, and other conditions should be protected to keep them away from the source of infection.

　　3. Pay attention to environmental and dietary hygiene.

　　4. Women with positive CMV in breast milk should not breastfeed.

　　5. Immune prevention and treatment are still under research and exploration.

　　One, blood count and liver function

　　Anemia and thrombocytopenia may occur, and the clinical symptoms are similar to those of infectious mononucleosis in children. Abnormal lymphocytes can be seen in peripheral blood smears. The serum bilirubin level in jaundice patients is increased, and there is an increase in serum transaminases. Viral and serological examinations can be used to make a definite diagnosis.

　　Two, etiology

　　1. Detection of CMV: Urine, bronchoalveolar lavage fluid, saliva, liver tissue, or pharyngeal secretions can be inoculated into human embryonic lung fibroblasts to culture CMV. Swollen round cell lesions usually appear within a week, but it takes 4-6 weeks to affect the entire monolayer of cells. Since the conditions required for virus isolation are high, and CMV grows slowly, it is not suitable for promotion. The fresh morning urine sediment is stained and the giant cells containing inclusions are searched, which is a commonly used method in clinical practice. However, the detection rate of these cells is low, and multiple careful inspections are needed to concentrate urine for examination under an electron microscope. CMV can also be detected using in situ hybridization, monoclonal antibody indirect immunofluorescence, ELISA sandwich method, and flow cytometer to detect CMV antigens in clinical specimens.

　　2. Detection of CMV-DNA: CMV-DNA in pregnant women's urine can be detected by DNA-DNA hybridization; CMV-DNA in children's urine can be measured by polymerase chain reaction; and CMV-DNA can be detected by probes labeled with digoxigenin.

　　Three, serology

　　The complement fixation test is commonly used to determine IgG antibodies. The titer of this antibody in the convalescent serum needs to be increased ≥4 times compared to the acute phase to be of diagnostic significance, so it cannot be used for early diagnosis. In recent years, fluorescence antibody indirect staining, indirect ELISA, radioimmunoautography, capture ELISA, and indirect enzyme-linked immunosorbent assay have been used to detect CMV-IgM antibodies in the serum of children, which is helpful for early diagnosis.

　　Diet should avoid spicy and刺激性 foods, eat more fresh vegetables and fruits, and foods high in protein. The diet of patients should be light and easy to digest, eat more vegetables and fruits, reasonably match the diet, and pay attention to sufficient nutrition. In addition, patients should also pay attention to avoid spicy, greasy, and cold foods.

　　Precautions before the treatment of cytomegalovirus infection

　　1. The goal of prevention is to prevent as many high-risk seronegative individuals from being infected with CMV as possible, and to reduce the reactivation of CMV in seropositive individuals to the lowest level.

　　2. There is currently no effective method to prevent the activation of CMV during pregnancy. Washing hands thoroughly is the best way to reduce CMV infection in pregnant women. The application of high-titer immunoglobulins is under study. Antiviral drugs have no preventive effect.

　　3. Kindergartens and nurseries and other institutions are important places for the spread of the disease, causing infections among children and among staff and parents with serum antibody-negative antibodies. Staff in baby rooms with serum antibody-negative antibodies are also easily infected by contacting the secretions (diapers, urine, saliva, etc.) of infected infants. The most effective preventive measure is good hygiene habits, such as hand washing, etc.

　　4. Preventive measures against sexual transmission are also important.

　　5. This virus can be transmitted through blood transfusion, so it is advisable to avoid unnecessary blood transfusions. Serum CMV antibody-negative blood products (at least IgM negative) or not to transfuse blood cells should be used for premature infants, newborns, immunodeficient individuals, organ transplant recipients, and pregnant women as much as possible. The transplanted organs can be a source of CMV infection, and serum antibody-negative organs or tissues should be used as much as possible.

　　Second, Western medical treatment methods for cytomegalovirus infection

　　1. Various antiviral agents such as GCV, immunoglobulins against cytomegalovirus, interferon, and transfer factors can be used. However, these drugs cannot solve the fundamental problem, and viruses often relapse after drug discontinuation.

　　2. Recently, American scholars have developed two live vaccines, which have shown good effects in preliminary trials. One is developed from the AD169 strain; the other is made from the TOWn strain, which has been shown to have anti-cytomegalovirus efficacy after intravenous administration, leading to increased CMV antibodies and enhanced immune function.

　　3. Ganciclovir (ganciclovir DHPG) has the effect of preventing the spread of CMV. When used in combination with high-titer anti-CMV immunoglobulins, it can reduce the mortality rate of CMV pneumonia complications in bone marrow transplantation. If CMV infection that is resistant to ganciclovir can be chosen, phosphonoacetic acid can be used, although it can persistently reduce the spread of CMV, but its effect is worse than the former.

　　4. Acyclovir (acyclovir) and acyclovir (acyclovir) are effective in treating other herpesvirus diseases, but they have no effect on CMV infection. However, the derivative of acyclovir, DHPG (9-guanosine), is 25-50 times stronger than acyclovir in vitro, but it also has serious side effects, with neutropenia being the most common side effect. The efficacy and safety need further study.