Cytomegalovirus infection

Introduction to cytomegalovirus infection Giant cell inclusion body infection is a congenital or acquired infection caused by cytomegalovirus (CMV). There are two types, most of which become invisible or chronic infection of salivary glands and persist for a long time. The other is systemic. The disease, called cytomegalic inclusion disease, is relatively rare, mainly invading small babies. It is characterized by the discovery of large cells containing intranuclear and intracytoplasmic inclusions in many organs and tissues, accompanied by systemic symptoms. One of the important causes of fetal malformation caused by internal virus infection. basic knowledge The proportion of sickness: 0.0052% Susceptible people: infants and young children Mode of infection: 1. Blood transmission 2. Body fluid transmission 3. Mother-to-child transmission Complications: jaundice, mental retardation, dyskinesia, deafness

Cause of cytomegalovirus infection

way for spreading

(1) Congenital infection: After the pregnant woman is infected with CMV, the virus is transmitted to the fetus through the placenta. The mother can produce antibodies after infection. After birth, the fetus will have less chance of infection or mild symptoms, even asymptomatic, but not Completely prevent the occurrence of vertical propagation.

(2) acquired infections: including perinatal neonatal birth or breast milk infection, 2 close contact with infection, mainly through droplets or oral infection, often spread to other children through toys, 3 transfusion, organ transplant infection .

Susceptibility to the crowd

The younger the age, the higher the susceptibility and the heavier the symptoms. The older children are mostly non-dominant infections. CMV is an intracellular infection. Although there are antibodies in the blood, it can not avoid the persistence of this virus in the cells, so the initial infection After that, CMV is difficult to be completely removed by the host.

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CMV infection is prevalent in humans, infection is 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 is crowded. The infection rate is poor in poor sanitation, in 10% to 25% of healthy people's saliva, 10% of healthy women's cervix, 2% to 5% of pregnant women's urine, 1% of neonatal urine, 1% to 2% The virus can be found in the blood of young people. 60% to 90% of adults can contain CMV antibodies in the blood. The Capital Institute of Pediatrics (1987) used ELISA to determine the positive rate of CMV-IgG antibody in the normal population over 30 years old in Beijing.

When the mother is suffering from primary CMV infection, the virus is widely present in various organs of the host, and can infect the fetus with blood flow through the placenta, especially within 4 months of pregnancy, which is more likely to cause fetal damage. The cellular immune tolerance of the cells allows the virus to proliferate slowly in the cells, causing organ damage. If the consequences are severe, it may cause miscarriage, stillbirth, and light birth weight or deformity. Infants' congenital infections often have obvious The danger of leaving damage, especially the central nervous system.

Recurrent infection during pregnancy does not necessarily lead to congenital infection of the fetus. At this time, the amount of maternal virus is less than that of the original. When the baby is infected with the cervix, there is a high risk of infection in the first few months of life. Most acquired acquired infections are asymptomatic. However, the virus is discharged continuously or intermittently, and the symptoms are mild at the time of onset.

Cytomegalovirus infection prevention

prevention

Cytomegalovirus is very harmful to humans, so we should actively prevent it from happening.

(1) Carry out conscious physical exercise, improve the body's immune function and disease resistance, especially women of childbearing age, to reduce the serious harm of cytomegalovirus to the fetus.

(2) For pregnant women or patients with chronic wasting diseases, patients with low immunity should pay attention to protection and keep them away from the source of infection.

(3) Pay attention to environmental hygiene and food hygiene.

(4) Those who are positive for cytomegalovirus in milk should not breastfeed.

(5) Immunological control is still under research and exploration.

After CMV causes intracellular infection, the inactivated vaccine has no obvious preventive effect. When there is a primary infection of CMV in early pregnancy and/or CMV antigen in amniotic fluid cells, the pregnancy should be stopped, and the live attenuated vaccine can produce antibodies to the recipient. And produce cellular immunity to CMV to reduce the occurrence of symptomatic CMV infection. CMV high-valent immunoglobulin has a certain protective effect on symptomatic CMV infection in serum CMV-negative bone marrow transplant recipients, but it cannot prevent re-infection. Wash hands carefully after contact with children's urine or saliva to prevent acquired CMV infection.

To prevent CMV infection caused by fresh blood, the following methods can be used: 1 use frozen blood or washed blood; 2 store more than 48 hours before blood input; 3 use radiation-irradiated blood; 4 use blood filter to remove blood Giant cells.

Cytomegalovirus infection complications Complications, jaundice, mental retardation, dyskinesia, deafness

Children with congenital giant cell inclusion disease have high mortality and sequelae, especially jaundice, thrombocytopenia, poor prognosis of intracranial calcification and hepatosplenomegaly, and more death from cirrhosis. Survivors often leave permanent Nervous system sequelae, such as microcephaly, mental retardation, developmental and dyskinesia, deafness, etc., but some intrauterine infections can survive without obvious sequelae, acquired acquired giant cell inclusion disease is self-limiting, prognosis Good, but the original serious chronic wasting disease, organ transplantation, AIDS children or long-term use of immunosuppressants have a poor prognosis.

Symptoms of cytomegalovirus infection common symptoms growth slow jaundice peripheral neuritis lymph node enlargement convulsion deafness toxemia optic atrophy biliary obstruction immunity reduced

The clinical manifestations of this disease vary in severity. Systemic giant cell inclusion disease mainly occurs in neonates and infants. In this case, jaundice, hepatosplenomegaly, skin defects, microcephaly, intracranial calcification, etc. should be seen. Note that with toxoplasmosis, sepsis, congenital biliary obstruction, infantile hepatitis, systemic herpes simplex, congenital leukemia, congenital rubella syndrome, etc., mental retardation, dyskinesia, cerebral palsy and other symptoms are generally in older babies be found.

The possibility of acquiring giant cell inclusion disease should be considered in the following cases in childhood: 1 chronic liver disease or persistent interstitial pneumonia that cannot be explained by other causes; 2 clinically similar infectious mononucleosis, but resistant The heterophilic agglutination test of EB virus capsid antigen is negative, often occurs in a large number of fresh blood after surgery (especially happy surgery); 3 children with chronic wasting disease (such as leukemia, malignant tumor) receiving immunosuppressive agents, accept Recipients of organ transplants, such as the occurrence of more severe pneumonia, are often caused by CMV infection.

In the case of the above, virological and serological tests are required to confirm the diagnosis.

Most CMV infections are not dominant, and the performance after infection is diverse. Symptoms are divided into two types:

1, congenital infection: about 10% of children with obvious symptoms after birth, manifested as hepatosplenomegaly, persistent jaundice, skin defects, microcephaly, chorioretinitis, mental retardation and movement disorders, etc. A single performance can exist alone, and can be accompanied by slow growth, irritability, and sometimes fever, body temperature from micro-heat to 40 ° C, but only a small number of children have clinical symptoms at birth, so most can not determine the diagnosis, such as Symptoms that appear only after a few months to several years can also manifest as hearing loss, mild neurological symptoms and developmental disorders, which may affect learning. Children with congenital giant cell inclusion disease may have various congenital malformations. state, bilateral convulsions, epileptiform convulsions, optic atrophy, deafness (about 10% of children with deafness), and increased sensitivity to bacterial infection, some children with asymptomatic congenital CMV infection, although physical development Normal, there may still be congenital malformations and hearing damage, but the incidence and severity are lower than those with symptoms.

2, acquired infection: The disease is a self-limiting disease, the clinical manifestations are generally lighter, although most infants are subclinical infections, but the incidence of symptoms is still higher than adults, manifested as liver, spleen and lymph nodes, Hepatitis can also occur in rash, bronchitis or pneumonia. Children with congenital infections are rarely invaded by the nervous system. Childhood infections are often obtained through the respiratory tract, often not dominant, but become long-term carriers. Occasionally, prolonged hepatitis or interstitial pneumonia may occur in children with multiple blood transfusions. The disease may resemble infectious mononucleosis, but the heterophilic agglutination of EBV capsid antigen Reaction and IgM antibodies are always negative, can also cause hemolytic anemia or infectious peripheral neuritis, activation of indominant CMV infection often occurs in a variety of factors that reduce the body's immunity, allowing potential viral infections to be activated Onset, these factors include pregnancy, organ transplantation, application of immunosuppressants or antimetabolites, surgery, giant blood disease, tumors, etc., may occur pneumonia, hepatitis retinitis, Interstitial pneumonia is the most serious consequence of CMV infection in bone marrow transplant recipients. The incidence rate is 40%, and the mortality rate is 90%. Children with AIDS have a high CMV infection rate, which is characterized by prolonged viremia. Progressive development is often the most common cause of death.

Inspection of cytomegalovirus infection

1, blood and liver function

There may be anemia and thrombocytopenia, clinically similar to children with infectious mononucleosis, more abnormal lymphocytes can be seen on peripheral blood smears, serum bilirubin increased in children with jaundice, accompanied by elevated serum transaminase, Diagnosis can be confirmed by virology and serological examination.

2. Etiology

(1) Detection of CMV: Inoculation into human embryonic lung fibroblasts with urine, bronchoalveolar lavage, saliva, liver biopsy or pharyngeal secretions, CMV can be cultured, usually with a swollen round cell lesion within 1 week, but It takes 4-6 weeks to spread the whole single layer of cells. Due to the high conditions required for virus isolation and the slow growth of CMV, it is not suitable for promotion. It is necessary to dye fresh morning urine sediment smears and find giant cells with inclusion bodies. One method, but the detection rate of this kind of cells is low, and it is necessary to check carefully. The concentrated urine can be seen under the electron microscope. CMV can also be used. In situ hybridization, monoclonal antibody indirect immunofluorescence, ELISA sandwich Method and flow cytometry to detect CMV antigen in clinical specimens.

(2) Detection of CMV-DNA: CMV-DNA in pregnant women can be examined by DNA-DNA hybridization; CMV-DNA in urine of children is detected by polymerase chain reaction; CMVDNA is detected by probe labeled with digoxigenin .

3. Serology

IgG antibody is commonly used in the complement-binding assay. The titer of this antibody in the recovery period is more than 4 times higher than the acute increase in diagnostic value, so it can not be used for early diagnosis. In recent years, fluorescent antibody indirect staining, indirect ELISA, radioimmunoassay Self-development, capture ELISA, indirect enzyme-based inhibition, etc., detection of CMV-IgM antibodies in the serum of children, is helpful for early diagnosis.

Diagnosis and identification of cytomegalovirus infection

diagnosis

The clinical manifestations of this disease vary in severity. Systemic giant cell inclusion disease mainly occurs in neonates and infants. In this case, hemorrhagic splenomegaly is seen in the skin of the spleen and hepatic splenomegaly.

Differential diagnosis

Should be noted with toxoplasmosis sepsis, congenital biliary obstruction, infantile hepatitis, systemic herpes simplex, congenital leukemia, congenital rubella syndrome.

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