Pediatric cytomegalovirus pneumonia
Introduction
Introduction to Pediatric Cytomegalovirus Pneumonia Giant cell inclusion body virus infection is not obvious in most cases of congenital or acquired cases. Symptoms are called cytomegalic inclusion disease, and cytomegalovirus pneumonia is an integral part of this disease. CMV is mostly a recessive infection, which can also cause giant cell inclusion disease, which can occur before, at birth or after birth. Pre-natal (intra-fetal infection) is a congenital infection; if the patient is born or born after the birth of the infection, the former is mainly caused by central nervous system damage, the latter mostly have serious lesions of the lung tissue. basic knowledge The proportion of children: the incidence rate of children is about 0.001% -0.002%, more frequent in autumn and winter Susceptible people: children Mode of infection: contagious Complications: Adenovirus infection
Cause
Pediatric cytomegalovirus pneumonia
Mainly all the organs of the whole body are widely involved, and the pathological changes of the lungs are mild, mostly congenital infections, the pleura, larynx, and trachea are normal, the chest lymph nodes are not swollen, only a little purple-red infarct-like lesions, the pressure-cut surface has blood color Fluid, microscopic bronchial changes, no ulcers and necrosis, bronchial wall vascular congestion, alveolar congestion and edema, alveolar septum light thickening, alveolitis lesions filled with phagocytic cells, alveolar and bronchial cavity with giant cells, Giant cells are found in the bronchioles and mucous glands and around the alveoli.
Lung tissue damage is the main, or the only pathological change, the lung tissue is congested, the cut surface is rugged, the appearance is grayish yellow, and the bloody pulp is exuded. The bronchial cavity is filled with inflammatory multinucleated cells and mononuclear cell debris. The bronchial wall is thickened and congested, the interstitial cells of the lungs are infiltrated, the mucous glands around the bronchioles are infiltrated by mononuclear cells, the interstitial space is thickened, the tissue cells proliferate, and the giant cell inclusions are found at the edge of the alveolar compartment. Typical CMV Infected cells are swollen, and there are huge eosinophilic inclusions (or occasionally basophilic inclusions) in the nucleus. There is an unstained halo separated from the nuclear membrane, and a large expanded nucleus can be seen. The cytoplasm can also be seen. To be inclusive.
The lung tissue is a miliary necrosis, which is a small nodular nodule. It is solid and elastic, with obvious boundaries. It can also be scattered or fused. The microscopic lesions are scattered and necrotizing lesions at the beginning of the lesion. The alveoli are filled with cellulose, red blood cells and mature grains. Cells, tissue cells and cell debris. These lesions have swollen alveolar cells containing inclusion bodies. There are often transparent membrane changes in the alveoli. If CMV infection is a systemic disease, in addition to lung lesions, there are liver, brain, kidney, digestive tract, Salivary glands, heart, adrenal glands, gonads, skin, etc. can be affected, mainly to interstitial inflammation and focal necrosis, infected cells are large, contain inclusion bodies, infants and adults perform differently in disease, not only because of their sensitivity Different, and, in connection with adult exposure to pathogens, in infants, the inclusions mainly occur in epithelial cells. Adults found that in the mesenchymal component, patients receiving kidney transplantation isolated CMV from the lungs, indicating that the lungs have Infection, some people believe that the presence of high levels of serum antibodies and immune complexes reveals that allergic reactions may be involved in the pathogenesis, and cellular immunity is also inhibited. May be related to this.
Prevention
Pediatric cytomegalovirus pneumonia prevention
The key to the prevention of CMV pneumonia is the prevention of CMV infection. Some people who have negative CMV antibody or susceptible to organ transplantation and immunosuppressive drugs use high-valent immune serum as passive immunity after exposure to CMV. The disease has not achieved the expected effect, and it has no therapeutic effect on the infected person. Many attempts have been made to prevent CMV infection with vaccine, which proves that it is possible to prepare a drug that induces antibodies without serious reaction and detoxification. Human CMV vaccine, Neff et al reported that live vaccine was made with ADL68 strain, for small-scale inspection, all antibodies were positive, the clinical response was light, and no virus was found in throat swab, urine and white blood cells. Therefore, CMV will be pregnant. It is meaningful to vaccinate normal women with negative antibody and those who are going to perform organ transplantation. Because CMV can cause intrauterine infection, it causes congenital malformation, and it is also a complication after organ transplantation and massive transfusion. It is potentially carcinogenic due to herpesvirus. Although there is currently insufficient epidemiological evidence that CMV is linked to human cancer, it also affects this work extensively. Suspected congenital infection, therapeutic abortion can be controlled, with CMV infection, the virus can be urine, saliva, cervical secretions present in the milk and, by contact, it is recommended that the patient should be isolated.
Complication
Pediatric cytomegalovirus pneumonia complications Complications Adenovirus infection
Patients with long-term immunosuppressive drug therapy and organ transplantation are susceptible to bacterial infections when CMV infection and pneumonia occur, as well as adenovirus infection, and some patients may have diffuse interstitial pulmonary fibrosis (Hamman-Rich syndrome). ).
Symptom
Pediatric cytomegalovirus pneumonia symptoms common symptoms three concave sign liver splenomegaly respiratory distress syndrome hair jaundice dyspnea
Whether it is congenital or acquired giant cell inclusion disease, pneumonia is often masked by other serious systemic symptoms. Neonatal giant cell pneumonia can be characterized by persistent respiratory distress, but often hepatosplenomegaly, jaundice, purpura and central Nervous system damage, several months after birth, pneumonia can also be combined with liver, spleen enlargement, sometimes complicated by Pneumocystis carinii pneumonia, lung symptoms are similar to other non-bacterial pneumonia, cough, difficulty breathing, cyanosis And three concave signs, auscultation, no abnormalities, and lung X-ray changes are not parallel, X-ray chest radiographs can be seen in a wide range of cord-like texture thickening and lobular inflammatory infiltrates, showing a dot-like shadow, the child has a virus In the case of bloody, there is a manifestation of chronic hepatitis such as hepatomegaly and liver dysfunction, and monocytosis caused by cytomegalovirus is difficult to distinguish from infectious mononucleosis caused by EBV.
Examine
Examination of pediatric cytomegalovirus pneumonia
Because CMV non-dominant infections are widespread, caution should be exercised in interpreting positive laboratory results. Virus isolation, serology, and cytopathology must be combined to confirm the diagnosis. Traditional laboratory methods include viral isolation and complement fixation. Three kinds of tests and neutralization tests were taken. The urine, pharyngeal lotion, sputum, gastric juice, cerebrospinal fluid or organ biopsy and autopsy tissue were inoculated into sensitive cells. After 24 hours of culture, inclusion bodies were observed by special staining, and cytopathic lesions appeared. It takes several days to two weeks, or even up to 6 weeks, to detect the acute and recovery sera of the children by complement fixation test or neutralization test. The antibody titer of both drugs is more than 4 times higher, which is positive. As a result, when the titer of the complement fixation test is higher than 1:8, it can be considered that the infection has been affected by CMV (active infection). These traditional methods are accurate and reliable, require a long time, and are retrospectively diagnosed. Some of the more sensitive methods, the most important ones are immunofluorescence, enzyme-linked immunosorbent assay and radioimmunoassay, etc. Off method.
1. Early antigen (EA) assay: A few hours after CMV infection, an early antigen has appeared before viral DNA replication, its nature is not clear, but can be detected as an indicator of early CMV infection, using immunofluorescence Enzyme-linked immunosorbent assay can detect the level of EA in serum. It is suggested that the appearance of EA not only indicates early CMV infection, but also may indicate the activation of previous latent infection.
2. Specific IgM assay: The first increase in serum antibody after CMV infection is specific IgM. The specific antibody reaction can be detected at an early stage by sensitive radioimmunoassay or enzyme-linked immunosorbent assay, thus making early rapid diagnosis. Since IgM cannot pass through the placenta, CMV-specific IgM is measured in neonates, indicating that it is an active infection.
3. Convection immunoelectrophoresis coarse screening test: the known antigen (CMV) is placed in the cathode plate, the serum of the patient to be tested is placed on the anode plate, and the specific IgM in the serum can be measured by using a convection immunoelectrophoresis apparatus. This method is several hours. The results are simple and simple, but the sensitivity is not very high. Only positive serum containing 1:128 or more of complement-binding antibody can be detected and used as a coarse screening test.
4. Urine sediment cell detection: Take a drop of urine sediment, fix it and stain it, then observe it under ordinary light microscope. It can be seen that the special shape of giant cells is enlarged, the nucleus is expanded, and there is a "halo" around it, similar to the eagle. The inclusion bodies of eosinophilic red stains can be seen in the eyes, cytoplasm and nucleus. Such cells are unique to CMV infection. This method should be checked with multiple patience to increase the positive rate. Those who do not find giant cells cannot exclude CMV. infection. 5. Other peripheral blood mononuclear cells, sometimes with thrombocytopenia, blood biochemical tests for jaundice or metabolic acidosis and hypoxemia.
5. B-ultrasound: often accompanied by spleen, liver.
6. X-ray inspection:
(1) Chest X-ray: the appearance of lung signs, earlier than the appearance of lung signs, mainly the performance of interstitial pneumonia, small flake shadows on one or both lung fields, network or nodules may appear Such a shadow, this phenomenon occurs mostly in the tip of the lung, and sometimes there is obvious emphysema.
(2) X-ray examination of the skull: sometimes ventricular calcification can be seen; those infected before birth may have microcephaly, hydrocephalus and so on.
Diagnosis
Diagnosis and diagnosis of cytomegalovirus pneumonia in children
diagnosis
The disease lacks unique clinical manifestations and often requires virological and serological diagnostic methods.
1. Pathogen examination: Human embryonic lung fibroblasts can be used to isolate cytomegalovirus from patient respiratory secretions and urine culture. After smear smear, giant cells with inclusion bodies can be found. Molecular biology techniques: polymerase chain The direct detection of cytomegalovirus DNA by reaction (PCR) method has the advantages of rapid, specific and sensitive compared with virus isolation. It has been applied to early rapid diagnosis, HCMVpp65 detection: HCMVpp65 is the late antigen of HCMV, and HCMVpp65 antigenemia is active. An important marker for HCMV infection is the direct detection of HCMV-encoded proteins in infected cells using monoclonal antibody technology and immunostaining. The sensitivity and specificity of this method for diagnosing active HCMV infection is 90%.
2. Serological examination: Application of immunofluorescence, indirect hemagglutination inhibition and complement fixation, etc., can be found that antibody titer is elevated, using indirect immunofluorescence assay, immunoenzymatic staining and enzyme-linked immunosorbent assay (ELISA) CMV-IgG and IgM antibodies, CMV-IgM antibody positive indicates recent infection, has diagnostic value, single blood CMV-IgG antibody positive indicates previous infection, and acute serum and recovery double serum CMV-IgG antibody titer is 4 times Or a more than 4 times increase in diagnostic significance, indicating a recent infection.
Differential diagnosis
CMV pneumonia and other viral pneumonia are only difficult to distinguish from their own clinical symptoms. If there are other symptoms of the whole body, it can be used as a reference. The diagnosis depends on the pathogen diagnosis of the laboratory. In addition, CMV pneumonia should be associated with sepsis, herpes simplex, congenital measles. It is differentiated from patients with pneumonia such as toxoplasmosis.
