EBV infection is caused by the Epstein-Barr virus (EBV) and occurs mostly in childhood. The prognosis is good, except for immunodeficient individuals whose infection can be life-threatening. EBV has been found to be associated with certain tumors such as nasopharyngeal carcinoma, Burkitt’s lymphoma, and certain autoimmune diseases such as rheumatoid arthritis and dry syndrome. (A) Clinical manifestations 1. Asymptomatic or atypical infections are most often seen in young children. The manifestations are often mild, such as upper respiratory tract infection, tonsillitis, persistent fever with or without lymph node enlargement. 2. Acute infectious mononucleosis (IM) is a typical manifestation of primary EBV infection. Most commonly seen in older children and adolescents. It often starts with 3-5 days of prodromal manifestations: headache, malaise, malaise, fear of food, etc., followed by the following typical signs: (1) Fever, pharyngitis, lymph node enlargement triad Almost all have fever, body temperature is often ≥39.5°C for about 10 days, and then gradually decreases to normal. Pharyngitis is seen in about 80% of children and occurs within the first week of illness, and is often exudative. 90% of children have rapid enlargement of superficial lymph nodes shortly after onset of illness, which may involve the whole body, most notably the neck. (2) The spleen is enlarged and soft within 3 weeks after the onset of the disease in about 50% to 70% of cases. Rupture of the spleen is rare, but is a serious complication, so heavy pressure should not be applied when examining the spleen. (3) Liver enlargement and liver function abnormalities At the time of IM, about 40% or more of the cases showed temporary increase in liver enzymes, mostly in the range of 45 to 300 U/L, with a few reaching 500 U/L or more. Hepatomegaly is seen in 30% to 50% of children with the disease, and is more common in children under 4 years of age. About 2% to 15% are accompanied by jaundice. Liver function can be fully recovered within 2 weeks to 2 months. It usually does not cause chronic liver disease. (4) Other manifestations Rash may appear in young children, and abdominal pain may be seen in older children or adolescents. In addition, hematologic (anemia, thrombocytopenia, granulocytopenia), pulmonary (pneumonia), neurologic (encephalitis, meningoencephalitis, Guillain-Barre syndrome, peripheral facial palsy), cardiovascular (myocarditis, pericarditis) and renal (glomerulonephritis) complications are rare. (Typical blood picture Appears within 1 to 4 weeks after the disease. The main manifestations are lymphocytosis ≥ 50% and heterogeneous lymphocytosis ≥ 10%, and a white blood cell count of 10-20×109/L. If there are no complications, the course of the disease is usually 2-4 weeks, and occasionally it can be extended to several months. 3. EBV infection in children with immunodeficiency mainly refers to children with X-linked lymphoid tissue proliferation syndrome (XLP) and acquired immunodeficiency. Lethal mononucleosis, secondary low or no immunoglobulinemia, malignant polyclonal-derived lymphoma, aplastic anemia, and chronic lymphocytic interstitial pneumonia often occur. The morbidity and mortality rate is as high as 60%. (B) Pathogenic diagnosis 1. Serological examination: Positive anti-VCA IgG indicates that one has been infected or is being infected with EBV. Since its peak is in the acute phase, it is of little value to observe double sera to diagnose acute primary infection. Anti-VCA IgM appears early in the disease and disappears in about 2-3 months and is an indicator of acute primary infection. anti-VCA IgM levels in children under 4 years of age are low and disappear quickly (often within 3-4 weeks after the disease). In chronic or recurrent infections, anti-VCA IgG is high titer; anti-EA is often increased; anti-EBNA is positive (occasionally undetectable); and anti-VCA IgM is usually negative. 2. Viral marker detection: EBV DNA detection by nucleic acid hybridization and PCR in saliva or oropharyngeal washings in exfoliated epithelium, lymphatic tissue and tumor tissue is the most specific detection method. Immunolabeling techniques can also be used to detect viral antigens in the sample, such as EBNA, latent membrane antigen (one of the components of LYDMA). 3. Virus isolation: Virus isolation and identification is performed using the property that EBV infection causes unlimited proliferation of cultured B cells (human umbilical cord blood or peripheral lymphocytes). It takes 6 to 8 weeks. (C) Heterophilic antibodies The presence of heterophilic antibodies, i.e. IgM antibodies, in the patient’s serum can assist in the diagnosis. Treatment】 1.Supportive symptomatic treatment Bed rest is needed in the acute phase, and corresponding treatment such as antipyretic, analgesic and hepatoprotective is given. Short-term corticosteroids can be used cautiously in patients with severe symptoms of transmission. If secondary streptococcal infection is confirmed by pharyngeal swab culture or antigen testing, additional sensitive antibiotics are required. Those with splenomegaly should avoid significant physical activity or exercise during the recovery period to prevent splenic rupture; emergency surgical management or non-surgical treatment should be given in case of splenic rupture. Tracheal intubation or organotomy should be performed when complete airway obstruction is caused by deep upper respiratory tract inflammation. 2, antiviral treatment There is a lack of antiviral drugs that have significant efficacy against EBV infection, and nucleoside analogues such as ganciclovir have inhibitory effects on EBV, but there is a lack of suitable clinical studies to evaluate. Preliminary studies have shown some efficacy in severe EBV-induced lymphoproliferative disease using anti-B-cell monoclonal antibodies and irradiated transplanted donor leukocytes, while reducing the dosage of immunosuppressive agents.