Chen Ming, 13, has been having recurrent fever for the past 1 week, with a body temperature often exceeding 39°C. He feels weak and has a sore throat, and has taken a lot of cold medicine and antibiotics but has not recovered. In the past few days, Chen Ming also found a lump under his left ear, which seems to be getting bigger and bigger, accompanied by a vague pain. Chen Ming’s mother was very anxious. She thought her child might have leukemia or lymphoma.
The doctor performed a thorough physical examination and found that Chen Ming’s pharynx was obviously congested, and grayish-white pus moss could be seen on his tonsils bilaterally, multiple enlarged lymph nodes were palpable on the left side of his neck, and his liver and spleen were slightly enlarged. The results showed that the white blood cell count and lymphocyte ratio were slightly higher, the hemoglobin and platelets were normal, and the results of the blood smear classification showed 22% heterogeneous lymphocytes. The biochemical examination indicated elevated transaminases and a positive IgM antibody to EBV.
The doctor told Chen Ming’s mother with certainty that her child had “transmonocytosis”, or infectious mononucleosis, which is a benign disease. The mother of Chen Ming finally put her mind at ease, but what exactly is the matter with the “passwords”?
The most common pathogen is the EB virus, and the rare cytomegalovirus, toxoplasmosis, adenovirus, hepatitis virus and other infections may also show similar symptoms. The disease is most commonly seen in preschool and school-age children and is transmitted primarily by droplets and saliva through the respiratory tract, but can also be transmitted through close contact.
Because most children under 6 years of age have no or mild clinical symptoms after infection with EBV, they can acquire lasting immunity after infection. Only a small percentage of children with the infection present with fever and enlarged lymph nodes. Therefore, although infectious, mononucleosis does not fall into the category of infectious diseases that require strict management according to China’s Infectious Disease Control Law.
How is infectious mononucleosis diagnosed?
Children with infectious mononucleosis often have clinical manifestations such as fever, pharyngitis and tonsillitis, enlarged lymph nodes in the neck (>25px), enlarged liver, enlarged spleen, etc. In routine blood tests, the total white blood cell count is often mildly elevated, with the proportion of lymphocytes greater than 50% or the total number of lymphocytes exceeding 5.0×109/L, and heterogeneous lymphocytes ≥10% are seen in blood smears. The most critical and commonly used clinical test is antibody monitoring for EBV. Positive anti-EBV-VCA-IgM antibodies suggest the presence of recent EBV infection. The diagnosis can also be aided by the detection of EBV DNA in blood, saliva, oropharyngeal epithelial cells, urine or tissue by PCR.
How is the differentiation between infectious mononucleosis and malignancy made?
Because children with infectious mononucleosis have fever, enlarged lymph nodes, liver and spleen, and a high number of heterogeneous lymphocytes in the peripheral blood, they are often mistaken for malignant diseases such as lymphoma or leukemia. However, children with infectious mononucleosis often do not have anemia or thrombocytopenia, and therefore rarely present with pallor, malaise, or bleeding in the skin and mucous membranes; in addition, the symptoms of fever and lymph node enlargement are self-limiting and will improve on their own after 2-3 weeks of illness. These are different from leukemia and lymphoma. In some cases where differentiation is difficult, bone marrow aspiration may be considered to assist in the diagnosis if necessary.
How is infectious mononucleosis treated?
Because conventional antiviral drugs are currently ineffective against EBV infection, and because of the self-limiting nature of the disease, children with milder symptoms usually do not require special treatment and can generally be given only symptomatic treatment, including antipyretic and hepatocyte-protective therapy. In addition, care should be taken to rest and avoid serious comorbidities such as rupture of the obviously enlarged spleen. Antibiotics may be used in the event of secondary bacterial infection of the pharynx and tonsils.
Can infectious mononucleosis turn into other diseases?
The prognosis for infectious mononucleosis is mostly good, and the course of the disease is usually 2 to 4 weeks. In some children, symptoms such as low-grade fever, swollen lymph nodes, and malaise may last for weeks or months, and in rare cases, the disease may extend for several years. For children with persistent EBV and clinical manifestations such as fever and swollen lymph nodes, the medical term is “chronic active EBV infection”. In a very small number of children, EBV infection is associated with persistent fever with marked increase in ferritin, significant decrease in fibrinogen, and increase in triglycerides, which is called “hemophagocytic syndrome”. It may cause death due to hemorrhage, organ damage, and central nervous system involvement, and requires additional supportive therapy and chemotherapy. In addition, very few EBV infections have been associated with the development of lymphoma. Therefore, children with long-lasting and severe infectious mononucleosis should be vigilant for the possibility of these diseases.