Infectious mononucleosis is an acute proliferative infectious disease of the monocyte-macrophage system, mainly caused by EBV, characterized by irregular fever, pharyngitis, enlarged lymph nodes and liver and spleen, significant increase in peripheral blood lymphocytes and abnormal lymphocytes, positive heterophilic agglutination test, and post-infection body Anti-EBV antibodies appear in the body after infection. It is common in pediatrics, and children under 6 years of age often show mild or even invisible infection.
EBV is a group of herpes viruses. EBV has five antigenic components, namely viral capsid antigen (VcA), membrane antigen (MA), early antigen (EA), complement binding antigen (soluble antigen S), and nuclear antigen (EBNA). All antigens produce corresponding antibodies.
EBV is prevalent in the population and infects early in life with few symptoms. About 15% of the healthy population is virulent. More than 80% of patients have EBV in the nasopharynx, and 15-20% can carry the virus in the pharynx for a long time after recovery. Close oral and nasal contact is the main route of transmission, but it can also be transmitted by droplets and blood transfusion. The population is universally susceptible, but it is more common in children and adolescents, and most infections over 15 years of age have a typical onset. The disease can be followed by lasting immunity, and a second attack is uncommon.
I. Clinical manifestations.
The incubation period is 4 to 15 days, usually 10 days. The onset of disease varies. About half of the patients have prodromal symptoms lasting 4-5 days, such as malaise, headache, sore throat, poor appetite, nausea, loose stools, chills, sweating, shortness of breath, etc. Although the symptoms of the disease are diverse, most of them can appear more typical.
(a) Fever: The fever type is variable. The height varies, mostly between 38 to 40℃. The fever can last from several days to several weeks or even several months. May be accompanied by chills and sweating. Poisoning symptoms are mostly not serious.
(b) Lymph node enlargement: almost every case has it. Acute enlargement of lymph nodes is one of the characteristics of the disease, with cervical lymph node enlargement being the most common, followed by axillary and inguinal areas. They are 1-4 cm in diameter, moderately hard, scattered, without obvious pressure, non-purulent and asymmetric bilaterally. It takes several weeks to several months to resolve. The enlarged mesenteric lymph nodes cause abdominal pain and pressure pain. The enlarged talar lymph nodes are somewhat specific.
(iii) Pharyngitis: Although only half of the patients complain of sore throat, pharyngeal congestion is seen in most cases, and in a few patients, ulcers and pseudomembranes are formed in the pharynx and bleeding spots are visible. The gums may also be swollen or have ulcers. Edema and obstruction of the larynx and trachea are rare.
(d) Hepatosplenomegaly: about 20% of patients have hepatomegaly and hepatic tenderness, and up to 2/3 of patients have abnormal liver function. a few patients may develop jaundice, but chronicity and liver failure are rare. more than 50% of patients have mild splenomegaly, and occasionally splenic rupture may occur. The spleen should be lightly pressed during examination to prevent rupture.
(e) Skin rash: About 10% of cases have a polymorphic skin rash of light red maculopapular rash, or measles-like, scarlet fever-like, or urticaria-like rash, mostly on the trunk, which recedes within a week without desquamation.
(f) Neurological symptoms: seen in a few severe cases. More than 90% can recover.
The duration of the disease is mostly 1 to 3 weeks, and a few can be extended for several months. Occasionally, there is recurrence, and the duration of recurrence is short and mild. The disease is generally benign, self-limiting, and has a good prognosis, except for deficiencies in defense against EBV or rare serious complications, most of which can be fully recovered. The death rate is only 1 to 2%, mostly due to serious complications.
Second, the diagnostic criteria for infectious mononucleosis.
Clinical manifestations.
① fever; ② pharyngitis; ③ lymph node enlargement; ④ hepatosplenomegaly; ⑤ skin rash.
Laboratory tests.
① peripheral blood picture with increased white blood cell count and decreased platelets. The proportion of lymphocytes is increased, and the percentage of heterogeneous lymphocytes exceeds 10%; ② positive heterophilic agglutination test; ③ positive anti-EB virus antibody VCA-IgM.
Extranasal monocytic syndrome: the presence of heterogeneous lymphocytes in peripheral blood, but negative heterophilic agglutination test.
The diagnosis is confirmed by the presence of any three of “1” and any two of “2”, plus “3” above.
Complications.
(a) Respiratory system: About 30% of patients may have pharyngeal bacterial infection. 5% of patients may have interstitial pneumonia.
(b) Urinary system: some patients may develop edema, proteinuria, tubular type in urine and increased blood urea nitrogen and other changes similar to nephritis, and the lesions are mostly reversible.
（Cardiovascular system: about 6% of patients have myocarditis, and the electrocardiogram shows T-wave inversion, hypoplasia and prolonged P-R interval.
（Neurological system: Few children can have encephalitis, aseptic meningitis, and Green-Barre syndrome.
(v), digestive system: mainly increased liver enzymes, jaundice may be present, etc.
IV. Prognosis.
The disease is a self-limiting disease, if no complications prognosis is mostly good, the course of 1-2 weeks. However, it can also be repeated, and a few recover slowly, such as low fever, swollen lymph nodes, weakness, etc., which can last for weeks or even months. The mortality rate is only 1-2% due to respiratory failure caused by complications of central and peripheral nerve paralysis; a few other deaths are due to complications of splenic rupture, meningitis, myocarditis, hepatitis and disseminated lymphoproliferative disease.
V. Treatment.
There is no special treatment for this disease, mainly symptomatic treatment and supportive treatment.