Infectious mononucleosis
Introduction
Introduction to infectious mononucleosis Infectious mononucleosis is an acute mononuclear-macrophage system proliferative disease with a self-limiting course. Clinical manifestations of irregular fever, lymphadenopathy, sore throat, peripheral blood mononuclear cells increased, and abnormal lymphocytes, heterophilic agglutination test positive, anti-EBV antibodies can be measured in serum. About half of the primary infections of EBV in young adults and adults show infectious mononucleosis. Burkittis lymphoma in African children (BL and nasopharyngeal carcinoma occur only in patients who have been infected with Epstein-Barr virus, and both Epstein-Barr virus DNA and virus-determined nuclear antigen are present in tumor cells of BL and nasopharyngeal carcinoma, so it is considered Epstein-Barr virus may be an important cause of BL and nasopharyngeal cancer. basic knowledge The proportion of sickness: 0.004% - 0.005% Susceptible people: more common in children and adolescents Mode of infection: respiratory transmission Complications: acute nephritis spleen rupture myocarditis
Cause
Infectious mononucleosis
Infectious mononucleosis is an acute infectious disease caused by Epstein-Barr virus (EBV) infection.
EBV is a lymphocyte-derived DNA virus belonging to the herpesvirus genus. It mainly invades B lymphocytes (the C3a receptor on the surface of B lymphocytes is the same as the EBV receptor). EBV has five antigenic components, each of which can produce its own corresponding Antibodies:
1 Capsid antigen (VCA): VCA IgM antibody appears early, disappears after 1-2 months, is a new sign of EBV infection, VCA IgG appears slightly later than the former, but can last for many years or life, so can not be distinguished New infections and past infections;
2 early antigen (EA): can be divided into diffuse component D and localized component R, which is an antigen formed by EBV at the beginning of the proliferative cycle. EA-D component only has EBV-specific DNA polymerase activity, and EAIgG antibody is a recent infection. Or the marker of active proliferation of EBV, the antibody reaches a peak at 3-4 weeks after the disease, lasting for 3-6 months;
3 core antigen (EBNA): EBNAIgG appears 3 to 4 weeks after the disease, lasts for a lifetime, is a sign of past infection;
4 lymphocyte-determined membrane antigen (LYDMA): a complement-binding antibody with the same appearance and duration as EBNA IgG and a marker of previous infection;
5 Membrane antigen (MA): is a neutralizing antigen that produces a corresponding neutralizing antibody with the same appearance and duration as EBNA IgG.
The disease occurs all over the world, mostly sporadic, can also cause a small epidemic, can occur all year round, from late autumn to early spring, patients and EBV carriers are the source of infection, the virus is abundant in salivary glands and saliva , sustainable or intermittent detoxification for several weeks, months or even years, the transmission route is mainly spread through close contact (spoken mouth), although droplet spread is possible, but it is not important, even through blood transfusion and Fecal transmission, the problem of intra-uterine transmission is still controversial, the disease is more common in children and adolescents, gender differences are not large, children under 6 years old are mostly recessive or light infections, more typical symptoms appear after infection over 15 years old, after onset Long-lasting immunity is available, and the second episode is rare.
Prevention
Infectious mononucleosis prevention
There is no effective preventive measure for this disease. It is recommended that the respiratory tract should be isolated in the acute phase. The respiratory secretions should be bleached, chloramine or boiled. However, it is considered that it is not necessary to isolate the patient. The viremia may be as long as the patient recovers. Month, so if it is a blood donor, the blood donation period must be extended to at least 6 months after the onset of the disease. The prevention of this disease is still under investigation.
Complication
Infectious mononucleosis complications Complications acute nephritis spleen rupture myocarditis
About 30% of patients can be complicated by pharyngeal hemolytic streptococcal infection, the incidence of acute nephritis can be as high as 13%, clinical manifestations like general nephritis, the incidence of spleen rupture is about 0.2%, usually more common in the disease within 10 to 21 days, about 6 % of patients have myocarditis.
Symptom
Symptoms of Infectious Mononucleosis Common Symptoms Maculopapular Hepatomegaly Liver Function Abnormal Hyperthermia Visible Small Hemorrhage Liver Spleen Mass Most Needle-like Spots Scarlet fever-like rash Superficial lymph node enlargement Lymph node enlargement
The incubation period ranges from 5 to 15 days, most of which are 10 days. The onset is urgent and slow, and nearly half have prodromal symptoms. The main symptoms are:
(1) In addition to extremely light cases, there are fevers, body temperature ranging from 38.5 to 40 °C, can be relaxation, irregular or missed type, heat range from several days to several weeks, the early stage of the disease may have relatively slow pulse .
(B) 60% of patients with lymphadenopathy have superficial lymphadenopathy, systemic lymph nodes can be involved, cervical lymph nodes are the most common, underarm, inguinal, second, thoracic, mediastinal, mesenteric lymph nodes can also be involved, diameter 1 ~ 4cm, medium hardness, dispersion without adhesion, no obvious tenderness, no suppuration, bilateral asymmetry, swollen lymph nodes subsided, usually within 3 weeks, even for a longer period of time.
(C) about half of the patients with angina have pharynx, uvula, tonsil and other congestion, edema or swelling, a small number of ulcers or pseudomembrane formation, patients with sore throat, small bleeding points visible in the ankle, gums can also be swollen And there are ulcers, throat and tracheal obstruction are rare.
(4) About 10% of cases of hepatosplenomegaly have hepatomegaly, 2/3 of patients with abnormal liver function, about 5% to 15% of jaundice, almost all cases have splenomegaly, mostly only under the costal margin 2 ~ 3cm, even spleen rupture can occur.
(5) About 10% of cases of rash have rash, pleomorphic, rash, scarlet fever-like rash, nodular erythema, urticaria, etc., occasionally hemorrhagic, more common in the trunk, less affected limbs, often Within 1 to 2 weeks after onset, 3 to 7 days subsided, leaving no traces, no desquamation, a typical mucosal rash, manifested as multiple needle-like defects, seen at the junction of soft and hard palate.
(6) Neurological symptoms The nervous system is rarely involved, manifested as acute aseptic meningitis, meningoencephalitis, brainstem encephalitis, peripheral neuritis, etc., clinical symptoms may appear, cerebrospinal fluid may be moderate Protein and lymphocytosis, and abnormal lymphocytes, the prognosis is mostly good, and those who are seriously ill will not leave sequelae after recovery.
The course of the disease varies from a few days to 6 months, but most of them are 1 to 3 weeks, occasionally recurrence, the course of recurrence is shorter, and the condition is mild. The disease course of a few cases can be delayed for several months or even years. It is called chronic active EB virus infection.
Examine
Infectious mononucleosis
(1) When the blood-borne disease starts, the white blood cell count can be normal. The total number of white blood cells often increases from 10 to 12 days after the onset, and the high one can reach 30,000 to 60,000/mm3. The third week returns to normal, and the first one in the onset Abnormal lymphocytes (10% to 20% or more) can occur in 21 days. According to their cell morphology, they can be divided into three types: foam type, irregular type, and naive type. This abnormal cell may originate from T cells. Found in other viral diseases, such as viral hepatitis, epidemic hemorrhagic fever, chickenpox, mumps, etc., but the percentage is generally less than 10%, platelet count can be reduced, very few patients have neutropenia or lymphopenia, may be The human body is associated with an abnormal immune response.
(2) The bone marrow is lack of diagnostic significance, but other diseases such as blood diseases may be excluded. There may be abnormal lymphocytes (which may be caused by dilution of peripheral blood), neutrophil nucleus shifts left, and reticular cells may proliferate.
(C) heterophilic agglutination test The positive rate of heterophilic agglutination test is 80% to 90%. The principle is that the patient's serum often contains antibodies belonging to IgM, which can be agglutinated with sheep red blood cells or horse red blood cells. For 2 to 5 months, those with late-onset antibodies often recover slowly. In a few cases (about 10%), the heterophilic agglutination test is always negative, mostly light, especially in children.
Normal people, patients with serum disease, and a small number of patients with lymphoblastoma, monocytic leukemia, tuberculosis, etc., may also have positive results in heterophilic agglutination tests (except for serum diseases, antibody titers are low), but available Guinea pig kidney and bovine erythrocyte absorption test to identify, normal people and the above-mentioned various patients (except for serum disease patients), blood heterophilic antibodies can be completely absorbed by the guinea pig kidney or partially absorbed by bovine red blood cells, and the patient's blood heterophilic antibody It can be partially absorbed by the guinea pig kidney and fully absorbed by bovine red blood cells, while the serum antibodies of serum patients can be completely absorbed by both. The heterophilic lectin titer has clinical value from 1:50 to 1:224, and its titer is generally considered to be More than 1:80 has diagnostic value. If the titer is increased by more than 4 times per week, the significance is greater. In recent years, the slide agglutination method is used to replace the sheep red blood cells with horse red blood cells, and the result is faster and more sensitive than the test tube method.
(IV) Determination of EB virus antibody After the human body is infected with Epstein-Barr virus, it can produce membrane shell antibody, anti-membrane antibody, early antibody, neutralizing antibody, complement-binding antibody, virus-related nuclear antibody and the like.
(5) Other EB virus cultures are rarely used in clinical practice. The determination of bovine erythrocyte hemolysin in serum has diagnostic value (potency is above 1:400). Autoantibodies can be detected in the acute phase of the disease, such as anti-i antibody (antigen) i is only in fetal cells), anti-nuclear antibodies, etc., anti-i condensation set high titer can cause auto-hemolytic anemia.
Diagnosis
Diagnosis and identification of infectious mononucleosis
diagnosis
The sporadic cases are easily overlooked. The diagnosis is based on clinical symptoms, typical blood picture and positive heterophilic agglutination test. In the future, the two are more important. When there is epidemic, epidemiological data has great reference value.
When it is difficult to carry out serological examination, the diagnosis can be made according to the combination of blood and blood. Although the clinical manifestations are high fever, angina, neck lymphadenopathy, etc., it is not necessary, and serum alanine aminotransferase is mostly elevated during the course of the disease. High, even if there is no jaundice, it is worthy of attention. The typical blood and heterophilic agglutination test is changed or positive on the 2nd day of the disease course, but the significant change is generally seen in the 1st to 2nd week. The heterophilic agglutination test is even in After a few months, it has risen to a meaningful level, so it is necessary to emphasize the importance of repeated examinations. One or two negative results cannot be denied.
The disease is widely distributed, mostly sporadic, and can also cause epidemics. Virus carriers and patients are the source of infection of this disease. Close contact with the mouth is the main route of transmission. Although droplet transmission is possible, it is not important. The age group of 15 to 30 years old is more than the age of 6 years old and most of them are inconspicuous infections. The disease occurs throughout the year, which seems to be more in the late autumn and early winter. After a disease, it can obtain longer-lasting immunity.
Differential diagnosis
The clinical manifestations of cytomegalovirus disease resemble this disease. The liver and splenomegaly are caused by the action of the virus on the target organ cells. Infectious mononucleosis is associated with lymphocyte proliferation, and the cytomegalovirus disease is swallowed. Pain and neck lymphadenopathy are rare. There is no heterophilic lectin and EB virus antibody in serum. The diagnosis depends on virus isolation and specific antibody determination. The disease also needs to be differentiated from acute lymphocytic leukemia. Bone marrow cytology examination There is a diagnosis value, the disease needs to be differentiated from acute infectious lymphocytosis in children, the latter is more common in young children, most of them have upper respiratory symptoms, lymph nodes are rare, no splenomegaly; the total number of white blood cells is increased, mainly mature lymph Cells, abnormal blood picture can be maintained for 4 to 5 weeks; heterophilic agglutination test is negative, no Epstein-Barr virus antibody appears in the serum, in addition, the disease should be differentiated from exudative tonsillitis caused by hepatitis A virus and streptococcus.
