Measles (measles, rubeola, morbilli) is an acute respiratory infection caused by measles virus, the main symptoms of which are fever, upper whistling tract infection, conjunctivitis, etc., and is characterized by the appearance of red macules on the skin and mucosal patches of measles on the buccal mucosa. The disease is highly contagious, in densely populated areas without universal vaccination is prone to epidemics, about 2 to 3 years a pandemic. In China, since 1965, after the start of the universal live attenuated measles vaccine, the pandemic has been controlled.
What causes measles?
Measles virus belongs to the family Paramyxoviridae and is a spherical particle with a diameter of about 100-250 nm and six structural proteins; it can be isolated in nasal secretions, blood and urine during the prodromal and rash periods. When cultured in human embryos or monkey kidney tissue for 5-10 days, the cells show pathological changes and multinucleated giant cells with intranuclear eosinophilic inclusion bodies are seen. Measles virus has only one serotype and is antigenically stable. The virus is not heat resistant and is sensitive to sunlight and disinfectants, but can be stored for long periods at low temperatures.
The virus is present in the secretions of the conjunctiva, nose, mouth, pharynx and trachea and is transmitted by droplets through sneezing, coughing and talking. The disease is highly contagious, with more than 90% of susceptible persons developing the disease after contact. It used to be prevalent in cities once every 2-3 years, with the highest incidence in children aged 1-5 years. After the use of live attenuated measles vaccine, the incidence has decreased, but the age of onset has shifted because immunity is not durable. The current incidence is more common in unvaccinated preschoolers, immune failed teens, and young adults, and can even form intra-community epidemics.
Infants receive maternal antibodies from the placenta and have passive immunity for 4-6 months after birth, after which they gradually disappear; although maternal antibodies in the blood of the vast majority of infants are undetectable by 9 months of age, some children can persist for up to 15 months, which can interfere with vaccination. Infants of susceptible mothers are not immune to measles and can get the disease before or after delivery.
When a susceptible person inhales nasopharyngeal secretions or droplets containing the virus, the measles virus multiplies in the local mucosa for a short period of time, while a small amount of virus invades the blood; thereafter, the virus replicates actively in the mononuclear macrophage system of distant organs, and enters the bloodstream in large numbers about the 5th to 7th day after infection, which is the clinical prodromal period. During this period, the virus can be found in the tissues of the child’s whole body, such as the epithelial cells of the whistle and lymphoid tissue, and in the nasopharyngeal secretions, urine, blood and other secretions and body fluids, which are the most infectious at this time. After the rash appears, virus replication decreases, and by day 16 after infection, only the virus in the urine can persist for several days. On the second day after the rash, the serum is almost 100% positive for antibodies and the clinical symptoms begin to improve significantly. The lymphocytes in the cerebral crest fluid of 10% of the children are significantly increased, and 50% have EEG changes at the peak of the disease, but only 0 or 1% have signs and symptoms of encephalitis, which often appear several days after the acute onset of the disease, when the antibodies in the serum are already high and the virus is no longer found. autoimmune encephalitis
What are the manifestations of measles and how is it diagnosed?
Clinical manifestations:
(a) Typical measles can be divided into the following four phases
1. Incubation period: generally 10-14 days, but also as short as about 1 week. During the incubation period there may be a mild increase in body temperature.
2, the prodromal phase: also known as the pre-rash, generally 3 to 4 days. The main manifestations of this phase are similar to the symptoms of upper whistle infection.
① fever, seen in all cases, mostly moderate fever or more;
(ii) cough, runny nose, lacrimation, pharyngeal congestion and other khat symptoms, highlighted by ocular symptoms, conjunctival inflammation, eyelid edema, increased tearing, photophobia, and a distinct congested horizontal line (Stimson line) at the edge of the lower eyelid, which is extremely helpful in diagnosing measles.
Koplik’s spots, which appear 24 to 48 hours before the onset of the rash, are small grayish white dots about 1,0 mm in diameter with a red halo around the outside, and are seen only on the buccal mucosa opposite the lower molars at first, but they increase quickly within a day and can involve the entire buccal mucosa and spread to the lip mucosa, and the mucosal rash can disappear gradually after the rash appears, leaving dark red dots;
Occasionally, skin urticaria, vague maculopapular rash or scarlet fever-like rash is seen, which disappears when the typical rash appears;
⑤ Some cases may have some non-specific symptoms, such as general malaise, loss of appetite, and lack of energy. Infants may have digestive system symptoms.
3. Rash phase: The rash mostly appears 3~4 days after the onset of fever. The rash starts as a sparse irregular red papule with normal skin between the rash, starting from behind the ear, neck, along the edge of the hairline, developing downward within 24 hours, spreading over the face, trunk and upper limbs, and on the third day the rash involves the lower limbs and feet, and in severe cases the rash often fuses, with edematous skin and puffy facial deformation. Most of the rash discolors when pressed, but petechiae may also appear. Lymph node enlargement and splenomegaly are present throughout the body and persist for several weeks, and mesenteric lymph node swelling may cause abdominal pain, diarrhea, and vomiting. Measles pathological changes in the mucosa of the appendix can cause symptoms of appendicitis. Delirium, agitation and lethargy are often present in the extreme phase of the disease, especially during hyperthermia, and are mostly transient, disappearing after the fever subsides, and are not associated with subsequent central nervous system comorbidities. During this period, there are wet rales in the lungs and increased lung texture is seen on X-ray.
4.Recovery period: The rash starts to subside 3~4 days after the rash appears, and the order of subside is the same as when the rash appears; in the absence of comorbidities, other symptoms such as appetite and spirit also improve. After the rash recedes, the skin is left with bran-like flaking and brown pigmentation, which heals in 7-10 days.
(B) other types of measles
1, mild measles: mostly seen in those who have received gammaglobulin or adult blood injections during the incubation period, or infants <8 months of age who still have antibodies in their mothers. The fever is low upper whistle symptoms are mild, measles mucosal spots are not obvious, the rash is sparse, the duration of the disease is about 1 week, no complications.
2, severe measles: fever up to 40 ℃ or more, toxic symptoms are heavy, with convulsions, coma. The rash is fused purple-blue, often with mucosal bleeding, such as rhinorrhea, vomiting, hemoptysis, hematuria, thrombocytopenia, etc., called black measles, may be a form of DIC; if the rash is less, dull color, often poor circulation performance. This type of children with high mortality.
3, no rash type measles: people who have been injected with live attenuated measles vaccine may not have typical mucosal spots and rash, or even no rash throughout the course of the disease. This type is not easy to diagnose, only dependent on the prodromal symptoms and serum measles antibody titers increased to confirm the diagnosis.
4, heterotypic measles: caused by inactivated vaccination. The manifestations are high fever, headache, myalgia, no oral mucosal spots; the rash starts from the distal extremities and extends to the trunk and face, and is polymorphic; it is often accompanied by edema and pneumonia. The inactivated measles vaccine is not used in China, so this type is rare.
5, adult measles: due to the application of measles vaccine, the incidence of measles in adults is gradually increasing, and children’s measles differ from: a high incidence of liver damage; gastrointestinal symptoms are common, such as nausea, vomiting, diarrhea and abdominal pain; skeletal myopathy, including joint and back pain; measles mucosal spots exist for a long time, up to 7 days, eye pain is common, but photophobia is rare.
Diagnosis:
Based on epidemiological data and clinical manifestations, the diagnosis of typical measles is not difficult. Measles mucosal plaques are extremely helpful for early diagnosis before rash emergence, and the upper whistle tract khat symptoms and rash morphological distribution characteristics are helpful for diagnosis; post-rash hyperpigmentation and bran-like desquamation have diagnostic significance in the recovery period.
What tests should be done for measles?
(a) peripheral blood picture: white blood cell count often drops to 4000-6000/mm3 during the rash period, especially in neutrophils.
(b) Smear of secretions for multinucleated giant cells: Smear of nasopharyngeal and ocular secretions and urine sediment, stained with Richter’s stain, and microscopically visible as detached epithelial multinucleated giant cells. It can be positive 1 to 2 days before and after the rash, earlier than the appearance of measles mucosal spots, which is helpful for early diagnosis.
(iii) Virological examination: application of fluorescently labeled specific antibodies to detect nasal mucosal blots or urine sediment can find measles antigens in epithelial cells or leukocytes, and positivity has diagnostic value. Early isolation of measles virus from nasopharyngeal and ocular secretions and blood leukocytes can confirm the diagnosis. A fourfold or greater increase in serum hemagglutination inhibition and complement binding antibodies during the recovery period or an antibody titer greater than 1:60 one month after onset of the disease can be useful for diagnosis. Specific IgM assay also has early diagnostic value.
How should measles be prevented?
Improving the immunity of the population is the key to preventing measles, so it is important to implement planned immunization for susceptible people. If measles patients are found, comprehensive measures should be taken to prevent transmission and epidemics.
(a) Automatic immunization: Susceptible persons should be vaccinated with live attenuated measles vaccine. The age of first vaccination should not be less than 8 months, because of the fear of antibodies from the mother to neutralize the vaccine virus, making it ineffective. China is currently scheduled for initial vaccination at 8 months of age and a booster at 4 years of age. Foreign countries advocate that initial vaccination at 15 months of age is more secure, and believe that those vaccinated within 1 year of age should receive a booster after 1 year. The vaccine should be stored in a dark place at 2-10℃, and each subcutaneous injection of 0.2ml is sufficient. The dose is the same for all ages, and it is best to vaccinate one month before the measles epidemic season. If a susceptible person receives the measles vaccine within 2 days of contact with a measles patient, the disease can still be prevented or mitigated by emergency vaccination. If 80% of susceptible persons are vaccinated at the time of the epidemic, the epidemic can be controlled within 2 weeks. Reactions after vaccination are mild, with a low-grade fever for several days after 5 to 14 days and an occasional sparse light red rash.
Those with fever and acute or chronic diseases should withhold autoimmunization; those with allergies, active tuberculosis, malignant tumors, leukemia, application of immunosuppressive or radiation therapy, and congenital immunodeficiency should not receive live attenuated measles vaccine; those who have received blood or blood products and passive immunization preparations within 8 weeks, and those who have received live attenuated vaccines against other viruses within 4 weeks should postpone vaccination to avoid affecting the effect.
After vaccination with live attenuated measles vaccine, serum antibodies rise, with a positive rate of 95% to 98%, and antibodies such as hemagglutination inhibition can appear in the blood as early as 12 days, peaking at 1 month, with antibody potency of 1:16 to 1:128. 2 to 6 months later, they gradually decline, but generally remain at a certain level. In some cases, the antibodies may disappear after 4-6 years, so the re-vaccination age can be 4-6 years. When the active immunization coverage of infants reaches 90% or more, a disease-free zone can be formed.
In some countries, measles vaccine, rubella vaccine and mumps vaccine are given at the same time, which does not affect their immunization effect.
(B) Passive immunization: Young, weak and sick people who come into contact with measles patients can be immunized from the disease within 5 days, while passive immunization within 5 to 9 days can only reduce the disease. Passive immunity can only be maintained for 3 to 4 weeks, after 3 weeks of exposure to measles patients need to be reinjected.
(C) comprehensive preventive measures: Measles patients found should be reported immediately for the epidemic, and entertain whistling isolation to 5 days after the rash, with complications extended to 10 days. Any susceptible children in contact with patients should be quarantined for 3 weeks and given automatic or passive immunization, depending on the situation, and those receiving immunization preparations should extend the quarantine to 4 weeks. During measles epidemics, patients should be vigorously promoted not to go out, medicine should be sent to the door, susceptible children should not suffer from the door, collective institutions should strengthen morning checks, and suspicious persons should be isolated and observed.
How should measles be treated?
No specific antiviral drugs have been found for measles virus, so treatment focuses on strengthening care, symptomatic management and prevention of complications.
(a) Care and symptomatic treatment: bed rest, isolation in a single room, fresh air in the living room, maintain the appropriate temperature and humidity, not too much clothing, eyes, nose, mouth and skin to keep clean. Diet should be nutritious and easy to digest, and more warm water should be fed. Do not avoid the mouth, and additional meals should be given during the recovery period. Small doses of antipyretics can be given in case of high fever, and cough suppressants should be given in case of severe cough. Weak and sick people can be given gammaglobulin early, a small amount of multiple transfusions of blood or plasma. In recent years, it has been reported that vitamin A supplementation to measles patients, 100,000 to 200,000 IU orally at a time, can reduce the disease and reduce the death rate.
(B) Traditional Chinese medicine treatment: when the first heat in the prodromal phase, the use of Xuanxuang published soup or Shengma Ge Gen Tang plus reduction, in order to pungent cool permeable table, to drive out the evil; external use of rash permeable medicine (raw ephedra, Guan Cai Zi, Xihe Liu, purple floating pine 15 grams each) into a cloth bag boiled in the bedside steam fumigation, or a little cooler to rub the face and limbs with the juice, to help the rash. During the rash period, it is advisable to clear heat and detoxify the rash, using clear heat and penetrate the surface of the soup, and for serious illness, using Sanhuang Shiyang Tang or Rhizoma Dihuang Tang. For weakness and cold extremities, use Ginseng Defeat Toxic Drink or Tonic Chinese and Beneficial Chlorine Tang. In the recovery period, it is advisable to nourish yin and clear heat, and use ablution ginseng and maitong soup or bamboo leaf and gypsum soup.
(C) Treatment of complications
1, pneumonia: treated as general pneumonia, secondary bacterial infections selected antibacterial drugs, severe cases can be considered short-term application of adrenal corticosteroids. Feeding less appropriate rehydration and supportive therapy.
2, laryngitis: maintain a certain humidity in the apartment and use steam inhalation several times a day to dilute the sputum. Select 1 or 2 antibacterial drugs, severe cases can be oral prednisone or dexamethasone intravenous drip. Keep quiet. If the laryngeal obstruction progresses rapidly, tracheal intubation or incision should be considered early.
3, cardiovascular insufficiency: early application of poisonous trichothecene or trichothecene cardiac proximate treatment in heart failure, can apply tachypnea diuretic at the same time. Control the total amount and rate of rehydration, maintain electrolyte balance, and if necessary, use energy combination (coenzyme A, adenosine triphosphate, cytochrome C) and vitamin C intravenous drip to protect the myocardium. Circulatory failure is treated as shock.
4, encephalitis: treatment as viral encephalitis, focusing on symptomatic treatment. The high fever is cooled, and in case of convulsions, anti-convulsants are used. Coma to enhance care. At present, there is no special treatment for subacute sclerosing encephalitis.