What Factors Can Cause a Measles Outbreak?

Measles is one of the most common acute respiratory infectious diseases in children. It is highly contagious and is prone to epidemics in densely populated areas without vaccines, with a pandemic in 2 to 3 years. Measles virus is a paramyxovirus that spreads through droplets of respiratory secretions. Clinically, it is characterized by fever, upper respiratory tract inflammation, ocular conjunctivitis, red maculopapular rash on the skin, and measles mucosal patches on the buccal mucosa. Pigmentation and bran-like desquamation are left behind after the rash. Recurrent respiratory diseases such as otitis media, laryngo-tracheitis, pneumonia, etc., severe complications such as measles encephalitis, subacute sclerosing panencephalitis and so on. There are currently no specific medications.

Basic Information

nickname: measles
English name: measles
Visiting department: Infectious Diseases
Multiple groups: child

Common causes: Measles virus infection
Common symptoms: Fever, upper respiratory tract inflammation, measles plaque, rash, etc.
Contagious: Have
way for spreading: Droplet spread

Causes of measles

Measles virus belongs to the family Paramyxoviridae and is a single-stranded negative-strand RNA virus. The diameter is about 100-250nm. There is a capsule outside the capsid, and the capsule has hemagglutinin (HL), which has hemolytic effect. There are six structural proteins of measles virus; measles virus can be isolated in nasal secretions, blood and urine during the prodromal and rash periods. Measles virus has only one serotype and is antigenically stable. The virus is not strong and is sensitive to dryness, sunlight, and high temperature. UV, peracetic acid, formaldehyde, lactic acid, and ether all kill measles virus, but can survive for a long time at low temperature.

Clinical manifestations of measles

1. Typical measles can be divided into the following four stages

(1) The incubation period is about 10 days (6-18 days). Children who have been exposed to measles or who have received passive immunization during the incubation period can be extended to 3-4 weeks. There may be a slight increase in body temperature during the incubation period.

(2) The prodromal period is also called the pre-eruption period, usually 3 to 4 days. The performance is similar to the symptoms of upper respiratory infections: fever is seen in all cases, mostly moderate to high fever; cough, runny nose, tears, congestion of the pharynx, etc., with prominent eye symptoms, conjunctival inflammation, eyelid edema, increased tears, photophobia, A sharp congestion line (Stimson line) on the edge of the lower eyelid is extremely helpful in the diagnosis of measles. Measles plaque, which appears 24 to 48 hours before the rash, is a small off-white spot with a diameter of about 1.0 mm and a red halo outside. It starts to be seen only on the buccal mucosa facing the lower molars, but it increases quickly within a day. It can affect the entire buccal mucosa and spread to the lip mucosa. Mucosal rash will gradually disappear after the rash appears, and there will be dark red dots. Occasionally, skin urticaria, faint macula or scarlet fever-like rash will disappear when a typical rash appears. ; Some cases may have some non-specific symptoms, such as general discomfort, loss of appetite, and lack of energy. But the temperature dropped slightly. Babies may have symptoms of digestive system, vomiting, diarrhea, etc.

(3) The rash usually appears 3-4 days after the fever. Body temperature can suddenly rise to 40 ~ 40.5 , the rash is a sparse and irregular red maculopapular rash, the skin between the rashes is normal, and the sequence of rashes is also characteristic: it starts from behind the ears, neck, along the edge of the hairline, and downwards within 24 hours It developed throughout the face, trunk, and upper limbs, and the rash affected the lower limbs and feet on the third day. In severe cases, rashes often merge, skin edema, and facial edema are deformed. Most of the skin rashes are discolored, but there are also spots. Lymphadenopathy and splenomegaly throughout the body persist for several weeks. Mesenteric lymphadenopathy can cause abdominal pain, diarrhea, and vomiting. Pathological changes of the measles of the appendix mucosa can cause appendicitis symptoms. In the extreme stage of the disease, especially high fever, there is often delirium, irritability and drowsiness. Most of them are transient and disappear after the fever recedes, which has nothing to do with the central nervous system complications later. During this period there were wet rales in the lungs, and X-ray examination showed increased lung texture.

(4) The rash started to resolve 3 to 4 days after the rash occurred in the recovery period , and the order of the rash resolved was the same as that at the time of the rash. In the absence of comorbidities, other symptoms such as appetite and mentality also improved, and the temperature decreased. Dark skin. After the rash subsided, bran-like desquamation and brown pigmentation remained on the skin, and healed in 7-10 days.

2. Other types of measles

(1) Mild measles virus-reduced measles virus infection is more common in those who have received gamma globulin injections during the incubation period, or infants who have mother antibodies in their bodies less than 8 months old. Low fever and mild upper respiratory symptoms. The measles plaques are not obvious and the rash is thin. The course of disease was about 1 week without complications.

(2) Severe measles fever can be as high as 40 ° C or above, severe poisoning symptoms, convulsions, and coma. Those who have a rash with a purple-blue coloration often have mucosal bleeding, such as nosebleeds, vomiting, hemoptysis, hematuria, and thrombocytopenia, which are called measles. Less rash, dull color, often poor circulation. This type of child has a high mortality rate.

(3) People with measles-free measles who have been injected with a live attenuated measles vaccine can have no typical mucosal plaques and rashes, or even no rashes throughout the course of the disease. This type of clinical diagnosis is difficult and can only be confirmed by relying on prodromal symptoms and increased measles antibody titers in the serum.

(4) Atypical measles This is atypical measles, caused by inoculation with inactivated vaccine. Presented with high fever, headache, myalgia, and no oral mucosal plaques. Visiting sequence: The rash extends from the distal limbs to the trunk and face, and is pleomorphic; often accompanied by edema and pneumonia. 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 adult measles has gradually increased. Differences from measles in children: high incidence of liver damage; more common gastrointestinal symptoms, such as nausea, vomiting, diarrhea and abdominal pain; skeletal muscle disease, including joint and back pain; measles plaques can persist for up to 7 days Eye pain is more common, but photophobia is rare.

3. Complications

(1) Laryngeal, tracheal, and bronchitis measles virus itself can cause inflammation of the entire respiratory tract. As children under 3 years old have a narrow larynx, rich mucosal blood vessels, and loose connective tissue, such as secondary bacterial or viral infections can cause respiratory tract obstruction. Clinical manifestations include hoarseness, bark-like cough, inspiratory dyspnea, and tricuspid sign. In severe cases, it can suffocate to death.

(2) Pneumonia Interstitial pneumonia caused by measles virus. Bronchial pneumonia is more common and is caused by secondary bacterial infections. Common pathogenic bacteria include Streptococcus pneumoniae, Streptococcus, Staphylococcus aureus, and Haemophilus influenzae, etc., so they are prone to empyema or pneumothorax. AIDS patients with measles pneumonia are often fatal.

(3) Myocarditis is rare, but transient ECG changes are common.

(4) Nervous system complications The incidence of measles encephalitis is low, and 1 to 2 out of 1,000 children with measles disease have this disease. Fever, fever, headache, drowsiness, convulsions, sudden coma and other symptoms are usually 2 to 5 days after the rash. Peripheral blood white blood cells increased, cerebrospinal fluid changes: light, moderately increased cells, mainly lymphocytes, increased protein, normal sugar. The case fatality rate is 10% to 25%; 20% to 50% of survivors have sports, intelligence or mental sequelae. Subacute sclerosing panencephalitis is a delayed complication of acute infection, which is manifested by a gradual decline in brain function, a serious condition, and a poor prognosis. But the incidence is extremely low, about one in a million; there is a typical history of measles 4 to 8 years before the onset of neurological symptoms, and it has fully recovered. 85% of the onset is 5 to 15 years old, the symptoms are very concealed, there are slight behavioral changes and learning disabilities, then mental retardation, and symmetrical, repetitive myoclonus, with an interval of 5 to 10 seconds; as the disease progresses, it appears A variety of abnormal motor and neurological dysfunctions include ataxia, retinopathy, optic nerve atrophy, etc .; finally, it develops into stiffness, coma, autonomic dysfunction, and denervation of the brain. The course of the disease varies, and most patients die 1 to 3 years after diagnosis. Individuals can survive for more than 10 years. Other Guillain-Barre syndromes, hemiplegia, cerebral thrombophlebitis and posterior optic neuritis are rare.

(5) The immune response of children with measles exacerbated by tuberculosis is temporarily suppressed, and the delayed skin hypersensitivity reaction to tuberculin disappears, which can last for several weeks, turning the original latent tuberculosis lesion into an active lesion, and the clinical manifestations of tuberculosis appear. , And even spread and cause miliary tuberculosis or tuberculous meningitis.

(6) Malnutrition and Vitamin A Deficiency In the process of measles due to high fever and loss of appetite, children's nutritional status can become poor and thin; common vitamin A deficiency, cornea appears cloudy, softened, and develops rapidly, leading to blindness.

4. New features of measles

After implementing immunization in China, the incidence and mortality of measles have been significantly reduced, and the measles pandemic has been basically controlled. However, due to the increase in population flow, missed vaccination or immunization failure of some children with measles vaccine, and the gradual decline in immunity with age after the initial immunization, the measles epidemic occurred at a small scale and showed the following new characteristics. After the age of onset, the incidence of measles is mostly children under 5 years old, especially those aged 1 to 2 years old. Most people with measles now are infants less than 8 months old and school-age children over 7 years old, with occasional illness in adults. Symptoms of measles poisoning are severe in adults, with fever ranging from 39 ° C to 40 ° C, measles mucosal plaques, and half of the patients have a tendency to rash bleeding, often accompanied by symptoms such as lethargy, but with fewer complications and a good prognosis.

Mild or atypical patients increase, rash is more common in maculopapular rash, and there may be other forms of rash such as herpes, bleeding spot-like rash and so on. Symptoms of fever, upper respiratory tract inflammation, and systemic poisoning were mild, and there were often no measles plaques. The rash appears first from the extremities and gradually develops toward the chest and back.

The onset season of measles is from October to February of the following year. After the measles vaccine is popularized, it will be moved to March to May every year.

A small number of people develop a second measles, more often than two years after the first measles. When the rash first appeared, the younger people or the early injection of gamma globulin or other reasons failed to stimulate the body to produce sufficient and long-lasting immunity, so when encountering wild measles strains, they will be infected again.

Measles diagnosis

According to the clinical manifestations of children: persistent fever, sore throat, photophobia, tearing, conjunctival redness and swelling. Measles plaques were seen at the buccal mucosa.

About 4 days of fever, red spot papules appeared on the skin. The order of visits was behind the ears, neck, then the torso, and finally the hands and feet of the limbs. After the rash, the skin is desquamated and pigmented. History of contact with measles patients 2 weeks ago. Easier to make a diagnosis. Early detection of multinucleated giant cells in nasopharyngeal secretions and detection of inclusion body cells in urine is helpful for early diagnosis. Serum measles antibodies should be tested on the first or second day after the rash.

Differential diagnosis of measles

Should be distinguished from fever, outbreaks and other diseases such as scarlet fever, rubella, and infantile rash.

Measles treatment

General treatment

Isolate, rest in bed, maintain proper temperature and humidity in the room, and always ventilate to keep the air fresh. When there is photophobia, the light in the room should be soft; give easy-to-digest nutritious foods and add sufficient water; keep the skin and mucous membranes clean, and keep the mouth moist and clean. Rinse mouth with saline and repeat several times a day. Once a rash appears in the palms of the hands, feet, feet, and feet, it means that the rash has gone out and the patient has entered the recovery period. Closely observe the condition, see a doctor immediately if comorbidities occur.

Symptomatic treatment

A small amount of antipyretics can be used in high fever; sedatives such as phenobarbital can be appropriately given for irritability; antitussive and antipyretic agents can be used in severe cough; antibiotics can be given to secondary bacterial infections. Children with measles require a large amount of vitamin A. The World Health Organization recommends that children with measles in vitamin A deficiency areas should be supplemented with vitamin A.

3. Chinese medicine treatment.

Measles prevention

Passive immunity

Immunized with serum globulin within 5 days after exposure to measles can prevent the onset of measles; the above effects cannot be achieved beyond 6 days. The clinical course of those who have used immune seroglobin changes greatly, the incubation period is long, the symptoms and signs are atypical, but it is still potentially infectious to contacts. Passive immunization can only be maintained for 8 weeks, and active immunization measures should be taken in the future.

2. Active immunity

The use of live attenuated measles vaccine is an important measure to prevent measles, and its preventive effect can reach 90%. Although 5% -15% of vaccinated children may have mild reactions such as fever, discomfort, and weakness, and a few will have rash after fever, but there will be no secondary bacterial infection and no neurological complications. Domestic regulations stipulate that the initial seeding age is 8 months. If the application is premature, the mother antibodies remaining in the baby will neutralize the immune effect of the vaccine. Because the seroconversion rate is not 100% after immunization, and the immune effect becomes weaker over time, the measles vaccine should be vaccinated a second time at the age of 4 to 6 or 11 to 12; young people who enter the university should be given measles again Immunity. Patients with acute tuberculosis infection should be treated with tuberculosis at the same time as the need for measles vaccine.

3. Control the source of infection

To achieve early detection and early isolation. Generally, patients are isolated to 5 days after the rash, and those with pneumonia are extended to 10 days. Those who are susceptible to measles should be quarantined and observed for 3 weeks.

4. Cut off the route of transmission

Patient clothing should be exposed to the sun. Patients should have ventilated rooms and exposed to ultraviolet light. In the popular season, do a good job of propaganda work, and susceptible children should go to public places as little as possible.