Measles

Measles is a highly contagious viral infection that is more common in children. It is characterized by fever, cough, rhinitis, conjunctivitis, enanthema (Koplik spots) on the mucous membrane of the cheeks or lips and maculo-papular rash, which spreads from top to bottom. The diagnosis is made on the basis of the clinic. Symptomatic treatment. There is an effective vaccine against measles.

 
Measles is widespread in the world, about 30–40 million cases annually, and about 800,000 children die from measles. In the US, the number of cases is significantly less, since vaccination is carried out; about 100-300 cases are registered annually.

ICD-10 codes

• Q05 Measles.
  • Q05.0. Measles, complicated by encephalitis.
  • Q05.1. Measles complicated by meningitis.
  • Q05.2. Measles complicated by pneumonia.
  • Q05.3. Measles complicated by otitis.
  • Q05.4. Measles with intestinal complications.
  • Q05.8. Measles with other complications (keratitis).
  • Q05.9. Measles without complications.

[1], [2]

Epidemiology of measles

A sick person is the source of the pathogen and at the same time a reservoir for it. The contagiousness index is 95-96%.

Patients are contagious within 1-2 days before the first symptoms of measles appear and until the end of 4 days from the onset of the rash. With the development of complications in the form of pneumonia increases the timing of virus isolation. The path of transmission of measles is airborne. Infection is possible even with short-term contact. From the source, a virus with airflows through the ventilation passages can spread to other rooms. Persons who do not have measles and are not vaccinated against it. Remain highly susceptible to the pathogen throughout life and can get sick at any age. Prior to the introduction of measles vaccination, 95% of children had measles before the age of 16 years. In recent years, children younger than 6 years of age suffer from measles. The highest mortality was observed in children of the first 2 years of life and adults. A large number of cases are noted among schoolchildren, adolescents, conscripts, students, etc. This is associated with a significant decrease in immunity 10–15 years after immunization. Measles outbreaks are also possible among those vaccinated (67-70% of all outbreaks).

Measles is widespread; in natural conditions only people are ill, in the experiment possible infection of primates. Prior to vaccination, measles outbreaks were recorded every 2 years. After the introduction of mass vaccination and revaccination, the periods of epidemiological well-being became longer (8-9 years). Measles are characterized by winter and spring seasonality of morbidity, with measles being the last to fall ill.

So far in a number of countries, measles is in the first place in the general infectious morbidity of the population. According to WHO, there are up to 30 million cases of measles in the world every year, of which more than 500,000 are fatal.

After suffering a natural measles infection, persistent immunity remains.

Repeated diseases are rare. Immunity after vaccination is more short-term (10 years after vaccination, only 36% of the vaccinated have protective antibody titers).

[4], [6], [7], [9], [10], [11], [12],

What causes measles?

Measles is caused by the paramyxovirus. This is a highly contagious infection transmitted by airborne droplets through secrets from the nose, throat, mouth during prodrome and in the early period of rash. The most infectious period lasts several days before the rash and several days after the rash appears. Measles is not contagious when a rash appears.

Newborns whose mothers have measles get protective antibodies transplacentally, which provide immunity for the first year of life. A postponed infection provides lifelong immunity. In the US, most cases of measles are brought in by immigrants.

Pathogenesis

The entrance gate of the infection is the mucous membrane of the upper respiratory tract. The virus multiplies in epithelial cells, in particular, in the epithelium of the respiratory tract. Electron microscopy of material taken from the spots of Filatov-Belsky-Koplik and skin lesions reveals accumulations of the virus. From the last days of incubation, the virus can be isolated from the blood within 1-2 days after the appearance of the rash. The causative agent is hematogenously spread throughout the body, fixed in the organs of the reticuloendothelial system, where it multiplies and accumulates. At the end of the incubation period, a second, more intense wave of viremia is observed. The pathogen has a pronounced epitheliotropic and affects the skin, conjunctiva, mucous membranes of the respiratory tract, oral cavity (spots Filatov-Belsky-Koplik) and intestines. The measles virus can also be found in the mucous membrane of the trachea, bronchi, sometimes in the urine.

[15], [16], [17], [18], [19], [23], [24], [25], [26], [27],

Symptoms of measles

The incubation period of the disease is 10-14 days, after which the prodromal period begins, which is characterized by fever, catarrhal symptoms, dry cough and tarsal conjunctivitis. Pathognomonic Koplika spots that appear on the 2-4th day of the disease, usually on the mucous membrane of the cheek opposite the 1st and 2nd upper molars. They look like white grains surrounded by a red areola. They can spread, turning into a common erythema on the entire surface of the cheek mucosa. Sometimes spread to the pharynx.

Separate symptoms are observed from the second half of the incubation period (weight loss, edema of the lower eyelid, conjunctival hyperemia, subfebrile in the evening, cough, runny nose).

The rash appears on the 3-5th day after the onset of the initial symptoms and on the 1-2th day after the appearance of Koplik spots. A macula-like rash first appears on the face and then goes down the sides of the neck, acquiring the character of maculo-papular. After 24-48 hours, the rash spreads to the trunk and extremities, including the palms and soles, gradually fading away on the face. In severe cases, there may be a petechial rash and ecchymosis.

During the height of the disease, the temperature reaches 40 ° C with the appearance of periorbital edema, conjunctivitis, photophobia, dry cough, profuse rash, prostration and slight itching. Common symptoms and signs correlate with rashes and a period of infectiousness. By the 3-5th day, the temperature decreases, the patient's state of health improves, the rash begins to fade quickly, leaving a copper-brown pigmentation, followed by peeling.

Immunocompromised patients may develop severe pneumonia and may not have a rash.

Atypical measles can be observed in patients who have previously been immunized with a vaccine containing killed measles virus that has not been used since 1968. Older vaccines can change the course of the disease. Atypical measles can begin suddenly, with high fever, prostration, headache, cough, abdominal pain. A rash may appear after 1-2 days, often starting on the extremities, may be maculopapular, vesicular, urticarial, or hemorrhagic. Swelling of the hands and feet may develop. Common are pneumonia and lymphadenopathy, which can last for a long time; changes on radiographs can stay for weeks and months. Signs of hypoxemia may appear.

Bacterial superinfection is characterized by pneumonia, otitis media and other lesions. Measles inhibits delayed hypersensitivity, which worsens the course of active tuberculosis, temporarily levels skin reactions to tuberculin and histoplasmin. Bacterial complications can be suspected by the presence of focal symptoms or recurrence of fever, leukocytosis, prostration.

After the resolution of the infection, acute thrombocytopenic purpura may occur, which leads to the development of bleeding, which can sometimes be severe.

Encephalitis develops in 1 / 1000-2000 cases, usually 2-7 days after the onset of the rash, often starting with high fever, headache, seizures and coma. In the cerebrospinal fluid, the number of lymphocytes is 50-500 / μl, moderately elevated protein, but may be the norm. Encephalitis may resolve for 1 week, but may last longer, resulting in death.

[29], [30], [31]

Measles diagnosis

In conditions of low incidence of Diagnosis of measles is complex and involves the assessment of the epidemic situation in the patient's environment, clinical observation in the dynamics and serological examination.

Typical measles can be suspected in a patient with symptoms of a runny nose, conjunctivitis, photophobia and cough if he has had contact with the patient, but usually the diagnosis is suspected after the onset of the rash. Diagnosis is usually clinical, based on the detection of Koplik spots or a rash. Complete blood count is not mandatory, but if it is done, you can detect leukopenia with relative lymphocytosis. Laboratory diagnosis of measles is necessary for controlling outbreaks and is rarely done. It comes down to the detection of IgM class of measles antibodies in serum or epitheral cells in nasopharyngeal and urethral washes (in urine) stained by immunofluorescence using PCR analysis of pharyngeal swabs or urine samples or by culture. Increased IgG levels in paired sera is an accurate, but late diagnostic method. Differential diagnosis of measles is carried out with rubella, scarlet fever, medicinal rashes (for example, when taking sulfonamides and phenobarbital), serum sickness, neonatal roseola, infectious mononucleosis, infectious erythema, and ECHO-coxsa virus infection. Atypical measles due to variability of symptoms can simulate a greater number of diseases. Signs for which rubella differs from typical measles include the absence of pronounced prodroma, the absence of fever or a slight fever, an increase (usually mild) of the parotid and occipital lymph nodes, and a short course. Drug rash often resembles a measles rash, but there is no prodrome, there is no staginess of rashes from the top down, cough and the corresponding epidemiological history. Roseola neonatal rare in children over 3 years; while there is a high temperature at the onset of the disease, lack of Koplik spots and malaise, the rash appears at the same time.

[32], [34], [35], [36]

Measles treatment

Mortality in the United States is about 2/1000, but in developing countries is higher, which is predisposed to nutritional deficiencies and vitamin A deficiency. In high-risk populations, an additional intake of vitamin A is recommended.

Suspected measles cases should be immediately reported to local or state health authorities, without waiting for laboratory confirmation.

Treatment of measles is symptomatic, even with encephalitis. Prescribing a vitamin reduces morbidity and mortality in children with low nutrition, but in others it is not necessary. For children older than 1 year with visual impairment due to vitamin A deficiency, 200,000 IU is prescribed orally daily for 2 days and repeated after 4 weeks. Children living in regions with vitamin A deficiency receive it once in a single dose of 200,000 IU. Children aged 4-6 months prescribed a single dose of 100 000 ME.

[37], [38], [39],

How to prevent measles?

Measles can be prevented with measles vaccine. Modern measles vaccines have preventive efficacy of 95-98%.

In most developed countries, children are prescribed a live attenuated vaccine. The first dose is recommended at the age of 12-15 months, but during an outbreak of measles, it can also be given for 6 months. 2 doses are recommended. Children immunized at the age of less than 1 year will need another double vaccination in the 2nd year of life. Vaccination provides long-lasting immunity and has reduced the incidence of measles in the United States by 99%. The vaccine causes lung or inapparent forms of the disease. Fever more than 38 ° C within 5-12 days after vaccination occurs in less than 5% of those vaccinated, followed by a rash. Reactions from the central nervous system are extremely rare; the vaccine does not cause autism.

Modern vaccines national vaccination calendar:

• Live measles vaccine culture dry (Russia).
• Vaccination against measles, mumps and rubella
• Ruvax live measles vaccine (France).
• MMR-II live measles, mumps and rubella vaccine (Netherlands).
• Priorix live measles, mumps and rubella vaccine (Belgium).

A microencapsulated live measles vaccine is currently undergoing preclinical testing, and a measles DNA vaccine is under study.

Contraindications to measles vaccination are: systemic tumors (leukemia, lymphoma), immunodeficiencies, treatment with immunosuppressants, such as glucocorticoids, alkylating agents, antimetabolites, radiation therapy. HIV infection is contraindicated only if there is a pronounced immunosuppression (stage 3 for CDC with CD4 less than 15%). Otherwise, the risk of catching a wild strain outweighs the risk of getting sick from a live vaccine. Vaccination should be otstrochena in pregnant women, fevers, patients with active untreated tuberculosis, or if used antibodies (whole blood, plasma or other immunoglobulins). The duration of the delay depends on the type and dose of immunoglobulin, but can be up to 11 months.

Measles-susceptible children and adults in the case of contact with the patient in the absence of contraindications are immunized with live measles vaccine, but no later than 72 hours after the alleged contact. With a longer term from the time of the alleged infection, as well as weakened persons or having contraindications to the administration of live measles vaccine, a normal human immunoglobulin is shown. Immunoglobulin, administered intramuscularly in the first 6 days after infection, protects against measles or facilitates its course.

The method of non-specific prophylaxis is the early isolation of the patient in order to prevent the further spread of the disease. Patients are subject to isolation for 7 days, with the development of complications - 17 days from the onset of the disease.

Children who have not been vaccinated and have not been ill, who have come into contact with measles patients, are not allowed into children's institutions for 17 days from the moment of contact, and who received prophylactically immunoglobulin - 21 days. The first 7 days from the start of contact children are not subject to separation.

Emergency measles prevention is possible if it is administered within 3 days after contact with measles. If vaccination is delayed, serum immunoglobulin is administered at a dose of 0.25 ml / kg intramuscularly (maximum dose 15 ml) immediately, followed by vaccination 5-6 months later with no contraindications. Upon contact with a sick patient with immunodeficiency, which is contraindicated in vaccination, serum immunoglobulin is administered in a dose of 0.5 ml / kg intramuscularly (maximum 15 ml). Immunoglobulins should not be administered simultaneously with the vaccine.

[41], [42], [43]

What is the prognosis for measles?

Measles has a favorable prognosis in the case of an uncomplicated course of the disease. With the development of giant cell pneumonia, encephalitis, inadequate late treatment, death is possible. In the case of the development of subacute sclerosing panencephalitis, measles in all cases has an unfavorable outcome.

[45], [46], [47],