Measles refers to acute viral infectious diseases, characterized by a combination of catarrhal symptoms with specific exanthema. The measles virus enters the body by airborne droplets. The incubation period lasts up to 2 weeks, sometimes up to 1 month. The catarrhal period of measles is manifested by cough, fever, cervical lymphadenitis. It is replaced by a period of rashes with the gradual appearance of rash elements characteristic of measles. Recovery begins 1-2 weeks after the onset of measles. Diagnosis of measles is carried out, as a rule, on the basis of clinical data. Treatment is mainly symptomatic, aimed at reducing body temperature, detoxification, increasing the body’s resistance.
Measles virus RNA-containing, belongs to the genus Morbillivirus. It is unstable in the external environment, inactivated during drying, exposure to sunlight, ultraviolet irradiation, when heated to 50 ° C. The virus is able to persist at room temperature for 1-2 days, when cooled (the temperature optimum for maintaining viability: from -15 to -20 ° C) remains active for several weeks.
The reservoir and source of infection is a sick person. The isolation of infection begins in the last 1-2 days of incubation, the entire prodromal period and continues for 4 days of the rash period. In some cases, the time of contagion is delayed up to 10 days from the appearance of the exanthema. There is no asymptomatic measles carrier.
The measles virus is transmitted by an aerosol mechanism by airborne droplets. The patient releases the pathogen into the environment during coughing, sneezing, just when exhaling air and talking. The fine suspension is carried with the air current through the room. Due to the weak resistance of the virus, the contact-household transmission path is excluded. When a pregnant woman is infected with measles, transplacental transmission of infection is possible.
People are extremely susceptible to measles, after the transfer, a lifetime of strained immunity remains. Usually the disease occurs in childhood, measles is rare in adults and is noticeably more severe. The peak incidence occurs in the winter-spring period, the minimum number of cases is recorded in August-September. The incidence of measles has significantly decreased recently due to routine vaccination of the population.
The virus enters the body through the mucous membrane of the upper respiratory tract, replicates in the cells of their integumentary epithelium and spreads through the body with blood flow, accumulating in the structures of the reticuloendothelial system. The measles virus has a tropicity to the integumentary tissues (skin, conjunctiva, mucous membranes of the oral cavity and respiratory tract).
In rare cases, it is possible to be affected by a brain virus with the development of measles encephalitis. The epithelium of the respiratory mucosa affected by the virus sometimes undergoes necrosis, opening access for bacterial infection. There is an opinion that the causative agent of measles can persist in the body for a long time, causing a slow infection that leads to systemic diseases (scleroderma, systemic lupus erythematosus, multiple sclerosis, etc.).
The incubation period of measles lasts 1-2 weeks, in cases of immunoglobulin administration it is extended to 3-4 weeks. A typical course of measles occurs with a sequential change of three stages: catarrhal, rashes and convalescence. The catarrhal period begins with a rise in temperature and the development of signs of general intoxication. Fever can reach extremely high numbers, patients complain of intense headache, insomnia, chills, pronounced weakness. In children, the symptoms of intoxication are largely smoothed out.
Against the background of intoxication syndrome, a dry cough appears in the first days, mucopurulent rhinorrhea, conjunctivitis (accompanied by intense swelling of the eyelids) with purulent discharge, photophobia is noted. In children, hyperemia of the pharynx is pronounced, the grain of the posterior wall of the pharynx, the face is puffy. In adults, catarrhal signs are less pronounced, but regional lymphadenitis may occur (mainly cervical lymph nodes are affected). Auscultation of the lungs marks hard breathing and dry wheezing. Sometimes the disease is accompanied by relaxation of intestinal activity, dyspeptic symptoms (nausea, vomiting, heartburn, belching).
The first fever wave is usually 3-5 days, after which the body temperature decreases. The next day, the temperature rises again and intoxication and catarrhal phenomena worsen, and Filatov-Koplik-Velsky spots are noted on the mucous membrane of the cheeks – a specific clinical sign of measles. The spots are located on the inner surface of the cheeks opposite the small molars (sometimes passing to the gum mucosa), represent slightly raised white areas above the surface, surrounded by a thin strip of hyperemic mucosa (a kind of “semolina porridge”). As a rule, when a rash appears, these spots disappear, in adults they can persist during the first days of the rash period. At the same time or a little earlier than the Filatov-Koplik-Velsky spots, an enanthema appears on the soft and partially hard palate, which is red spots with an irregular pinhead. After 1-2 days, they merge and cease to stand out against the background of general hyperemia of the mucosa.
The total duration of the catarrhal period is 3-5 days in children and about a week in adults. After that, a period of rash occurs. Measles rash initially forms on the scalp and behind the ears, spreads to the face and neck. By the second day, rashes cover the torso and shoulders. On the third day, the rash covers the limbs and begins to turn pale on the face. Such a sequence of rashes is characteristic of measles, is a significant sign for differential diagnosis.
The measles rash is a bright spotty-papular exanthema, prone to the formation of drain shaped groups with intervals of unchanged skin. The rash in adults is more pronounced than in children, with severe course it can acquire a hemorrhagic character. In the period of rashes, catarrhal symptoms increase and fever and intoxication worsen.
The period of convalescence occurs 7-10 days after the onset of the disease (in adults, the duration of measles is longer), clinical symptoms subside, body temperature normalizes, elements of the rash regress (similar to the order of appearance), leaving behind light brown areas of increased pigmentation that disappear after 5-7 days. At the site of pigmentation, bran-like peeling remains for some time (especially on the face). In the period of reconvalescence, there is a decrease in the immune factors of the body’s defense.
Mitigated measles is an atypical clinical form of infection occurring in passively or actively immunized individuals or those who have previously had measles. It is characterized by a longer incubation period, mild or absent symptoms of intoxication and a shortened period of catarrhal manifestations. There is a typical exanthema for measles, but rashes can appear immediately on all parts of the body or in the reverse (ascending from the limbs to the face) sequence. Filatov-Koplik-Velsky spots are often not detected.
Another atypical form is abortive measles – its onset is the same as in normal cases, but after 1-2 days the symptoms subside, the rash spreads to the face and trunk, after which it regresses. Fever in the abortive form usually occurs only on the first day of rashes. Sometimes, with the help of serological techniques, subclinical forms of measles are detected.
Measles is most often complicated by secondary bacterial pneumonia. In young children, the resulting inflammation of the larynx (laryngitis) and bronchi (bronchitis) sometimes lead to the development of false croup, threatening asphyxia. Sometimes stomatitis is noted.
In adults, measles can contribute to the development of meningitis and meningoencephalitis, as well as polyneuritis. A rare but rather dangerous complication is measles encephalitis. Currently, there is a theory of the development of autoimmune diseases, according to which the measles virus can take part in the pathogenesis of these conditions.
The diagnosis of measles is successfully carried out on the basis of clinical manifestations. A general blood test shows a picture characteristic of a viral infection: lymphocytosis on the background of moderate leukopenia (or the concentration of white blood cells remains within normal limits), plasmocytosis, increased ESR. In adults, there may be a reduced concentration of neutrophils and lymphocytes and the absence of eosinophils.
The results of specific bacteriological and serological studies (rarely used in clinical practice) are retrospective. If pneumonia is suspected, a lung radiography is required. With the development of neurological complications, a neurologist’s consultation, rheoencephalography, brain EEG is indicated for a patient with measles. A lumbar puncture may be indicated for the diagnosis of meningitis.
Measles is treated on an outpatient basis, patients with severe complicated course are hospitalized, or according to epidemiological indications. Bed rest is prescribed for the entire feverish period. Currently, no sufficiently effective etiotropic therapy has been developed, treatment consists in relieving symptoms and preventing complications. As a measure to reduce toxicosis, it is recommended to drink copious amounts. Intensive detoxification measures are carried out in cases of extremely severe course.
Patients should observe oral and eye hygiene, avoid bright light. Antihistamines, antipyretics, vitamins and adaptogens are prescribed as pathogenetic and symptomatic therapy. In the early stages of the disease, interferon intake significantly improves the course. In case of a threat of secondary infection, broad-spectrum antibiotics are prescribed. Measles encephalitis requires the appointment of high doses of prednisone and other intensive care measures.
Prognosis and prevention
Uncomplicated measles usually ends with complete recovery, there are no cosmetic defects after rashes. The prognosis may be unfavorable in case of measles encephalitis.
Specific measles prevention consists in routine vaccination of the population with a live measles vaccine. The first vaccination against measles is given to children at 12-15 months, revaccination is carried out at 6 years. Isolation of patients lasts up to 10 days, restriction of contact with unvaccinated and non-ill children – up to 21 days from the onset of the disease.