ACUTE RESPIRATORY VIRAL DISEASES

PARAGRIPPAL INFECTION

Paragrippe is an acute viral disease, accompanied with moderate intoxication and affection of the respiratory tract with the predomination of laryngitis.

The problem is urgent because the paragrippal infections constitute an essential part of the acute respiratory diseases with a viral etiology. The age structure of the sickness rate indicates that a considerable percentage of cases is primarily registered among children and a lower percentage among the adults. Such complications as the development of laryngitis with croup and pneumonia in some cases are dangerous for a patient's life. In spite of the achieved success in studying this infection, the problems of the disease pathogenesis and especially, prophylaxis cannot be considerably investigated.

' Historic reference

In 1952 in the Japanese city of Senday N.Kuroga isolated the hemagglutinin virus from the lungs of a newborn child who had died from pneumonia and named it "Senday" virus. In 1954 in the USA R.Chanock isolated the CA virus (croup associated) from a patient with croup. In 1958 the same researcher isolated two more viruses which adsorbed erythrocytes on the infected cells and named them hemadsorption viruses (HA-1 and HA-2). All the three isolated viruses had similarities with the influenza virus, that is why they were called paragrippal in 1959. In 1960 K.Johnson and his co-authors isolated another similar virus and named it M-25.

Etiology

Nowadays paragrippal viruses are divided into four antigen types. The antigenic differences are based on the structural peculiarities of the superficial nucleocapsid antigens. The viral genome consists of the single-lane RNA. These viruses quickly die in the environment. They endure freezing well. The ultraviolet rays are destructive to them.

Epidemiology

The paragrippal viruses of the human are widely spread pathogens of the acute respiratory diseases, including the tropics. They circulate both among adults and children. The etiologic meaning of the paragrippal infection in the pathology of the respiratory tract reaches its maximum value in children under 3 years of age and progressively decreases in senior children.

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The human society is a reservoir of the infection, there is always a certain number of patients who keep or spread the infection. The infection is airborne. A sick person most intensively secretes the pathogen during the first 2-3 days of the disease. In case of a lingering course the secretion is prolonged. The duration of a patient's secretion of the virus into the environment lasts from 3 to 10 days. The symptomless carriage is extremely rare. The infection occurs during the direct contact. The virus spreads with big aerosol particles or slime drops and it retains infection on the objects around the patient for a long time, however, the oral infection is not of considerable importance. The disease occurs in the form of sporadic cases and local outbursts. Epidemics have not been described. All age groups are susceptible to the disease. The disease is registered all the year round.

Pathogenesis

All the four virus types are pathogenic for humans. The pathomorphologic data are very limited as the disease usually ends with full healing.

The entering gate and the main reproduction place of the viruses is the cylindrical epithelium of the upper respiratory tract. The inflammatory process in them is characterized by a slow development. The viruses have a special tropism to the mucous membrane of the pharynx and cause its edema and swelling. There is hyperplasia of the epithelium, its nuclei become bigger and lighter. During the acute stage on the 4-5th day there is an expressed leukocyte infiltration of the epithelium with small foci of degeneration.

Anatomic pathology

One of the most characteristic symptoms of paragrippe is a peculiar growing of the epithelium mostly in the medium and small bronchus. Along with the abundant pillow like growth of the bronchus epithelium, there is some smaller papillary growth. In most patients with paragrippe there is a greatly expressed peribronchial lymphoid infiltration. As a rule, pneumonia has a small-foci character and is observed in the spots of the expressed cells proliferation with follicle nuclei. Pneumonia in paragrippe, in contrast to influenza and its combinations, has a purulent nature, as well as bronchitis.

The affection of the nervous system in paragrippe does not occur very often but it is not something extraordinary. Serous meningitis, meningoencephalitis, polyneuritis and neuritis of the facial nerve have been described in children.

Clinical manifestations

The duration of the incubation period lasts from several hours to 7 days and depends on the virus type. Thus in type 1 it is more prolonged - up to 5-6 days and in type 3 it is shorter - 1-3 days. In the typical cases the disease develops gradually, the temperature rises up to the subfebrile and only in 3-4 days reaches 39 °Ñ.

During the first days in adults the intoxication is not well expressed and it reveals in a slight indisposition, often without a fever, dryness and burning in the

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nasopharynx, hoarse voice, stuffed nose, running nose and sometimes catarrhal conjunctivitis. In the little children along with the mild forms there are more often moderate and severe forms with the affection of the respiratory tract revealed in the form of bronchitis or pneumonia. In the paragrippal infections the severity of the course and the diffusion of the process considerably depends on the age and the premorbid condition of the patients. The disease takes the most severe course in newborn babies and in children during the first months of life.

During the following days in many patients the inflammatory process gets down the respiratory tract. Pharyngitis is often observed, it is manifested by hyperemia of the pharynx mucous membrane and painful swallowing. Most authors consider laryngitis with slightly expressed stenosis to be the most typical manifestation of the paragrippal infection.

In the mild courses of the disease the symptoms of laryngitis are manifested by a sore throat dry rough cough, burning in the trachea without clinical symptoms of bronchitis. The voice becomes hoarse. The fever is within the limits of 37.5-38 °Ñ. The outcome is favorable in case of the timely treatment. However, the manifestations of laryngitis may intensively increase and stenosis of the pharynx develops. Stenosis is clinically manifested by a labored loud breathing with a more or less expressed retraction of the pliable areas of the thorax and epigastrium. Croup is often the main and only manifestation of the disease. As a manifestation of the main disease, croup develops during the first 1-2 days with the temperature increase up to 38.5-39 °Ñ and a rough barking cough. Only in case of the croup viral nature, there is hyperemia of the mucous membrane of the larynx, especially in the infraglottica area edema and plethora. The mucous membrane is covered with blurred mucous. The course of the viral nature croup without joining the bacterial flora is usually favorable.

As a rule, the severe forms of croup are observed in case of the mixed viral-bacterial infection, when descending obturating stenotic laryngobronchitis develops. In the pathogenesis of stenotic laryngotracheobronchitis it is not the constriction of the glottis caused by the inflammatory changes in the infraglottica area that is of main importance, but the obstruction of the lower respiratory tract because of the fibrinous-necrotic process caused by joining the secondary bacterial flora. The croup course in such cases is undulating with a long lasting high temperature, expressed shortness of breath. Viscous sputum forms dry crusts, which result in the bronchi occlusion and lead to frequent and severe bronchospasm as well as atelectasis. The lethal outcomes are observed as the result of the development of the diffusive process in the respiratory tract.

The bronchitis joining is usually observed on the 4-5th day of the disease, in such cases one can hear dry rale over the lungs. Paragrippal pneumonia often develops in the viral affection of the lower respiratory tract. They have an acute development accompanied by a high temperature, expressed cyanosis, shortness of breath and absence of distinct changes in the percussion sound, scanty

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auscultation data. They usually take a non-malignant course. The joining of the secondary bacterial flora considerably worsens the course of the disease: the intoxication intensifies, the shortness of breath and cyanosis become more expressed, the cough with sputum discharge becomes more frequent. The percussion reveals the shorting of the percussion sound, a lot of moist rale can be heard at the same areas.

Complications

Paragrippe can be complicated by tonsilitis, sinusitis, otitis, eustachiitis and can cause the worsening of the chronic unspecitic diseases of the lungs. Along with the affection of the respiratory tract there are some changes of the nervous system in many paragrippal patients, even in case of the mild course of the disease. They are mainly some slightly expressed symptoms of the functional malaise, headache, dizziness, aches all over the body etc. However, during the clinical examination serouse meningitis with the posterior nuchae muscles rigidity and symptoms of Kernig and Brudzinsky was diagnosed in some patients. The cerebrospinal fluid flew out under the increased pressure, lymphocyte pleocytosis oscillated in a wide range from 70 to 850 and higher in that case. The paragrippal virus type 3 was most often found in the fluid. The normalization of the cerebrospinal fluid and fading of the meningeal symptoms were not always parallel with the catarrhal changes in the mucous membrane of the respiratory tract.

The reinfection with the paragrippal viruses,especially type 3,was registered several times in adults and in children. The frequency of the reinfection remains still unknown, it is possible that many patients are reinfected more than once. The results of the observation in the series of the consequent outbursts of the type 3 infection showed that 17 % of the children infected during the first outburst were reinfected during the following outbursts, although the interval between the outbursts did not exceed 9 months. The disease develops more rarely in case of the reinfection and its course is much easier as compared with that of the primary infection.

Diagnosis

The laboratory confirmation of the disease etiology is an important stage in the examination of the patient. The main method used under the conditions of the practical laboratories is an immunofluorescent test that is used for the discovery of virus antigens in the epithelial cells of the upper respiratory tract. This method provides a fast deciphering of the disease etiology.

Among the other express methods of diagnosis of the respiratory diseases an immunoferment test on the solid phase has become widely spread, it is used for the serological diagnostics. The radioimmunoassay and chain polymerize reaction are also used.

Another direction in the serological diagnostics is the investigation of single serum samples, it is aimed at the determination of IgM because it constitutes the

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basis of the primary immune response. A test of immunosorbent hemadsorption has been devised for this purpose. The laboratory diagnostics of the paragrippal infection based on the isolation of viruses in the sensitive cell cultures has not lost its importance.

Differential diagnosis

During the first days of the disease the clinical diagnosis is often difficult, as some symptoms are similar to influenza. In such cases it is important to thoroughly study the onset of the disease. Influenza is characterized by a sudden onset and temperature increase up to 38 °Ñ and higher and always more or less expressed chill, and the catarrhal component absence. In paragrippe the temperature increases gradually and there is a cough with sputum discharge from the first days. Croup in paragrippe is often clinically manifested by the symptoms of acute laryngitis, which is sometimes limited by the affection of the infraglottica area of the larynx only, and the severity of the patient's condition depends on the severity of stenosis, the intoxication manifestations are less expressed. In influenza, especially, in the severe cases, there are symptoms of laryngotracheobronchitis and the severity depends on the intoxication degree.

Treatment

In mild and moderate cases bed regimen is recommended till the temperature decreases. The dairy and vegetable diet, abundant drink (tea, cranberry juice, alkali mineral water) are prescribed. Both adults and children are prescribed symptomatic treatment (syrup, paracetamol, mucaltinum, inf. althaeae - to delute sputum, pertussin, broncholytin, bromhexin - in case of the increased cough reflex and others).

In severe cases the following medicines are prescribed: immunoglobulin (hyperimmune and normal), monoclone antibodies, interferon, ribamidil, bonaphtonum, alpisarinum. The antibacterial medicines are prescribed in case of complications with the bacterial flora. The hot foot baths, steam inhalations, corticosteroids are the most effective in larynx stenosis.

Prophylaxis

The specific prophylaxis of the paragrippal infection has not been worked out so far. The non-specific prophylaxis is similar to the one in other acute respiratory virus diseases.

Date: 2014-12-21; view: 2127