Adenovirus infection

Adenovirus infection is a group of anthroponotic acute viral diseases with damage to the mucous membranes of the respiratory tract, eyes, intestines and lymphoid tissue, mainly in children and young people.

The term "adenovirus" was proposed by Enders and Francis in 1956, and diseases caused by this pathogen began to be called adenoviral.

ICD-10 codes

• B34.0. Adenovirus infection, unspecified.
• B30.0. Keratoconjunctivitis due to adenovirus.
• B30.1 Conjunctivitis due to adenovirus.

[ 1 ], [ 2 ]

Epidemiology of adenovirus infection

The source of infection is a sick person who releases the virus into the environment throughout the illness, as well as a virus carrier. Viruses are released from the upper respiratory tract, with feces, tears. The role of "healthy" virus carriers in the transmission of infection is quite significant. The maximum period of virus release is 40-50 days. Adenoviral conjunctivitis can be a nosocomial infection. The mechanism of transmission is airborne, feco-oral. The routes of transmission are airborne, food, contact-household. Intrauterine infection of the fetus is possible. Susceptibility is high. Mostly children and young people get sick. Seasonality is not decisive, but in the cold season, the incidence of adenoviral infections increases, with the exception of pharyngoconjunctival fever, which is diagnosed in the summer. The nature of the epidemic process is largely determined by the serological types of adenoviruses. Epidemics caused by adenoviruses types 1, 2, 5 are rare; types 3 and 7 are more common. After the disease, species-specific immunity is formed.

[ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ]

What causes adenovirus infection?

The causative agents are adenoviruses of the genus Mastadenovirus (mammalian adenoviruses) of the Adenoviridae family. The genus includes 80 species (serotypes).

The family includes viruses with a naked capsid, the average diameter of the virion is 60-90 nm. The mature virus consists of 252 capsomeres, including 240 hexons that form edges, and 12 pentons. forming verticals. The genome is represented by a linear double-stranded DNA. Each virion has at least 7 antigenic determinants. Antigenic properties form the basis for the classification of adenoviruses. The nucleocapsid is a single complement-binding antigen of this family. That is why adenoviruses are detected in the complement-binding serum using group-specific serum. Hexons contain reactive determinants of the family and type-specific antigens that act upon the release of hexons from the virion and are responsible for the manifestation of the toxic effect. Hexon antigens also contain genus- and group-specific determinants. Pentons contain small virus antigens and a reactive soluble antigen of the family found in infected cells. Purified DNA strands contain the major type-specific antigen. Pentons and strands determine the hemagglutinating properties of viruses. Surface antigens of structural proteins are species- and type-specific. The genome is represented by a linear double-stranded DNA molecule.

Adenoviruses are extremely stable in the environment. They survive in a frozen state and adapt to temperatures from 4 to 50 °C. In water at 4 °C, they remain viable for 2 years; on glass and clothing, they survive for 10-45 days. They are resistant to ether and other lipid solvents. They die from exposure to ultraviolet radiation and chlorine; at a temperature of 56 °C, they die after 30 minutes.

For humans, 49 types of adenoviruses are pathogenic, the most significant are serovars of types 1, 2, 3, 4, 5, 6, 7, 8, 12, 14, 21, and types 1, 2, 5, 6 most often cause diseases in preschool children; types 3, 4, 7, 14, 21 - in adults.

Pathogenesis of adenovirus infection

Various organs and tissues are involved in the pathological process: respiratory tract, lymphoid tissue, intestines, bladder, eyes, brain. Adenoviruses of serotypes 3, 4, 8, 19 cause conjunctivitis, and serotypes 40, 41 cause gastroenteritis. Infections caused by serotypes 3, 7, 11, 14. 21 are acute with rapid elimination of the pathogen. Serotypes 1, 2, 5, 6 cause mild diseases, but can persist for a long time in the lymphoid tissue of the tonsils, adenoids, mesenteric lymph nodes, etc. Adenoviruses can penetrate the placenta, causing fetal developmental abnormalities, pneumonia in newborns. The entry point for infection is the upper respiratory tract or the mucous membrane of the conjunctiva.

Primary replication of the virus occurs in the epithelial cells of the mucous membrane of the respiratory tract and intestines, in the conjunctiva of the eyes and lymphoid tissue (tonsils, mesenteric lymph nodes). Adenoviruses, circulating in the blood, affect the vascular endothelium. Intranuclear inclusions of an oval or round shape containing DNA are formed in the affected cells. The cells increase in size, undergo destruction, and serous fluid accumulates under the epithelium. This leads to exudative inflammation of the mucous membranes, the formation of fibrinous films and necrosis. Lymphoid infiltration of the deep layers of the walls of the trachea and bronchi is observed. The lumen of the bronchi contains serous exudate with an admixture of macrophages and single leukocytes.

In young children, viruses can reach the alveoli via the bronchogenic route, causing pneumonia. In addition to local changes, adenoviruses have a general toxic effect on the body, which is expressed by symptoms of intoxication.

[ 10 ], [ 11 ], [ 12 ]

Symptoms of adenovirus infection

The incubation period lasts from 5 to 14 days.

Adenovirus infection is characterized by polymorphism of clinical symptoms and syndromes. The clinical picture may be dominated by symptoms indicating damage to the respiratory tract, eyes, intestines, bladder, and lymphoid tissue. Meningoencephalitis may develop. In adults, adenovirus infection often occurs in a latent form, while in young people it is clinically expressed. The disease develops gradually. The temperature rises from the first day of the disease, its duration varies from 5-7 days to 2 weeks. Sometimes subfebrile temperature persists for up to 4-6 weeks, there may be a two-wave fever, and three waves are rarely observed. In most cases, the symptoms of intoxication are moderate even with high fever.

Due to the tropism of adenoviruses to lymphoid tissue, the nasopharyngeal tonsils are involved in the process from the first days of the disease and difficulty breathing through the nose, puffiness of the face, serous rhinitis with copious discharge (especially in younger age groups) appear. A characteristic sign of the disease is pharyngitis with a pronounced exudative component. Pharyngitis is characterized by moderate pain or sore throat. During examination, hyperplasia of lymphoid follicles is revealed against the background of edematous and hyperemic mucous membrane of the posterior pharyngeal wall. The tonsils are enlarged, in some patients white delicate plaques are visible, which can be easily removed with a spatula.

In adults, unlike children, clinical signs of bronchitis are rarely detected. Children are characterized by a moderate short-term cough with scanty mucous discharge. In addition, almost every fifth sick child develops acute stenosing laryngotracheitis, which is severe, with a pronounced exudative component. Some children develop obstructive syndrome, which has an edematous or mixed form. It can persist for up to 3 weeks. In this case, the cough is wet, obsessive; exhalation is difficult, dyspnea is of a mixed type. Auscultation reveals a large number of wet, different-sized and single dry wheezes. In young children, obliterating bronchitis may develop.

Adenovirus infection is often accompanied by moderate lymphadenopathy. Cervical, submandibular, mediastinal and mesenteric lymph nodes enlarge. Mesadenitis manifests itself either against the background of other manifestations of adenovirus infection or as the main syndrome. The main clinical symptom is acute paroxysmal pain mainly in the lower abdomen (in the right iliac, periumbilical regions). Nausea often appears, less often vomiting, diarrhea. Changes in the cardiovascular system are practically absent. Some patients have hepatosplenic syndrome, sometimes with increased activity of aminotransferases (ALT, AST).

Conjunctivitis often develops. At first it is unilateral, later the second eye is affected. Catarrhal, follicular and membranous conjunctivitis are distinguished. The last form is the most typical. The conjunctiva of the eyelids is hyperemic, granular, slightly swollen; a small secretion is possible. After 1-3 days, white or grayish-white membranous plaques appear on the conjunctiva. A common symptom is eyelid edema. Less common is keratoconjunctivitis, in which an infiltrate forms in the subepithelial layer of the cornea, its opacity occurs, and visual acuity decreases. The process lasts up to one month and is usually reversible.

In adults, adenovirus infection may have clinical signs of cystitis. Cases of acute encephalitis, most often caused by serotype 7 of adenoviruses, have been described. Pharyngoconjunctival fever, which has a fairly clear clinical picture, with high 4-7-day fever, intoxication, nasopharyngitis, and membranous conjunctivitis, is an independent form of the disease.

[ 13 ]

Complications of adenovirus infection

Frequent complications are otitis, sinusitis and pneumonia, developing as a result of secondary infection. Often, chronic tonsillitis worsens against the background of adenovirus infection. Cases of complications of adenovirus mesadenitis with intestinal intussusception have been described.

[ 14 ], [ 15 ], [ 16 ], [ 17 ]

Diagnosis of adenovirus infection

Clinically, adenovirus infection is diagnosed by the presence of conjunctivitis, pharyngitis, and lymphadenopathy against the background of fever.

The blood picture in adenovirus infection is non-specific and has no diagnostic value. Serological diagnostics is used for retrospective decoding of the etiology of ARVI. RTGA and RSK are widely used. Express diagnostic methods are represented by the indirect hemadsorption reaction, ELISA and RIF. They allow detecting adenovirus antigens in the epithelial cells of the nasal cavity within 3-4 hours. Cell scraping is performed in the first days of the infectious process. Detection of viral antigens in the nuclei of epithelial cells indicates a latent course of the infectious process, the presence of antigens in the cytoplasm allows diagnosing an acute disease. Isolation of the virus in tissue culture is used for scientific purposes.

[ 18 ], [ 19 ], [ 20 ], [ 21 ]

Differential diagnostics

Differential diagnostics are carried out with ARVI of other etiology, diphtheria of the oropharynx, diphtheria of the eye, tonsillitis. Adenovirus infection has a number of similar symptoms with infectious mononucleosis, typhoid fever. Yersiniosis also occurs with pharyngitis, conjunctivitis, hepatosplenic syndrome, diarrhea and prolonged fever.

[ 22 ], [ 23 ], [ 24 ], [ 25 ]

Indications for consultation with other specialists

An indication for a surgeon's consultation is the development of adenoviral mesadenitis, which occurs with severe abdominal pain and vomiting. An ophthalmologist's consultation is indicated in case of eye damage.

[ 26 ], [ 27 ], [ 28 ], [ 29 ]

Indications for hospitalization

Most patients are treated at home. Patients with severe forms of the disease, complications, concomitant diseases, and epidemiological indications are subject to hospitalization.

[ 30 ], [ 31 ], [ 32 ], [ 33 ], [ 34 ]

Treatment of adenovirus infection

Regime and diet

During the febrile period, bed rest is indicated. No special diet is required.

[ 35 ], [ 36 ], [ 37 ], [ 38 ]

Drug treatment

In most cases, etiotropic therapy is not prescribed for uncomplicated adenovirus infection. In severe cases of infection, arbidol, interferon preparations and their inducers may be prescribed. Among the human leukocyte interferon preparations, the following are used: dry human leukocyte interferon 2 times a day in both nasal passages, 5 drops (0.25 l), interlock 1 drop 10 times a day in each eye (for the treatment of conjunctivitis), dry leukinferon for injection (administered intramuscularly, by inhalation) 100 thousand IU. Antibiotics are indicated when a secondary bacterial infection occurs.

[ 39 ], [ 40 ], [ 41 ], [ 42 ]

Clinical examination

Outpatient monitoring is not carried out.

[ 43 ], [ 44 ], [ 45 ], [ 46 ], [ 47 ], [ 48 ]

How is adenovirus infection prevented?

In the prevention of adenoviral diseases, the main role belongs to methods of increasing the non-specific resistance of the body (hardening, rational nutrition). During epidemic outbreaks, contact persons are prescribed interferon or drugs from the group of interferon inducers. Current disinfection is carried out in the outbreak. During outbreaks of adenoviral infections, children are separated for at least 10 days after the last patient is identified.

[ 49 ], [ 50 ], [ 51 ], [ 52 ]

What is the prognosis for adenovirus infection?

The prognosis is usually favorable. Discharge from the hospital occurs after clinical recovery.