Adenovirus infection is an acute viral infectious process accompanied by damage to the respiratory tract, eyes, lymphoid tissue, and digestive tract. Signs of adenovirus infection are moderate intoxication, fever, rhinorrhea, hoarseness of voice, cough, conjunctival hyperemia, mucous discharge from the eyes, intestinal dysfunction. In addition to clinical manifestations, serological and virological research methods are used when making a diagnosis. Therapy of adenovirus infection is carried out with antiviral drugs (orally and topically), immunomodulators and immunostimulants, symptomatic agents.
B34.0 Adenovirus infection of unspecified localization
Adenovirus infection is a disease from the group of acute respiratory viral infections caused by adenovirus and characterized by the development of rhinopharyngitis, laryngotracheobronchitis, conjunctivitis, lymphadenopathy, dyspeptic syndrome. In the general structure of acute respiratory diseases, adenovirus infection accounts for about 20%.
The greatest susceptibility to adenoviruses is demonstrated by children from 6 months to 3 years old. It is believed that at preschool age, almost all children suffer one or more episodes of adenovirus infection. Sporadic cases of adenovirus infection are recorded year-round; in the cold season, the incidence is in the nature of epidemic outbreaks. Close attention to adenovirus infection is focused on infectious diseases, pediatrics, otolaryngology, ophthalmology.
Currently, there are more than 30 serovars of viruses of the Adenoviridae family that cause human disease. The most common cause of outbreaks of adenovirus infection in adults are 3, 4, 7, 14 and 21 serotypes. Serovars of types 1, 2, 5, 6 usually affect preschool children. The causative agents of pharyngoconjunctival fever and adenovirus conjunctivitis in most cases are serotypes 3, 4, 7.
The virions of the pathogen contain double-stranded DNA, have a diameter of 70-90 nm and three antigens (group-specific A-antigen; determining the toxic properties of adenovirus B-antigen and type-specific C-antigen). Adenoviruses are relatively stable in the external environment: under normal conditions they persist for 2 weeks, tolerate low temperatures and drying well. At the same time, the causative agent of adenovirus infection is inactivated when exposed to ultraviolet rays and chlorine-containing disinfectants.
Adenoviruses are spread from sick people who secrete the pathogen with nasopharyngeal mucus and feces. Hence, there are 2 main ways of infection – in the early period of the disease – airborne; in the late period – fecal-oral – in this case, the disease proceeds according to the type of intestinal infections. A waterway of infection is possible, so adenovirus infection is often called “swimming pool disease”.
The source of adenovirus infection can also be virus carriers, patients with asymptomatic and erased forms of the disease. Immunity after an infection is type-specific, therefore, repeated diseases caused by another serotype of the virus are possible. Nosocomial infection occurs, including during parenteral treatment procedures.
Adenovirus can enter the body through the mucous membranes of the upper respiratory tract, intestines or conjunctiva. Reproduction of the virus takes place in epithelial cells, regional lymph nodes and lymphoid formations of the intestine, which coincides with the incubation period of adenovirus infection. After the death of the affected cells, viral particles are released and penetrate into the blood, causing viremia.
Changes develop in the nasal membrane, tonsils, posterior pharyngeal wall, conjunctiva; inflammation is accompanied by a pronounced exudative component, which causes the appearance of serous discharge from the nasal cavity and conjunctiva. Viremia can lead to involvement in the pathological process of the bronchi, digestive tract, kidneys, liver, spleen.
The main clinical syndromes, the form of which this infection can take, are catarrh of the respiratory tract (rhinopharyngitis, tonsillopharyngitis, laryngotracheobronchitis), pharyngoconjunctival fever, acute conjunctivitis and keratoconjunctivitis, diarrheal syndrome. The course of adenovirus infection can be mild, moderate and severe; uncomplicated and complicated.
The incubation period for adenovirus infection lasts 2-12 days (more often 5-7 days), followed by a manifest period with the consistent appearance of symptoms. Early signs are an increase in body temperature to 38-39 ° C and moderate symptoms of intoxication (lethargy, decreased appetite, muscle and joint pain).
Respiratory tract damage
Catarrhal changes in the upper respiratory tract occur simultaneously with fever. Serous discharge from the nose appears, which then becomes mucopurulent; nasal breathing becomes difficult. There is moderate hyperemia and swelling of the mucous membrane of the posterior pharyngeal wall, a spot whitish plaque on the tonsils. With adenovirus infection, a reaction occurs from the submandibular and cervical lymph nodes. In the case of laryngotracheobronchitis, hoarseness of voice appears, dry barking cough, shortness of breath is possible, the development of laryngospasm.
Conjunctival lesion in adenovirus infection can occur by the type of catarrhal, follicular or filmy conjunctivitis. Usually, the eyes are involved in the pathological process alternately. It bothers the pain, burning, lacrimation, the feeling of the presence of a foreign body in the eye. Examination reveals moderate redness and swelling of the eyelid skin, hyperemia and granularity of the conjunctiva, injection of the sclera, sometimes the presence of a dense grayish-white film on the conjunctiva. In the second week of the disease, signs of keratitis may join conjunctivitis.
If an adenovirus infection occurs in the intestinal form, there are paroxysmal pains in the umbilical and right iliac region, fever, diarrhea, vomiting, mesenteric lymphadenitis. With severe pain syndrome, the clinic resembles acute appendicitis. Fever with adenovirus infection lasts 1-2 weeks and can be wave-like. Signs of rhinitis and conjunctivitis subside after 7-14 days, catarrh of the upper respiratory tract – after 14-21 days.
In severe form of the disease, parenchymal organs are affected; meningoencephalitis may occur. Children of the first year of life often develop adenovirus pneumonia and severe respiratory failure. The complicated course of adenovirus infection is usually associated with the layering of secondary infection; the most common complications of the disease are sinusitis, otitis media, bacterial pneumonia.
Recognition of adenovirus infection is usually performed on the basis of clinical data: fever, catarrh of the respiratory tract, conjunctivitis, polyadenitis, consistent development of symptoms. The methods of rapid diagnosis are the reaction of immunofluorescence and immune electron microscopy. Retrospective confirmation of the etiological diagnosis is carried out by the methods of ELISA, RTGA, RSC. Virological diagnostics involves the isolation of adenovirus from nasopharyngeal flushes, scraping from the conjunctiva and feces of the patient, however, due to the complexity and duration, it is rarely used in clinical practice.
Differential diagnosis of various clinical forms is carried out with influenza, other acute respiratory infections, pharyngeal and eye diphtheria, infectious mononucleosis, mycoplasma infection, yersiniosis. For this purpose, as well as for the appointment of local etiotropic treatment, patients need to consult an ophthalmologist and an otolaryngologist.
Adenovirus infection treatment
General etiotropic therapy is carried out with antiviral drugs (umifenovir, ribavirin, a drug made of antibodies to human gamma interferon). Local therapy includes: instillation of eye drops (solution of deoxyribonuclease or sodium sulfacil), application of acyclovir in the form of eye ointment for the eyelid, intranasal application of oxaline ointment, endonasal and endopharyngeal instillation of interferon. Symptomatic and post-syndrome therapy is carried out: inhalation, taking antipyretic, antitussive and expectorant drugs, vitamins. In case of adenovirus infection, burdened with bacterial complications, antibiotics are prescribed.
Prognosis and prevention
Uncomplicated forms end favorably. Deaths may occur in young children due to the occurrence of severe bacterial complications. Prevention is similar to the prevention of other acute respiratory infections. During periods of epidemic outbreaks, isolation of patients is indicated; ongoing disinfection, ventilation and UVI of premises; administration of interferon to persons at risk of infection. A specific vaccination against adenovirus infection has not yet been developed.