Adenovirus infection
The content of the article:
- Causes and risk factors
- Forms of the disease
- Symptoms of adenovirus infection
- Diagnostics
- Treatment of adenovirus infection
- Potential consequences and complications
- Forecast
- Prevention
Adenovirus infection causes a whole group of acute infectious diseases occurring with moderate intoxication syndrome and damage to the mucous membranes of the upper respiratory tract, lymphoid tissue, eyes or intestines.
Structure of adenovirus
Adenoviruses were first isolated in 1953 from children with atypical pneumonia and acute respiratory viral infection, occurring with the phenomena of conjunctivitis by W. Rowe. Subsequently, numerous studies on animals have shown the oncogenicity of adenoviruses, that is, their ability to provoke the development of malignant tumors.
Adenovirus infection is widespread. In the general structure of the incidence of viral infectious diseases, it accounts for 5-10%. The incidence of adenovirus infections is recorded everywhere and all year round, with a peak in the cold season. The disease can occur both in the form of epidemic outbreaks and in the form of sporadic cases.
Epidemic outbreaks of adenovirus infection are most often caused by viruses belonging to types 14 and 21. Adenoviral hemorrhagic conjunctivitis is caused by type 3, 4, or 7 viruses.
Such manifestations of adenovirus infection as hemorrhagic cystitis and meningoencephalitis are extremely rare.
Adenovirus infection more often affects children and young people. In most cases, the duration of the disease is 7-10 days, but sometimes it can take a relapsing course and last up to several weeks.
Causes and risk factors
The causative agents of adenovirus infection are DNA viruses belonging to the genus Mastadenovirus of the Adenoviridae family. Currently, experts have described over 100 serological types of adenoviruses, about 40 of them were isolated from humans.
All serovars of adenoviruses differ significantly in their epidemiological characteristics. For example, viruses of types 1, 2 and 5 can cause damage to the upper respiratory tract in young children, in which the persistence of the virus in the lymphoid tissue persists for a long time. Viruses 4, 7, 14 or 21 are responsible for the development of upper respiratory tract inflammation in adults.
Adenovirus type 3 is the causative agent of pharyngoconjunctival fever (adenoviral conjunctivitis) in adults and children of the older age group.
In the external environment, adenoviruses are quite stable. At room temperature, they remain viable for 15 days. Chlorine disinfectants and UV rays kill them in minutes. Adenoviruses tolerate low temperatures well. For example, in water at a temperature of 4 ° C, they retain their viability for over two years.
The source and reservoir of infection is a sick person or a virus carrier. After the illness, the virus is excreted with the secretion of the upper respiratory tract for another 25 days, and with feces - over 45 days.
The mechanism of transmission of adenovirus infection in children and adults is most often aerosol (suspension in the air of droplets of mucus, saliva), but alimentary (fecal-oral) can also be observed. Transmission of infection through contaminated environmental objects is very rare.
The route of transmission of adenovirus infection is mainly airborne
The susceptibility of people to adenovirus infection is high. After the transferred disease, persistent immunity remains, but it is type-specific and therefore repeated cases of the disease may occur due to another serovar of the virus.
With the aerosol route of infection, the adenovirus enters the mucous membrane of the upper respiratory tract, and then migrates through the bronchi to the lower section. The entrance gate can also be the mucous membrane of the eyes or the intestines, into which the virus enters together with the sputum particles at the time of their ingestion.
Further multiplication of the infectious agent occurs in the epithelial cells of the respiratory tract and small intestine. In the lesion focus, inflammation begins, accompanied by hyperplasia and infiltration of the submucosal tissue, expansion of its capillaries, and hemorrhages. Clinically, this is manifested by pharyngitis, sore throat, diarrhea or conjunctivitis (often of a membranous nature). In severe cases, adenovirus infection can lead to the development of keratoconjunctivitis, accompanied by persistent clouding of the cornea and blurred vision.
From the primary focus of inflammation with the lymph flow, the virus enters the regional lymph nodes, causing hyperplasia of the lymphoid tissue. As a result, the patient develops mesenteric adenitis and lymphadenopathy.
An increase in tissue permeability and inhibition of macrophage activity leads to the development of viremia and the introduction of adenoviruses into various organs, which is accompanied by the development of intoxication syndrome.
Adenoviruses are fixed by macrophages in liver and spleen cells. This process is clinically manifested by the formation of hepatolienal syndrome (an increase in the liver and spleen occurs).
Forms of the disease
According to their ability to cause agglutination (adhesion) of erythrocytes, adenoviruses are divided into 4 subgroups (I – IV).
According to the predominance of certain symptoms or their combination in the clinical picture, the following forms of adenovirus infection in adults and children are distinguished:
- acute respiratory viral infection (ARVI);
- rhinopharyngitis;
- rhinopharyngotonsillitis;
- rhinopharyngobronchitis;
- pharyngoconjunctival fever;
- conjunctivitis;
- keratoconjunctivitis;
- pneumonia.
Signs of adenoviral conjunctivitis
Symptoms of adenovirus infection
The incubation period for adenovirus infection lasts from 24 hours to 15 days, but most often its duration is 5-8 days. The disease begins acutely. The patient develops moderately pronounced symptoms of intoxication:
- decreased appetite;
- adynamia;
- general weakness;
- muscle and joint pain;
- mild headache;
- slight chills.
On days 2-3 from the onset of the disease, the body temperature rises to subfebrile values (up to 38 ° C) and lasts for 5-8 days. Only occasionally can the body temperature rise to 39 ° C.
With adenovirus infection, the body temperature rises to 38 ° C and lasts about a week
In rare cases, symptoms of adenovirus infection may include frequent loose stools and abdominal pain (more common in children).
Along with the symptoms of intoxication, there are signs of inflammation of the upper respiratory tract. Patients complain of nasal congestion with profuse discharge, initially serous, and then serous-purulent. There is a sore throat, dry cough. A few days later, they are joined by profuse lacrimation, pain in the eyes.
When examining patients, attention is paid to hyperemia (redness) of the face, injection of the sclera. In some cases, a papular rash appears on the skin.
With adenovirus infection, conjunctivitis often develops, accompanied by mucous discharge. In young children, swelling of the eyelids rapidly increases, and membranous formations appear on the mucous membrane. With untimely treatment, the inflammatory process can spread to the cornea, leading to the formation of infiltrates. Conjunctivitis with adenovirus infection is unilateral at first, and then becomes bilateral. After recovery, the resorption of corneal infiltrates occurs slowly, the process can continue for 1-2 months.
Conjunctivitis is common with adenovirus infection
In many cases, adenoviral conjunctivitis is associated with pharyngitis. This form of the disease is called pharyngoconjunctival fever. On examination of the oral cavity, slight redness of the posterior pharyngeal wall and soft palate is noted. The pharyngeal tonsils are slightly hypertrophied and loosened. In some cases, a whitish bloom is located on their surface, which can be easily removed with a cotton swab. Submandibular, and sometimes cervical and even axillary lymph nodes increase in size and become painful on palpation.
With the descending nature of the inflammatory process, laryngitis, bronchitis or pneumonia develops. Laryngitis against the background of adenovirus infection is relatively rare and most often in children in the first years of life. It is characterized by hoarseness, sore throat, “barking” (loud and sharp) cough.
With the development of bronchitis, the cough becomes persistent. During auscultation, hard breathing is heard in the lungs, as well as dry wheezing in different parts.
The most serious manifestation of adenovirus infection in children and adults is adenoviral pneumonia. Usually it occurs on 3-5 days of illness, only in children of the first years of life, an adenovirus infection can immediately manifest as an inflammatory process in the lung tissue. The symptoms of adenovirus pneumonia are:
- growing general weakness;
- cough;
- dyspnea;
- cyanosis of the nasolabial triangle;
- excessive sweating.
Adenovirus pneumonia can be both small-focal and confluent, that is, it can simultaneously cover several segments of the lungs.
Adenovirus pneumonia is a dangerous complication of adenovirus infection - on X-ray
In children of the first three years of life, adenoviral pneumonia often takes a severe course and is accompanied by the appearance of maculopapular skin rash, the formation of foci of necrosis in the skin, brain and lungs.
Damage to the cardiovascular system with adenovirus infection is extremely rare and only in severe infectious and inflammatory process. Their characteristic features are a systolic murmur at the apex of the heart and muffling of its tones.
Inflammation of the respiratory tract with adenovirus infection in children (much less often in adults) is often combined with damage to the gastrointestinal tract. Patients develop abdominal pain, diarrhea, enlargement of the spleen and liver.
Diagnostics
Adenovirus infection requires differential diagnosis with a number of other pathologies:
- pneumonia;
- tuberculosis;
- diphtheria;
- conjunctivitis and keratitis of a different (not adenoviral) etiology;
- acute respiratory infections of other etiology, including influenza.
The main diagnostic criteria for adenovirus infection are:
- moderate intoxication;
- signs of respiratory tract damage;
- conjunctivitis;
- lymphadenopathy (regional or widespread);
- exanthema;
- hepatolienal syndrome;
- dysfunction of the digestive system.
In the general analysis of blood with adenovirus infection, no significant changes are noted, except for a slight increase in ESR.
Virological studies of discharge from the nasopharynx and eyes, which allow obtaining a culture of the virus in clinical practice, are not used due to the high complexity and cost, as well as the duration of the study.
Bacterial culture from the nasopharynx allows you to determine the culture of the virus, but this is a complex and expensive analysis
For the retrospective diagnosis of adenovirus infection, type-specific RN and RTGA and group-specific CSCs are performed - reactions with paired sera obtained on the first day of the disease and during the period of subsidence of clinical manifestations. An increase in the titer of serum antibodies by at least four times confirms the presence of adenovirus infection.
For approximate diagnosis of adenovirus infection, the method of immune electron microscopy and RIF can be used.
Treatment of adenovirus infection
With an uncomplicated course of diseases caused by adenovirus infection, the patient is prescribed bed rest and an abundant drink is recommended. When signs of conjunctivitis appear, instillation of eye drops with antiviral effect is indicated. To normalize body temperature, relieve headaches and muscle pains, nonsteroidal anti-inflammatory drugs are prescribed. In some cases, the use of vitamin preparations and antihistamines is justified.
In the case of an uncomplicated course of adenovirus infection, bed rest and plenty of drink are sufficient for treatment
In case of complicated adenovirus infection and the addition of a secondary bacterial infection to it, detoxification therapy is performed (intravenous administration of glucose and saline solutions, ascorbic acid), and broad-spectrum antibiotics are also prescribed. In severe cases of adenovirus infection, treatment is carried out in a hospital setting.
For prophylactic purposes, antibiotics for adenovirus infection are used only in elderly people suffering from chronic bronchopulmonary diseases, as well as in patients with manifestations of immunosuppression.
Potential consequences and complications
The most common complications of adenovirus infection are:
- sinusitis;
- otitis;
- obstruction of the Eustachian tube, resulting from a prolonged increase in lymphoid tissue in the pharynx;
- false croup (laryngospasm);
- bacterial pneumonia;
- pyelonephritis.
Forecast
The outlook is generally favorable. In most cases, the disease ends with full recovery within 7-10 days.
Prevention
Some countries are vaccinated with a live attenuated virus vaccine to prevent adenovirus infection in adults. But in most countries, including Russia, immunoprophylaxis is not carried out, since there is an opinion about the ability of adenoviruses to lead to malignant cells in the human body. For the prevention of adenovirus infections, it is important to observe sanitary and hygienic rules, to control the regularity and correct chlorination of water in swimming pools.
Children of the first years of life and at risk of contracting an adenovirus infection (contact with a sick person) are shown the introduction of leukocyte interferon and specific immunoglobulin.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
