Adenovirus infection
Introduction
Introduction to adenovirus infection Can cause infections of people, baboons, horses, pigs, sheep, dogs, etc. The experiment found that it can cause carcinogenesis in animals; it has not been proven to cause human tumors, but it can cause a variety of infectious diseases in humans. basic knowledge The proportion of the disease: the probability of the population is 2.3% Susceptible people: no specific population Mode of infection: respiratory communication exposure Complications: pneumonia, bronchitis
Cause
Adenovirus infection etiology
(1) Causes of the disease
At present, there are 6 subtypes (A to F) and 47 different serotypes of adenovirus (according to the neutralization test). It is known that about 20 subtypes can infect humans, and the virus is 20 to 80 nm in diameter. The capsid capsid contains double-stranded DNA, which is unstable to heat and acid. Because it does not contain lipids, it has strong resistance to lipid-dissolving agents such as bile salts, so it can survive in the intestine. Different subtypes can cause different infections.
(two) pathogenesis
When the respiratory virus invades the ciliated epithelial cells on the surface of human respiratory tract, it replicates and spreads in it and directly causes damage to the infected cells, causing local lesions or systemic toxic symptoms. The tissue damage caused by some viruses may be caused by the body's immune response. Mediated, such as respiratory syncytial virus, the direct damage to the airway epithelial cells of the respiratory tract is the lightest, but can cause serious respiratory diseases in infants and young children; the most prone to age is the highest level of maternal antibody; the natural infection after vaccination The severity of the disease suggests that the pathogenesis may be related to the immune response. The pathological changes of respiratory virus infection include nasal, pharyngeal, laryngeal mucosal congestion, edema, exudation and monocyte infiltration, and some cells may undergo degeneration, necrosis, and shedding. Inclusion bodies can be found in the cytoplasm or nucleus of epithelial cells. The degree of lesions is related to the type, type and location of the virus. After a few days, the epithelial cells can regenerate and return to normal. If the lesion involves the bronchioles, epithelial cell necrosis can occur. , exfoliation, extensive bronchial wall infiltration of mononuclear cells, fibrin, cell debris and viscous mucus Can block the lumen and cause atelectasis, emphysema, viral pneumonia initially showed a progressive reduction of cilia, epithelial vacuolization, epithelial cell degeneration, alveolar necrosis, collapse, necrosis of alveolar wall And thickening, interstitial edema and monocytes, lymphocyte infiltration, and bacterial infection, mucosal congestion, neutrophil infiltration and mucopurulent secretions can be seen, severe cases can occur lung abscess, sepsis and multiple organs Suppurative changes.
Prevention
Adenovirus infection prevention
1. Vaccines in use and trial use are formaldehyde inactivated vaccines and live attenuated vaccines. However, due to the carcinogenic effect of adenovirus on newborn hamsters, people have doubts about the role of vaccines. Recently, an adenovirus capsid subunit vaccine has been developed to solve the safety problem of vaccines.
2. It is reported that the capsid component of useful DNA is a vaccine or an oral vaccine (type 4 and type 7 adenovirus).
The live attenuated vaccine and the inactivated vaccine are effective, and the adenovirus is carcinogenic, and combined with the monkey virus SV40 can produce a more carcinogenic hybrid virus, so it is difficult to promote the application. The capsid component of the useful DNA is reported as a vaccine. Or oral vaccine (type 4 and type 7 adenovirus) is effective.
Complication
Adenovirus infection complications Complications pneumonia bronchitis
Patients with complicated bronchitis and pneumonia immunodeficiency may be infected by central nervous system such as encephalitis.
Symptom
Adenovirus infection symptoms Common symptoms Sore throat Urinary urgency Acute hematuria
The incubation period is 4 to 5 days.
1. The most common clinical manifestations in children
(1) Respiratory tract infections: Rhinitis is the most common symptom of infant adenovirus infection. This age group can occasionally cause fulminant bronchitis and pneumonia, and some children develop pertussis syndrome.
(2) pharyngo-conjunctival fever (APC fever): adenovirus type 3,7 caused by more, summer can occur a small epidemic, related to swimming pool water, acute onset, fever above 38 °C, pharyngitis, rhinitis , conjunctivitis and cervical lymphadenitis, spherical conjunctiva and sacral conjunctiva can be seen granules, redness, often unilateral, bilateral are often one side heavier, symptoms last 1 to 2 weeks, no sequelae, generally without bronchus Inflammation and pneumonia.
(3) hemorrhagic cystitis (hemorrhagic cystitis): mostly caused by adenovirus type 11,21, more common in boys, no obvious seasonality, may have hematuria, frequent urination, urgency and dysuria, gross hematuria, about 3 to 7 Days, microscopic hematuria can last for about 2 weeks.
(4) Others: Infantile diarrhea, pericarditis, chronic interstitial fibrosis, rubella-like disease and congenital malformations have been found to be associated with adenovirus infection. It has been reported that in addition to causing respiratory tract after organ transplantation and immunodeficiency of adenovirus infection, Urinary tract infections can also cause central nervous system infections such as encephalitis.
2. Common clinical manifestations of adults
(1) Respiratory tract infections: common manifestations of atypical pneumonia, may have fever, cough, sore throat, salivation, lung voice, X-ray chest showed interstitial pneumonia changes, mostly unilateral, lower lung field More common, a small amount of pleural effusion can occur, the course of the disease is often self-limiting (about 1-2 weeks), rare secondary bacterial infection or death.
(2) Epidemic keratoconjunctivitis is caused by adenovirus type 8,19. Other types are only sporadic cases, which are transmitted through contaminated public towels, contaminated hands, eye drops, etc., incubation period 3~24 Days, insidious onset, more involved in both eyes, eye irritation symptoms and increased secretions, sustainable for 1 to 4 weeks, corneal damage can last for several months, rare blindness, common family transmission.
Examine
Adenovirus infection check
The total number of white blood cells is normal or slightly reduced, and lymphocytes are relatively elevated.
In patients with pneumonia, X-ray chest radiographs have flaky infiltration on one side or both sides, and there may be a small amount of pleural effusion.
Diagnosis
Diagnosis and identification of adenovirus infection
Diagnostic criteria
In addition to epidemiological and clinical manifestations, diagnosis depends on experimental diagnosis.
1. Rapid diagnosis method Take the pharyngeal exfoliated cell smear, stain with the multivalent adenovirus fluorescent immune serum, and observe by fluorescence microscopy, it can be seen that the bright fluorescence in the exfoliated cell nucleus is positive.
2. Virus isolation According to different clinical types, pharyngeal secretions, sputum, conjunctival scrapings and fresh urine are inoculated into passaged single-layer human epithelial cells. Typical cytopathic lesions can be detected after 2 to 7 days. The coagulation test was set and the test was finalized by neutralization test.
3. Serological examination takes both acute and convalescent sera, complement-binding antibodies, neutralizing antibodies and hemagglutination-suppressing antibodies. If there is a 4-fold increase, the complement-binding antibodies are group-specific antibodies, neutralizing antibodies and blood. The coagulation-inhibiting antibody is a type-specific antibody. After one week of infection, the antibody titer increases, and the complement-binding antibody decreases or disappears one year after infection. The neutralizing antibody persists for at least 10 years, and the titer does not decrease. Some people think that hemorrhagic bladder The neutralizing antibody titer of a single serum adenovirus type 11 or 21 in an inflammatory patient can be confirmed by a titer of 1:32, and the adenovirus positive rate is higher by using a digoxin-labeled nucleic acid probe. It is differentiated from herpes virus, poxvirus, flu, parainfluenza, and rhinovirus infection.
