epidemic keratoconjunctivitis
Introduction
Introduction to epidemic keratoconjunctivitis Epidemic keratoconjunctivitis is an infectious eye disease caused by a viral infection. It is an acute conjunctival and corneal disorder that can be prevalent throughout the world and in all seasons. The pathogenic pathogen of epidemic keratoconjunctivitis is adenovirus, which is the most common form of adenovirus type 8 and often causes outbreaks. Adenovirus type 8 is the main pathogen of epidemic keratoconjunctivitis. After the conjunctival inflammation subsides, sometimes the patient still feels the light, tears, foreign body sensation and blurred vision. The course of the disease can be several months or years. After the infiltration is gradually absorbed, the thin tendon can be left at different levels, which generally has no significant effect on vision. . basic knowledge Sickness ratio: 0.5% Susceptible people: no special people Mode of infection: contact spread Complications: stress ulcers
Cause
Cause of epidemic keratoconjunctivitis
Adenovirus infection (80%):
It is caused by adenovirus type 8, type 19 and type 37. Among them, type 8 is more common and highly contagious. It has caused worldwide prevalence.
The adenovirus is composed of a core and a capsid having a icosahedral structure of about 60 to 90 nm in diameter. The core consists of linear double-stranded DNA and four other related proteins. The capsid is composed of 252 sub-particles of 12 proteins, of which 240 are hexon, 12 are penta, and five are made of 1 fiber. And the polygonal base and the nodule at the distal end of the fiber constitute a specific antigenic determinant for both the pentad and the hexon. Since the isolation of adenovirus in 1953, six subgroups of 47 serotypes have been discovered. There are mainly group D (types 8,19 and 37, a few caused by 9,10,13,15,20,22-24,29) in group C (types 1, 2, 5, 6). , group B (3, 7, a few caused by type 11, 14, 16, 21) and group E (type 4). A total of 19 serotypes can cause adenovirus-infected eye disease, and clinical symptoms closely related to serotype are epidemic keratoconjunctivitis (Ad8,9,37) pharyngeal conjunctival fever (Ad3,7), non-specific follicular conjunctivitis (Ad1, 2, 4, 5, 6). Despite the close association between serotype and clinical manifestations, there are many exceptions, and many serotypes can cause mild follicular conjunctivitis.
1. Adenovirus (Ad) is a very extensive group of DNA viruses that reproduce mainly in the nucleus. In addition to infecting the conjunctiva, corneal epithelium, and pharyngeal and lymphoid tissues, it can also multiply in the intestines. A total of 80 serotypes have been identified to date, of which 21 serotypes were infected, of which EKC was caused by Ad7,8,1937; pharyngeal-conjunctival heat was caused by Ad3,4,7; general follicular conjunctivitis It is caused by Ad111, 1417,19,20.
2, EKC, PCF conjunctivitis and superficial punctate keratitis are the direct result of Ad infection; subepithelial infiltration is caused by immune response.
Pathogenesis
The virus invades the cells and multiplies in the nucleus, and its replication and spread can directly cause damage to the infected cells. The process may be mediated by the body's immune response. Mucosal hemorrhage, edema exudation and cell infiltration occur in pathological changes. Some cells undergo degeneration, necrosis and shedding, and inclusion bodies are visible in the cytoplasm and nucleus.
Prevention
Epidemic keratoconjunctivitis prevention
During the epidemic, its main measures were:
1 personal hygiene: do not use dirty hands to blink, implement a separate towel basin;
2 public health: strict management of swimming pools, bathrooms, hairdressers, and baths and washbasins in collective units;
3 Isolation of infectious sources: isolation measures should be taken for patients to prevent transmission. During the epidemic, the quarantine work should be strengthened for stations and terminals, and patient outflows should be strictly prohibited;
4 Do not use preventive eye drops in the absence of a valid antiviral drug to cross-infect rabbits;
5 Strengthen disinfection work: Enterovirus is sensitive to heat and dryness. It can be inactivated by heating to 60 ° C minutes. Common disinfectants such as alcohol (50% 30 seconds, 70% 10 less, 90% 10 seconds), iodine ( 0.2% PA iodine 1 minute), carbolic acid (1% 5 minutes) and cresol (3% 15 minutes) have good inactivation, it is recommended to wash hands with 70% alcohol (90% irritating) Waiting for drying, as a disinfection measure, clinical experiments prove that the use of interferon eye can prevent the occurrence of this disease, due to the high economic value, there is no practical application value during the pandemic.
Complication
Complications of epidemic keratoconjunctivitis Complications, stress ulcers
There is no effective method for the prevention of complications of the nervous system. During the period of AHC, avoiding fatigue and prohibiting intramuscular injection may have a certain effect on alleviating symptoms or reducing the occurrence of the complication.
Symptom
Epidemic keratoconjunctivitis symptoms Common symptoms Spotted bleeding Visual impairment Throat sore throat Pharyngeal hyperemia Upper fever Yellow white Small conjunctiva Congestive chills Scleral bleeding
Initially for acute follicular conjunctivitis, followed by keratitis.
1, acute conjunctivitis: incubation period of 5 to 12 days, mostly bilateral, one eye first, often accompanied by headache, fatigue, low fever and other systemic symptoms, consciously have foreign body sensation, itching, but less secretion, and water sample 1, 1/3 of the patient's conjunctiva can be seen on the pseudomembrane, the conjunctiva is highly congested. Edema, there are many round follicles in the conjunctiva and ankle of the lower jaw. Sometimes there may be punctiform hemorrhage under the conjunctiva. The lymph nodes in the ear are swollen and tender. After about 5-7 days, the symptoms of conjunctivitis gradually subsided.
2, shallow punctate keratitis: after the conjunctival inflammation subsides, sometimes the patient is still afraid of light, tears, foreign body sensation and blurred vision, the course of disease can be several months or years, after the infiltration gradually absorbed, often can leave different degrees The thinness of the sputum generally has no major impact on vision.
Examine
Examination of epidemic keratoconjunctivitis
At the time of examination, after staining with 1% fluorescein, there were many scattered spots in the central area of the cornea under the slit lamp, and there was a circular infiltration point under the epithelium, which lifted the epithelium slightly, but did not form an ulcer.
Diagnosis
Diagnosis and differentiation of epidemic keratoconjunctivitis
diagnosis
For patients with acute follicular conjunctivitis, epidemic keratoconjunctivitis should be excluded. Conjunctival sac secretions were stained with genus, and epidemic keratoconjunctivitis showed lymphocytes, degenerative epithelial cells and many nucleated white blood cells. Those with pseudomembrane formation are mainly polymorphonuclear leukocytes. Virus isolation can make a definitive diagnosis, but it must be cultured early. Most patients are positive in the first week and then significantly reduced in the future. Direct and indirect immunofluorescence tests for conjunctival epithelial scrapers are simple and reliable diagnostic methods.
1. Have a history of contact with the patient;
2. Typical ocular symptoms and signs and enlarged lymph nodes in the ear;
3. The secretion smear mononuclear cells;
4. The secretion or scraper is examined by a polymylon reaction technique to detect the pathogen.
Differential diagnosis
Mainly associated with acute hemorrhagic conjunctivitis, Thygeson's superficial punctate keratitis, acute catarrhal conjunctivitis.
