Epidemic keratoconjunctivitis

Introduction to epidemic keratoconjunctivitis Epidemic keratoconjunctivitis (EKC) is an infectious eye disease caused by a viral infection. Its clinical features are rapid onset, conjunctival hyperemia, edema, more follicles, and spotted infiltration of corneal epithelial cells. The pathogenic pathogen of this disease is adenovirus, which is the most common type of adenovirus type VIII, often causing outbreaks. The incubation period is 5 to 12 days, mostly 8 days. Often the incidence of both eyes begins with a single eye. After 2 to 7 days, the other eye is affected. The patient has a foreign body sensation, burning sensation, fear of light, tearing, and mild visual impairment. basic knowledge The proportion of illness: 0.0033% Susceptible people: no special people Mode of infection: contact spread Complications: ball adhesion

Cause of epidemic keratoconjunctivitis

(1) Causes of the disease

The adenovirus is about 60-90 nm in diameter, consisting of a core and a capsid composed of a icosahedral structure. The core consists of linear double-stranded DNA and four other related proteins. The capsid is composed of 252 sub-species of 12 proteins, of which 240 are six. In the ortho, 12 sub-granules are pentagonal, and the five-orientation consists of a fiber and a polygonal base and a nodule at the distal end of the fiber. The five and six hexones have specific antigenic determinants.

Since the isolation of adenovirus in 1953, six subgroups of 47 serotypes have been identified, and the main group of ocular diseases that can cause eye diseases are groups D (types 8, 19 and 37, and a few by 9, 10, 13, 15, 20). , type 22-24, type 29), group C (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 adenoviral infectious eye disease, and clinical symptoms closely related to serotype are epidemic keratoconjunctivitis (Ad8,9,37), pharyngeal conjunctival fever (Ad3,7), non-specific follicular conjunctiva Inflammation (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 mainly propagate in the nucleus. In addition to infecting the conjunctiva, corneal epithelium, pharynx, and lymphoid tissue, it can also multiply in the intestine. So far, a total of 80 serotypes have been found. There are 21 serotypes infecting humans, of which EKC is caused by Ad7, 8, 19, 37; pharyngeal-conjunctival fever is caused by Ad3,4,7; general follicular conjunctivitis is by Ad111 , 14 ~ 17, 19, 20 type caused.

2. EKC, PCF conjunctivitis and superficial punctate keratitis are direct results of Ad infection; subepithelial infiltration is caused by immune response.

(two) pathogenesis

The virus invades the cells and multiplies in the nucleus. The replication and diffusion can directly cause damage to the infected cells. This process may be mediated by the body's immune response. Pathological changes include mucosal hemorrhage, edema, exudation and cell infiltration, and some cells are denatured. Necrosis and shedding, inclusion bodies are visible in the cytoplasm and nucleus.

Epidemic keratoconjunctivitis prevention

1. It has been confirmed that the iodine-containing disinfectant has obvious inhibitory effect on adenovirus. Wash the hand with diluted 1100 times of iodinated povidone (PVP-I2) solution or 200 times of iodinated polyvinyl alcohol (PVA-I2) solution. 30s, soak the medical treatment equipment for 5min, or use the soaked gauze to wipe the diagnosis table, doors and windows, etc., to prevent infection in the hospital.

2. During the epidemic period, we must actively promote prevention and control knowledge, and do a good job in the prevention and control of schools, nurseries, factories, enterprises, institutions, and service industries (hairdressing rooms, bathrooms), and develop effective sanitation management and disinfection and isolation systems.

3. Vaccine has certain value in preventing adenovirus infection. Ad8, 3, and 11 inactivated or attenuated live vaccines have been used in Japan and have achieved certain preventive effects.

Complications of epidemic keratoconjunctivitis Complications

Keratitis, sputum adhesions, etc.

Epidemic keratoconjunctivitis symptoms Common symptoms Visual impairment Tears keratitis Conjunctival hyperemia Corneal epithelial erosion Sore throat Yellow white Small point Muscle sore Corneal sensation Reduce pharyngeal congestion

1. The latency of EKC is 5 to 12 days, mostly 8 days. It often occurs in both eyes and begins to be monocular. After 2 to 7 days, the other eye is involved. The patient has foreign body sensation, burning sensation, fear of light, tearing and mild visual impairment.

(1) systemic manifestations: fever, sore throat, diarrhea, upper respiratory tract infection, pneumonia, etc., this situation is more common in children, adults have less systemic symptoms, more common in front of the ear, submandibular lymph nodes and tenderness .

(2) Conjunctival lesions: There are a large number of follicles formed, above, the lower iliac crest is the most, the conjunctival hyperemia, edema is obvious, the sacral conjunctiva has pseudomembrane formation, watery secretions, aortic conjunctival a little bleeding, sometimes palpebral conjunctiva can appear Flat scars or sputum adhesions.

(3) corneal lesions:

1 peripheral punctate keratitis: 1 day after the onset of conjunctivitis, some patients with localized congestion of the limbus, corresponding to the peripheral corneal keratitis scattered in the surface.

2 Central surface punctate keratitis: about 1 week after onset, surface punctate keratitis also appeared in the central part of the cornea, fluorescein staining under slit lamp, punctate lesions micro-lifted on the corneal surface, the number varies, and some Scattered, some clustered, corneal sensation diminished.

3 subepithelial infiltration: after 2 to 3 weeks of onset, signs of conjunctivitis and superficial punctate keratitis gradually disappear; another subcutaneous infiltration of corneal lesions simultaneously or sequentially, located in the front elastic layer and shallow layer of the matrix The gray-white round or semi-circular infiltrating lesions are 0.2-0.5 mm in diameter (rarely more than 1 mm), and the number varies from several to more than 100. The fluorescein staining is negative and there is no neovascular growth. After several months, it can be absorbed for several years without ulceration. If it occurs in the pupil area, it can cause a certain degree of visual impairment.

4 multiple corneal epithelial erosion: some patients developed diffuse epithelial erosion or filamentous keratopathy after 2 to 3 weeks of conjunctival inflammation subsided, the pathogenesis is unclear, may be related to the reduction of tear secretion of EKC, in addition, Ad8,19 can still be Causes mild anterior uveitis.

2. PCF incubation period of 5 to 6 days, often the incidence of both eyes, can be sequential or simultaneous onset, typical manifestations of conjunctivitis, fever, pharyngitis triad.

(1) conjunctival, keratitis: acute follicular conjunctivitis is the most prominent and the longest clinical manifestation, visible eyelid and conjunctival edema, follicular formation, lower conjunctiva than the upper conjunctiva, some children with cornea can Fine point epithelial infiltration, coiled silk, generally healed with conjunctivitis, no traces, no subcutaneous infiltration.

(2) fever: the general performance is sudden hyperthermia, lasting 4 to 7 days, the degree of fever is related to age, children's temperature rise is more obvious, often accompanied by chills, headache, muscle aches, diarrhea and other symptoms.

(3) pharyngitis: manifested as sore throat and pharyngeal congestion, the incidence rate is not as high as conjunctivitis and fever.

Examination of epidemic keratoconjunctivitis

1. Virus isolation The virus was isolated from the conjunctival sac of the patient, with the highest positive rate (80%) in 8 days, 6 to 10 days (67%), and negative after 11 days.

2. Serological examination with the recovery period neutralizing antibody titer is more than 4 times higher than the acute phase as the basis for diagnosis.

3. Immunofluorescence technology is a faster and simpler method, that is, taking the conjunctival epithelial smear or secretion smear at the peak of disease (about 1 week), and labeling with fluorescein-labeled antibody, infected epithelial cells can be found in almost all cases. There is a virus antigen present.

Using electron microscopy, the patient's tears or conjunctival scrapings can be directly observed under electron microscopy, and viral particles or viral antigens can be directly found, but because of the high price, the clinical application is limited.

Diagnosis and differentiation of epidemic keratoconjunctivitis

The disease is not difficult to diagnose during the epidemic. In this period, patients with conjunctival hyperemia and upper eyelid swelling should be considered first. The final diagnosis depends on the results of virus isolation and serological examination.

In the early stages of epidemics or sporadic cases, it is easily confused with other acute conjunctivitis.

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