Picornavirus keratitis

Introduction to picornavirus keratitis Acute hemorrhagic conjunctival keratitis caused by picornavirus, also known as epithelial keratitis (picornaviralkeratitis), is a highly contagious acute conjunctival keratitis that has caused outbreaks in many countries and regions around the world. . The disease has a rapid onset, strong contagious and may be associated with subconjunctival hemorrhage and corneal epithelial damage. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: contact spread Complications: headache muscle atrophy

The cause of picornavirus keratitis

Viral infection (50%):

The disease is caused by enterovirus type 70 (EV70) or coxsackie virus A type 24 (CA24v) in the genus of picornavirus. The virus is 20 to 30 nm in diameter and was first discovered in 1969. Nearly 1 million people worldwide have contracted the disease. After the virus enters the human body through the intestines or respiratory tract, it propagates and replicates in the small intestine, epithelial cells of the pharynx and nearby lymphoid tissues. After reaching a certain level, it invades the blood circulation and forms the first (secondary) viremia. At this time, the patient may appear. Mild discomfort or no symptoms, the virus enters various target tissues with blood flow, and continues to multiply in it, causing damage to the tissue cells; at the same time, it invades the blood circulation again (2nd or major viremia), making various target tissues Once again, it is attacked by viruses. Clinical symptoms usually occur after the occurrence of tissue damage and the second viremia.

Tissue damage (20%):

Inhibition factors are mainly produced by intracellular replication of viruses, which inhibit the synthesis of ribonucleic acid and protein, leading to cell destruction. However, in some enteroviruses, tissue damage caused by immune response may be the cause of disease prolongation, such as in myocarditis. Early tissue damage may be caused by viral replication, and later lesions are associated with immune responses.

MicroRNA keratitis prevention

During the epidemic, its main measures were:

1. Personal hygiene: Do not use dirty hands to blink, implement a separate towel.

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 period, quarantine work should be strengthened for stations and terminals, and patient outflows are strictly prohibited.

4. Do not use "prophylactic eye drops" before using anti-viral drugs that are definitely effective to avoid cross-infection.

5. Strengthen disinfection work: Commonly used disinfectants such as alcohol (50%, 30s; 70%, 10s; 90%, 10s), phenol (1%, 5min) and cresol (3%, 15min) have better Inactivation, it is recommended to use 70% alcohol (90% irritating too strong) to wash your hands and wait for drying as a disinfection measure.

6. Clinical trials have shown that the use of interferon eye can prevent the occurrence of this disease, due to the high cost, there is no practical application value during the pandemic.

Complications of picornavirus keratitis Complications, headache, muscle atrophy

Neurological complications are rare in clinical practice, and the comprehensive literature reports that the complications have the following characteristics:

1. More often occurs in adult males.

2. It usually occurs 2 to 3 weeks after conjunctivitis.

3. The prodromal symptoms are fever, burnout, headache and flu-like symptoms.

4. The initial manifestations are symptoms of nerve root irritation and rapid muscle weakness, which manifests as motor paralysis after a few days.

5. The sputum is also flaccid, mainly involving the lower limbs.

6. Severe cases can cause muscle atrophy, and mild or moderate can return to normal.

Although the above-mentioned incidence of neurological complications is very low, it is more serious and can leave permanent paralysis, so it is worthy of caution.

MicroRNA viral keratitis symptoms common symptoms eye pain nasal congestion keratitis lymph node enlargement corneal epithelial erosion tear edema

1. The incubation period is short, generally about 24h, and the longest is no more than 3 days.

2. Conscious symptoms

The onset is urgent, but it can be monocular at the beginning, but it quickly affects both eyes. After the onset, there is a strong foreign body sensation, eye pain and fear of light and tears. The secretion is initially serous, and later becomes mucinous cellulose. 1 to 2 days to the apex, gradually reduced after 3 to 4 days, returned to normal after 7 to 10 days, and some patients developed general malaise, headache, fever, nasal congestion, sore throat and other symptoms.

3. Eye performance

(1) swelling of the eyelids: different in weight and weight, all patients can occur, the swelling is edematous, without red pain, can disappear in a few days.

(2) subconjunctival hemorrhage: the incidence rate is as high as 70% or more, the predilection site is above the iliac crest, the bleeding is mostly spot or flaky, the color is bright red, and in severe cases, it can spread bleeding under the entire conjunctiva, and traumatic subconjunctival hemorrhage Similarly, bleeding occurs within 1 to 2 days, and the light is absorbed by itself for about 1 week. The severe one takes 1 month to be absorbed. Clinically, it is divided into two types according to whether there is bleeding under the conjunctiva:

1 bleeding type, more common in young patients.

2 edema type is seen in elderly patients.

(3) Follicular formation: early due to hyperconjunctival hyperemia is not obvious, after 3 to 4 days to be congested and regressed, it is found that there are more small follicles in the lower iliac crest, less light and lighter than EKC.

(4) corneal lesions:

1 multiple corneal epithelial erosion: the incidence is high, after 3 hours of onset, corneal epithelium can appear multiple epithelial erosion of the tip size, scattered or arranged in strips, flaky distribution, is the main cause of eye pain, foreign body sensation, After 3 to 4 days, it can disappear on its own, and a few last for more than 2 weeks.

2 superficial punctate corneal epithelial lesions (SPK): 30% of patients with conjunctivitis subsided after SPK, usually only a few infiltration points, mostly in the center of the cornea, must be found through the slit lamp microscope, most in 1 ~ After 4 weeks, it disappeared on its own, rarely caused by subepithelial infiltration caused by EKC, and generally did not cause visual impairment. Glucocorticoids could disappear in a few days.

(5) Other symptoms: In most cases, there may be swelling of the lymph nodes before or under the ear, and tenderness. This symptom disappears with the regression of conjunctivitis. In a few cases, the change of iritis may occur.

4. The disease can be caused by two viruses, EV70 and CA24. The clinical manifestations are difficult to distinguish. According to the literature, the subconjunctival hemorrhage caused by CA24 (84%) is lower than that of EV70 (98%) (P=0.01). The degree is also lower than the latter, but the former is more prone to systemic symptoms than the latter.

Examination of picornavirus keratitis

Virus isolation

The virus was isolated from the conjunctival sac of the patient, and the positive rate was the highest on the first day after the disease, and began to decrease after 3 days, and was negative after 5 days.

2. Serological examination

Serum examination can also be used in patients with negative conjunctival virus isolation. The recovery period (about 2 weeks) neutralizing antibody titer is more than 4 times higher than the acute phase to determine the diagnosis.

3. Immunofluorescence rapid diagnosis

Indirect immunofluorescence assay (IFA).

4. Determination of immunoglobulin and complement in tears

Such as IgG, IgM and complement C3 increased more than normal, and IgA normal can help diagnose.

Adverse examinations may be performed to detect other systemic symptoms to rule out other diseases.

Diagnosis and identification of picornavirus keratitis

The disease is not difficult to diagnose in the epidemic period, but in the early stage of epidemics or sporadic cases, if not pay attention, it can be confused with conjunctivitis caused by other viruses (such as epidemic conjunctival keratitis caused by adenovirus type 3, 4, 11) Therefore, it needs to be identified.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.