Acute hemorrhagic conjunctivitis (AHC for short) is a newly discovered eye disease in 1969, caused by enterovirus type 70. It has now spread worldwide and become one of the most common eye diseases in humans. This disease is characterized by rapid onset, high infectivity, and may be accompanied by subconjunctival hemorrhage and corneal epithelial damage.

bubble_chart Pathogen

During the epidemic of this disease, a new type of picornavirus has been isolated in various countries worldwide. The virus is approximately 20–30 nanometers in diameter, spherical, and a single-stranded RNA virus. It is resistant to acid and ether, resistant to idoxuridine, but sensitive to heat, being inactivated when heated to 50°C for one minute. It can grow in Hela cell cultures and human embryonic lung cell media. This virus is a neurotropic virus, and certain strains can cause neurological damage or flaccid paralysis of the lower limbs when inoculated into monkeys intracerebrally or intraspinally. The pathogen responsible for this disease is enterovirus type 70, a member of the picornavirus family. Recently, another enterovirus, Coxsackievirus A24, has also been found to cause similar clinical manifestations.

The disease predominantly occurs in summer and autumn and is primarily transmitted through water or direct contact with pestilence. Humans are generally susceptible to the disease, with no gender differences. It can affect all age groups, though children under 10 years old have a high infection rate but a lower incidence rate, possibly due to subclinical infections. Adults, particularly those aged 20–40, account for over 80% of cases. After recovery, some immunity is retained, but reinfection can still occur.

1. Incubation period The incubation period is short, generally around 24 hours, with a maximum not exceeding 3 days. In cases of accidental laboratory inoculation into the eye, the virus can be isolated from the eye within 18 to 36 hours.

2. Symptoms The onset is acute, initially affecting either one or both eyes but rapidly involving both eyes. Severe symptoms such as intense foreign body sensation, eye pain, photophobia, and tearing appear immediately after onset. The discharge is initially serous and later becomes mucofibrous. Typically, the viral condition peaks within 1–2 days, gradually subsides after 3–4 days, and returns to normal within 7–10 days. A few cases may present with headache, fever, stuffy nose, and sore throat.

3. Objective signs These include eyelid swelling, subconjunctival hemorrhage, multiple corneal epithelial erosions, punctate subepithelial infiltrates, conjunctival congestion, edema, conjunctival follicles, and preauricular lymphadenopathy.

⑴ Eyelid swelling Varies in severity and occurs in all patients. The swelling is edematous, without redness or pain, and typically resolves within a few days.

⑵ Conjunctival manifestations

1) Subconjunctival hemorrhage The incidence rate is as high as 70% or more, hence the name "acute hemorrhagic conjunctivitis." The most common site is the superior temporal region, with hemorrhages appearing as spots or patches of bright red color. In severe cases, the entire subconjunctival area may be affected, resembling traumatic subconjunctival hemorrhage. Hemorrhages usually occur within 1–2 days, with mild cases resolving spontaneously in about a week and severe cases taking up to a month to absorb. Clinically, cases are classified into two types based on the presence of subconjunctival hemorrhage: the hemorrhagic type is more common in younger patients, while the edematous type is seen in older patients.

⑶ Corneal manifestations

1) Multiple corneal epithelial erosions High incidence rate. Within three hours of onset, pinpoint-sized multiple epithelial erosions may appear on the cornea, scattered or arranged in linear or patchy patterns, which are the main cause of eye pain and foreign body sensation. These typically resolve spontaneously within 3–4 days, though a few cases may persist for over two weeks.

2) Punctate subepithelial infiltrates About 30% of patients develop punctate subepithelial infiltrates after conjunctivitis subsides. Usually, only a few infiltrates are present, mostly in the central cornea, detectable only by slit-lamp examination. Most resolve spontaneously within 1–4 weeks without causing visual impairment. Topical corticosteroids can lead to resolution within days.

⑷ Other symptoms Most cases present with preauricular or submandibular lymphadenopathy and tenderness at the onset, which resolves as conjunctivitis subsides. Rare cases may exhibit signs of iritis.

⑸ Neurological complications Clinically very rare. To date, only 35 cases have been reported in India, 8 in Senegal, 33 in Taiwan (China), and 10 in Shanghai. According to Shenye’s literature review, these complications have the following characteristics: ① Mostly occur in adult males; ② Typically develop 2–3 weeks after conjunctivitis; ③ Prodromal symptoms include fever, fatigue, headache, and common cold-like symptoms; ④ Initial manifestations include nerve root irritation and acute muscle weakness, progressing to motor paralysis within days; ⑤ Paralysis is flaccid, primarily affecting the lower limbs; ⑥ Severe cases may lead to muscle atrophy, while grade I or moderate cases can recover fully. Although the incidence of these neurological complications is very low, they are serious and may result in permanent paralysis, warranting vigilance. {|111|}

1. Clinical Diagnosis The diagnosis of this disease is not difficult during a pandemic, but in the early stages of an outbreak or in sporadic cases, it can be confused with conjunctivitis caused by bacteria or other viruses if not carefully considered. The distinguishing features of several major types of acute conjunctivitis are listed in Table 9-8.

Table 9-8 Key Points for Differentiating Common Types of Acute Conjunctivitis

2. Laboratory Diagnosis

⑴Virus isolation: The virus was isolated from the conjunctival sac of patients, with the highest positive rate on the first day after the onset of illness, which began to decline after 3 days and turned negative after 5 days.

(2) Serological examination For those with negative viral isolation in the membrane sac, serological examination can also be used. If the neutralizing antibody titer during the convalescent stage (around 2 weeks) is more than 4 times higher than that during the acute stage, the diagnosis can be confirmed.

bubble_chart Treatment Measures

Antibiotics and sulfonamides Yaodui are basically ineffective for this disease, and corticosteroids can reduce inflammatory reactions. There is currently no effective drug for enteroviruses, only 2-hydroxybeny benzimidazole (HBB) has been shown in tissue culture systems to effectively inhibit enterovirus 70 and coxsackievirus A24 at a concentration of 50 μg/ml, providing an experimental basis for future prevention and treatment of this disease. Domestic reports indicate that washing the eyes with cold saline or using mercury-based eye drops has achieved certain therapeutic effects.

bubble_chart Prevention

During the epidemic, the main measures include: ①Personal hygiene—Avoid rubbing eyes with dirty hands and implement separate towels and basins; ②Public hygiene—Strengthen strict hygiene management of swimming pools, bathhouses, barbershops, and communal bathing and washing facilities in collective units; ③Isolation of pestilence sources—Isolation measures should be taken for patients to prevent spread. During the epidemic, quarantine efforts at stations and docks should be intensified, and the outflow of patients strictly prohibited; ④In the absence of confirmed effective antiviral drugs, avoid indiscriminate use of "preventive eye drops" to prevent cross-infection; ⑤Enhance disinfection—Enteroviruses are sensitive to heat and dryness, and can be inactivated by heating to 60℃ for minutes. Common disinfectants such as alcohol (50% for 30 seconds, 70% for 10 seconds, 90% for 10 seconds), iodine (0.2% PA iodine for 1 minute), carbolic acid (1% for 5 minutes), and cresol (3% for 15 minutes) all have good inactivation effects. It is recommended to use 70% alcohol (90% is too irritating) for hand disinfection and allow it to dry as a disinfectant measure. Clinical trials have shown that interferon eye drops can prevent the occurrence of the disease, but due to high economic costs, they have no practical application value during large-scale epidemics.

There is currently no effective method to prevent neurological complications. During AHC illness, avoiding fatigue and prohibiting intramuscular injections may play a certain role in alleviating symptoms or reducing the occurrence of such complications.