Infectious Conjunctivitis

Infectious conjunctivitis is inflammation of the conjunctiva, which acts as a barrier between the outside and inside of the eye. This inflammation can be caused by bacteria or viruses. Conjunctivitis symptoms can be worse in people with a weakened immune system. Also, if you have viral conjunctivitis, which is highly contagious, you should treat it at home to prevent spreading the disease to others.
The risk of infecting others is different from that of allergic conjunctivitis caused by pollen or house dust.

In this article, we will cover the following topics:

Causes of infectious conjunctivitis
The main types of viral conjunctivitis
How to treat the infection and prevent it from spreading

The conjunctiva is a semi-transparent membrane that covers the white of the eye and the inside of the eyelid, as shown in the diagram. The conjunctiva separates the outside from the inside of the eyeball and allows the eyeball to move because it is not attached to the eyelids.

Conjunctivitis is inflammation of the conjunctiva caused by bacteria or viruses. It has long been one of the most common eye diseases in many patients. If you have any symptoms that concern you, please visit an ophthalmologist.

The conjunctiva is responsible for preventing bacteria and viruses from entering the eye. The conjunctiva’s defensive reaction to exclude foreign substances results in conjunctivitis, which causes redness of the eye and eye discharge.
While the eyelids are open, the conjunctiva is continuously exposed to the outside, making it susceptible to irritation. In addition, the conjunctiva has a bag-like structure that can easily accumulate foreign substances.
However, inflammation is not usually caused by contact with bacteria or viruses. When the conjunctiva is scratched by rubbing the eye strongly or if the eye is in a “dry eye” condition, bacteria and viruses can stick to the conjunctiva and cause inflammation.
In addition to bacteria and viruses, allergens such as pollen and house dust can also cause allergic conjunctivitis in many people.

*For more information on allergic conjunctivitis, please click here.

This section describes the types of conjunctivitis caused by viruses and their symptoms.

Epidemic Keratoconjunctivitis (EKC)

EKC is conjunctivitis caused by infection with adenovirus types 8, 19, 37, etc. In some cases, keratitis (inflammation of the cornea) may also occur.
The subjective symptoms include redness of the eye, eye discharge, tearing, eye pain, and swelling of the lymph nodes.

Acute Hemorrhagic Conjunctivitis (AHC)

Acute hemorrhagic conjunctivitis is primarily caused by infection of the eye with enterovirus 70 and coxsackievirus A24 mutants. It is characterized by the appearance of redness, eye discharge, and a foreign body sensation, and by the acute presence of thin hemorrhages in the whites of the eyes and other parts of the eye. It is highly contagious and once resulted in a worldwide epidemic. There have been no major outbreaks in Japan in recent years.
Symptoms are milder than those of EKC, and complications of keratoconjunctivitis are rare.

Pharyngoconjunctivitis (Pharyngoconjunctival fever /PCF )

Pharyngoconjunctivitis is caused by infection with adenovirus type 3.
Symptoms such as redness of the eyes and eye discharge are weaker than those of epidemic conjunctivitis, but sore throat and fever of 39°C or higher are observed, so caution is required.

Herpetic Conjunctivitis

This conjunctivitis is caused by infection of the eye with the herpes simplex virus and is accompanied by pain with small blisters repeatedly appearing on the eyes, skin, mouth, lips and genitals, etc. These symptoms are mainly seen with the first infection and tend to be particularly common in children. Dendritic lesions on the cornea are a typical feature. Most cases are reported to occur in only one eye.

People with weakened immune systems should be especially careful about infectious conjunctivitis caused by viruses and bacteria. Some viral conjunctivitis is highly contagious, so if you are infected, it is important to avoid spreading it to others, including your family.

Wash your hands frequently to prevent infection

Most cases of viral conjunctivitis are transmitted through the fingers of infected people after they rub their eyes. This is because many viruses are present in tears and eye discharge (eye mucus).

Therefore, it is important not to touch the eyes with dirty hands and avoid rubbing the eyes. For prevention and to prevent passing it on to others, wash your hands thoroughly with running water and soap, especially when putting on and taking off contact lenses.

Use eye drops

Since there are no medicines for viruses such as epidemic keratoconjunctivitis and pharyngoconjunctivitis, it is important to receive antibiotic eye drops to reduce inflammation and prevent secondary infection by bacteria. Be sure to wash your hands before and after using the eye drops. Only apply eye drops to the infected eye to protect the uninfected eye.

However, since antiviral drugs have been developed against the herpes virus, eye ointments or oral medications that are effective in inhibiting viral proliferation should be used.

Use goggles in swimming pools

Pharyngoconjunctivitis can also be transmitted when the virus enters the body of another person through pool water. It is effective to use goggles to reduce the chance of direct eye contact with pool water. Washing the eyes with tap water should be avoided, as it washes away tears and can easily damage the cornea.

If you are infected with viral conjunctivitis, you should take the following actions to avoid passing it on to others.

Stay at home until recovery.

Epidemic keratoconjunctivitis and pharyngo conjunctivitis are highly contagious, so it is best to recuperate at home for one to ten days to prevent infection.
Before going to school or nursery school, a doctor’s permission is required to ensure that the child’s infectiousness has decreased and there is no risk of infecting others.
Even adults who have a lot of contact with others are at high risk of infecting others, so stay at home  is the basic response.

Preventing infection among family members

To prevent infection between family members, it is necessary to frequently disinfect and clean anything that an infected person has touched or used.

<Main measures>

・Various precautions to prevent infection.
・Stop using towels and use paper towels instead.
・Wipe anything you touch with alcohol.
・Clean the bathtub and faucet after bathing.
・Wash your laundry separately from your family members.

Conjunctivitis rarely affects the inside of the eye even if it worsens, but complications may occur and adversely affect vision. In order to avoid complications, conjunctivitis must be treated early and properly.

Mixed Infection

When you have conjunctivitis, your body’s natural defenses against infection become less effective, making you more susceptible to new infections from other bacteria or viruses. This is called a mixed infection, and if you are infected with a strong virus such as adenovirus, it is likely to take a long time to heal.

Corneal opacity

The surface layer of the cornea is similar to the conjunctiva, and if conjunctivitis becomes severe, the cornea may become cloudy. In rare cases, mixed infections can cause corneal clouding, which can lead to impaired vision.

Dry eye

If severe inflammation occurs in the conjunctiva, tear secretion will decrease even after the conjunctiva has healed, making the eyes more prone to dryness and dry eyes, so care must be taken.

*Click here for an article about dry eye.

How long does conjunctivitis remain infectious?

Although it depends on the type of viral conjunctivitis, adenoviruses are particularly contagious and remain infectious for about 10 days if they are attached to furniture. Therefore, even after the symptoms of conjunctivitis have subsided, it is best to stay at home and recuperate for a while. You should take time off school or work until your doctor gives you permission.

Can stress cause conjunctivitis?

Whether or not the conjunctiva becomes inflamed is related to the strength of the immune system, and stress is said to be the greatest enemy of the immune system. To boost your immune system, try to eat a balanced diet, get enough sleep, and do some light exercise.

What are the early symptoms of conjunctivitis to look out for?

The main initial symptoms of conjunctivitis are swelling of the eyelids, bloodshot eyes, and swelling of the conjunctiva. Next, eye discharge will appear, and small protruding papillae will appear on the conjunctiva of the eyelids. If left untreated, the protrusions will grow larger and blood vessels will invade the cornea from the conjunctiva, worsening the symptoms, so please visit an ophthalmologist before the condition becomes severe.