Causes of Epidemic Keratoconjunctivitis and How It Is Spread

Epidemic keratoconjunctivitis (EKC), also known as adenoviral keratoconjunctivitis or keratoconjunctivitis epidemica, is a highly contagious eye infection that affects both the cornea (the clear front surface of the eye) and the conjunctiva (the white of the eye). As the name suggests, the disease occurs in clusters in places like schools, camps, and nursing homes.

EKC is caused by a family of viruses known as adenoviruses responsible for many respiratory, gastrointestinal, and eye infections. The diagnosis is based on the red, swollen appearance of the eye, accompanied by an eye swab. EKC is a self-limiting disease that resolves on its own. Treatment focused on easing symptoms and preventing the further spread of infection.

This article describes the causes and symptoms of epidemic keratoconjunctivitis, including how the infection is diagnosed and treated. It also explains how the virus is contagious, how it is spread, and what steps are taken to prevent infection.

What Are Symptoms of Epidemic Keratoconjunctivis? 

Epidemic keratoconjunctivitis follows a specific pattern with symptoms occurring in stages known as the prodromal, acute, and chronic phases.

Prodromal Phase

Prodrome refers to the non-specific, generalized early symptoms that precede the onset of a disease. During this time, a person with EKC may not realize they are infected but can still pass the virus to others.

The prodromal phase for EKC can last anywhere from two days to a week and manifest with flu-like symptoms such as:

• Low-grade fever
• Muscle aches
• Malaise
• Fatigue
• Swollen lymph nodes around the neck

Acute Phase

The acute phase lasts seven to 10 days, causing overt symptoms easily recognized as an eye infection.

The infection will initially be unilateral (affecting one eye) before becoming bilateral (affecting two eyes) in 70% of cases. This almost invariably happens when a person touches their infected eye and then their uninfected eye with the same hand (referred to as self-inoculation).

The acute phase is characterized by inflammation of the conjunctiva with or without the involvement of the cornea, causing symptoms like:

• Eye redness
• Eye soreness and irritation
• A gritty feeling in the eye
• Swelling of the conjunctivitis
• Excessive tearing
• Eye crusting, especially when waking up
• Swelling of the eyelid
• Blurring of vision
• Photophobia (sensitivity to light)

Chronic Phase

The chronic phase affects 50% of people with EKC. It is the period during which the immune system is actively reining and eventually resolves the infection.

Seven to days after the appearance of acute eye symptoms, the cornea can start to be infiltrated by deposits of white blood cells and collagen (called subepithelial corneal infiltrates). This can lead to mild corneal scarring and symptoms like:

• Corneal opacity (clouding), usually mild
• Slight blurring
• Increased tearing

Even after the infection is fully cleared, these symptoms can persist for months and sometimes years. While the damage is rarely permanent, the symptoms can be aggravating.

Possible Complications

Though epidemic keratoconjunctivitis usually only causes temporary corneal opacity, severe infections can cause scarring of the symblepharon formation (where the eyeball meets the eyelid). Damage to this structure can cause discomfort when blinking and reduced teardrop production, leading to keratoconjunctivitis sicca (dry eye syndrome).

Other rare but possible complications include astigmatism in which vision is blurred due to changes in the shape of the cornea.

Severe EKC coupled with aggressive eye rubbing can also cause corneal perforation which, in turn, can lead to a secondary bacterial infection, eye damage, and permanent vision loss.

What Is the Most Common Cause of Epidemic Keratoconjunctivitis?

Epidemic keratoconjunctivitis can be caused by many different adenoviruses. Adenoviruses are a hearty family of viruses able to survive outside of the body for up to 30 days in some cases.

Adenoviruses thrive in the eyes, nasal passages, saliva, and respiratory tract. Their thick protein shells (called capsids) are resistant to environmental conditions, allowing them to be spread from person to person or aerosolized and spread whenever a person sneezes.

Possible modes of transmission include:

• Direct contact with infected teardrops or nasal secretions
• Hand-to-eye contact with infected surfaces
• Being touched by an infected individual
• Sneezing or coughing (particularly in closed spaces)
• Shared personal care items (like eyelash brushes)
• Shared sunglasses

EKC infections tend to occur in clusters, particularly in closed institutions such as schools, daycare centers, hospitals, nursing homes, and workplaces.

The incubation period—the time from exposure to symptoms—can last from two to 14 days. EKC infections are by far the most contagious during the first few days of symptoms but can remain so for up to two weeks.

How Epidemic Keratoconjunctivitis Is Diagnosed

EKC can usually be diagnosed with a simple eye exam. A lighted magnifying glass, called a slip lamp, can check for characteristic signs of EKC, such as corneal opacity and subepithelial infiltrates. The practitioner may also check for swollen lymph nodes in the neck.

A slit lamp in conjunction with magnifying lenses or an ophthalmoscope may be used to check the back of the eye if the symptoms are severe or persistent.

In most cases, treatment would begin if the symptoms are uncomplicated. If the diagnosis is uncertain or the presentation of symptoms is unusual, the healthcare provider can use a simple, in-office test to detect the presence of adenovirus in the eye.

Adenovirus Swab Test

Adenovirus swab tests are highly sensitive rapid tests that can confirm an adenovirus infection within around 10 minutes. Available under such brand names as RP Adeno Detector and AdenoPlus, the test involves running a soft swab between the lower eyelid and conjunctiva to obtain a sample of fluid.

Newer-generation swab tests have a sensitivity of between 95.5% to 98% and a specificity of between 39.5% and 85%. Because of the low specificity, there is a risk of a false-positive result.

The swab test is non-invasive but may cause discomfort. An anesthetic eyedrop may be used for people who dislike having their eyeballs touched.

How Epidemic Keratoconjunctivitis Is Treated

EKC infections usually resolve on their own without treatment. At present, there are no oral or topical antiviral drugs able to clear the infection. Treatment is primarily focused on the relief of symptoms and the prevention of complications.

Among some of the more common treatment options:

• Cold compresses can help reduce eye swelling and discomfort.
• Artificial tears can help keep eyes hydrated and reduce grittiness.
• Vasoconstrictor eye drops are intended for the short-term treatment of eye redness. Overuse can cause rebound redness.
• Cyclosporine eye drops, which suppress the immune system, can help treat persistent corneal opacity,
• Cycloplegic eye drops, like Atropen (atropin), can temporarily dilate the pupils in people with severe photophobia.
• Corticosteroid eye drops are often used in severe EKC infections. Though able to reduce inflammation quickly, they may actually end up prolonging the infection.

How to Prevent Epidemic Keratoconjunctivitis

EKC is a highly contagious disease and one that requires vigilance to prevent further spread of the infection. Children with EKC should stay home from school until symptoms have resolved. Adults can continue to go to work as long as they continue to adhere to infection control measures.

To avoid getting or spreading EKC during an outbreak:

• Avoid touching your eyes. If you do so, wash your hands thoroughly with soap and warm water or an alcohol-based hand sanitizer.
• Avoid touching others. This is especially true in places where outbreaks are common, such as daycare or nursing homes.
• Do not share makeup or towels. Anything that comes into contact with your eyes should not be used by anyone else (or vice versa).
• Cover your mouth when you cough or sneeze. To keep your hands clean, cough or sneeze into the crook of your elbow rather than into your hands.
• Use separate towels for family members. Moreover, until the outbreak is passed, try to wash towels and facecloths as frequently as possible.
• Use disposable tissues to blow your nose. When finished, throw them away immediately.
• Keep surfaces clean. This is especially true in the bathroom where infections commonly spread. Leave an antibacterial cleaner or wipes in the bathroom so that family members can clean up after themselves.
• Wear an eyepatch. If you have to go to work and want to avoid touching your eye, ask your healthcare provider or pharmacist about an eyepatch. Find one that cups the eye softly rather than lying flat against it.

Summary

Epidemic keratoconjunctivitis is a highly contagious viral infection of the clear part of the eye (cornea) and white of the eye (conjunctiva). Caused by a family of viruses known as adenoviruses, the infection is easily passed from person to person, particularly in places like daycare, schools, and nursing homes. Symptoms include eye redness, discomfort, tearing, swelling, and blurring.

From start to finish, EKC infections usually last two weeks. The treatment of EKC is focused on easing symptoms with eye drops and cold compresses. Handwashing and isolation are two key ways to prevent passing the virus to others.