Enterovirus: Strains, How It Spreads, and Prevention Strategies

Enteroviruses (EVs) are a group of viruses that cause a variety of contagious illnesses. At least 106 enteroviruses are known to infect humans. Most enterovirus cases do not cause symptoms, but some have the potential to cause dangerous conditions and diseases, such as encephalitis (inflammation of the brain), and myocarditis (inflammation of the heart muscle).

The EV poliovirus, which causes polio, is the only enterovirus infection that can be prevented, thanks to the polio vaccine. You may not be able to avoid enterovirus infections completely, but you can reduce your risk by practicing good hygiene and avoiding others who are sick.

This article discusses the causes and symptoms of enterovirus infections, how they are treated, and several ways you can protect yourself from getting sick.

Overview of Enterovirus Infections

Enterovirus infection is common. Each year in the United States, between 10 and 15 million people have an enterovirus infection. Most people who get infected with these viruses do not get sick.

Enteroviruses can exist in a person's stool, saliva, mucus, or fluid from blisters. They can also survive on surfaces for several days.

The most common way to catch an enterovirus is to come in contact with an infected person's respiratory fluids—for example, if they cough or sneeze. You can also catch an enterovirus by:

• Touching a contaminated surface then touching your eyes, nose, or mouth
• Changing someone's diaper who is infected, then touching your eyes, nose, or mouth
• Kissing, hugging, sharing utensils, or shaking hands with someone who is infected
• Drinking contaminated food or water

Mothers can also pass an enterovirus to their children during childbirth or breastfeeding.

Even if you have no symptoms, you can be contagious with an enterovirus for several weeks. From the time you are infected, it can take between three days and three weeks before symptoms first appear.

Enterovirus Strains

Some types of enteroviruses may be more likely to cause certain symptoms and illnesses than others. Over 100 strains of enteroviruses have been identified, including the following:

• Enterovirus D68 is one of many enterovirus sub-types that usually causes mild respiratory symptoms in adults, such as coughing and sneezing, but can be more serious in children and people with weakened immune systems.
• Poliovirus is responsible for polio—the deadly disease that causes paralysis when the spine is infected. All but two countries have completely eliminated polio through vaccines and close monitoring of outbreaks.
• Rhinovirus is the most common cause of the cold. Rhinoviruses are also known to cause sinus and ear infections, and asthma attacks.
• Coxsackievirus is the most common cause of hand, foot, and mouth disease. This condition mostly affects children, resulting in mouth sores and rashes on the hands and feet.
• Echoviruses are also common and most cases are mild. But echovirus can also infect the central nervous system (brain and spinal cord), resulting in life-threatening complications.

What Are the Symptoms of Enterovirus?

If you have an enterovirus infection, the symptoms you develop largely depend on how the enterovirus strain interacts with your body and how strong your immune system is.

For most people, enterovirus infection causes mild symptoms, if any at all. When symptoms do appear, they may affect one of the following areas:

• Gastrointestinal system: Infections can lead to diarrhea, nausea and vomiting, abdominal pain, cramping, constipation, and bloating.
• Skin: Mild to severe rashes, open sores, changes in skin coloration, mouth blisters, and other skin-related symptoms are also possible.
• Respiratory system: Symptoms may resemble a common cold or respiratory infection, with coughing, sneezing and runny nose, wheezing, and difficulty breathing.
• Central nervous system: When the enterovirus spreads into the central nervous system, symptoms can include paralysis, slurred speech, difficulty walking, and other symptoms known collectively as ataxia.

An enterovirus infection generally begins in your stomach and then moves to your intestines, resulting in mild, flu-like symptoms.

If the virus infects your central nervous system, you can develop serious and life-threatening conditions like paralysis and meningitis—a condition that causes inflammation around the brain.

Young children and people who are immunocompromised are most likely to develop serious enterovirus complications, as their immune systems are not strong enough to stop enteroviruses from infecting their bloodstream, brain, and other body systems.

Enterovirus Illnesses

Most immune systems are well-equipped to protect against severe enterovirus infections. Certain virus strains may be more likely to cause serious symptoms in children but no symptoms in adults.

More serious enterovirus infections can lead to the following illnesses:

Herpangina

Severe coxsackievirus, echovirus, and enterovirus 71 (EV71) infections are known to cause herpangina. The main symptom of herpangina is blisters that form in the back of the mouth and near the tonsils. Other symptoms include a sore throat and fever.

Children are more likely to develop herpangina than adults. Most of the time, herpangina blisters heal in about a week. Ones that don't can become chronic ulcers.

Hand, Foot, and Mouth Disease

Hand, foot, and mouth disease (HFMD) is an illness that primarily affects children ages 5 and under. HFMD causes a fever and clear or gray blisters on the hands, feet, and mouth that are surrounded by red rings. Blisters can be painful for about a week.

Out of all enteroviruses, coxsackievirus A16 seems to cause hand, foot, and mouth disease most. In 2011, a coxsackievirus A6 outbreak at a daycare caused 99 children to become sick with HFMD, seven of whom needed to be hospitalized.

Acute Hemorrhagic Conjunctivitis

Conjunctivitis is often referred to as pink eye. The symptoms of acute hemorrhagic conjunctivitis (AHC) come on fast and include painful, swollen, and red eyes that water excessively. Symptoms tend to resolve within two weeks at most, usually without long-term eye problems.

Two enteroviruses known for causing AHC are coxsackievirus A24 and enterovirus 70.

Encephalitis

Encephalitis is inflammation of the brain. Symptoms include blindness, coma, seizures, and loss of movement or coordination. Around 10% of people who get encephalitis do not survive.

In Asia, large outbreaks of EV71 that led to encephalitis have cost many children their lives. Some children develop encephalitis of the brainstem, which is considered the most serious form.

Two EV71 vaccines are available in China and have been shown to be effective in preventing encephalitis. There are no FDA-approved vaccines available for use in the United States.

Myopericarditis

Myopericarditis is inflammation of the heart muscle and the sac surrounding the heart—a structure known as the pericardium. The enteroviruses that most often cause it include coxsackieviruses B3 and B2.

Symptoms of myopericarditis include shortness of breath, fatigue, and chest pain. Symptoms can mimic the feeling of having a heart attack and may worsen when lying down.

Some patients who develop severe myopericarditis go into heart failure as excess fluid builds up in their lungs. This can be life-threatening.

Viral (Aseptic) Meningitis

Meningitis is the inflammation of the membranes that surround the brain and spinal cord. Echoviruses 13, 18, and 30 are most known for causing viral meningitis. Like other enteroviruses, viral meningitis is most likely to occur in young children and people with weakened immune systems.

People with viral meningitis develop tiredness, fever, headache, and sometimes confusion. They may lose consciousness and have impaired function. Mild viral meningitis often resolves on its own within seven to 10 days without treatment.

Neonatal Viral Sepsis

Viral sepsis occurs when the immune system attacks its own tissues rather than the virus. Neonatal viral sepsis (NVS) is sepsis that specifically affects newborns.

Two enteroviruses that are most likely to cause NVS are echoviruses and types of coxsackievirus B.

Signs of sepsis in newborns include difficulty breathing, yellowed skin and eyes (jaundice), trouble feeding, lethargy, and extreme fussiness.

Pleurodynia

Pleurodynia is a painful condition in which the lining that surrounds the lungs becomes inflamed. Chest or abdominal pain tends to begin suddenly and may be accompanied by a fever.

For most adults with pleurodynia, symptoms will resolve within a few days. Pleurodynia infection in children is more serious and can be deadly.

The enteroviruses that are most likely to cause pleurodynia are echoviruses and coxsackieviruses.

EV-D68 Infection

Enterovirus D68 (EV-D68) causes symptoms that are similar to the common cold. In some cases, it can develop into a severe infection that requires hospitalization.

Symptoms of EV-D68 infection include difficulty breathing and wheezing. Children with the infection can become weak in their arms and legs. Eventually, this may lead to acute flaccid paralysis. Fewer than one in four people develop a fever.

Children who have asthma are at a higher risk of complications with EV-D68 infection.

How Do You Get Rid of Enterovirus?

Since most enterovirus infections are mild, doctors don't typically do lab tests to find out which strain is making you sick. Unless your illness is unusual or severe, your doctor may treat you based on your symptoms.

There is no specific medication that targets enteroviruses themselves. Resting, drinking plenty of fluids, and taking over-the-counter medications can often relieve mild symptoms of enterovirus infections at home.

People who develop meningitis, encephalitis, or viral sepsis may be prescribed antiviral medication to stop the virus from reproducing. Other forms of infection, like EV-D68, may not respond to antiviral medication.

Supportive care is given to hospitalized people whose enterovirus infection does not respond to other treatments. The goal of supportive care is to relieve symptoms until the virus has passed. For example, people with severe respiratory symptoms may be put on a ventilator to help them breathe.

Preventing Enterovirus Infections

The only enterovirus that can be avoided with a vaccine is the poliovirus. There are no vaccines available in the United States to prevent non-polio enterovirus infections.

Without a specific treatment for enteroviruses, the best thing you can do is prevent yourself from coming in contact with them.

First and foremost, wash your hands often—especially before eating, when using a bathroom, changing diapers, or visiting anyone who is ill.

If available, wash your hands with soap and water or carry an alcohol-based hand sanitizer with you. Avoid shaking hands as much as possible and try not to touch your face.

Keep in mind that you can have an enterovirus infection and not know it. Furthermore, the same virus that gives you cold-like symptoms may cause severe symptoms in an immunocompromised individual you come in contact with.

For your own health and out of courtesy to others, wash your hands often whether you feel sick or not. Remember to cover your coughs and sneezes with a tissue or your upper sleeve, and keep surfaces around your home and workspace clean.

Summary

Enterovirus infections are common, but they don't always cause symptoms. Young children and people with weakened immune systems are most likely to develop serious illnesses if the virus infects their central nervous system.

Enteroviruses are passed between people through direct or indirect contact. There is no specific treatment for enteroviruses, but you can help prevent infection by washing your hands often and keeping a safe distance from others when you are sick.