What Is Adenovirus?

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Adenoviruses commonly cause mild cold or flu-like symptoms in humans. The virus can be transmitted from person to person year-round, in people of all ages. An adenovirus may cause various types of illness; for example, cold-like symptoms, fever, sore throat, diarrhea, conjunctivitis (pink eye), bronchitis, or even pneumonia.

People most at risk of getting sick from exposure to an adenovirus are those with a weakened immune system (such as seniors or young children) people with respiratory disorders such as asthma or chronic obstructive pulmonary disease (COPD), and those with heart disease.

Sick at home with high fever
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Types of Adenoviruses

Over 100 variations of adenoviruses have been identified, and 49 types are capable of infecting human hosts. The Centers for Disease Control and Protection (CDC) categorizes adenoviruses according to those that can cause outbreaks. These include:

  • Adenovirus types 3, 4, and 7 are commonly responsible for acute (severe and short-lived) respiratory infections. 
  • Adenovirus type 7 has been linked with more severe symptoms and conditions (including death) than any of the other adenoviruses in the U.S.
  • Adenovirus type 14 has been responsible for outbreaks of acute respiratory illness among military recruits (as well as in the public).
  • Epidemic keratoconjunctivitis, an eye infection that affects the conjunctivae (the white area of the eye) and the cornea (the clear coating of the eye) is known to be caused by several types of adenoviruses, including 8, 19, 37, 53, and 54.
  • Enteric adenoviruses, types 40 and 41, are known to cause gastroenteritis (an inflammation of the stomach and intestines), particularly in children.
  •  Adenovirus type 4 and 7 are known to spread particularly fast in water (such as in small lakes or pools) and have caused outbreaks of febrile disease as well as conjunctivitis in pools that are not adequately treated with chlorine.

While animals also host types of adenoviruses, humans do not usually contract these from animals.

Adenovirus Symptoms

Adenoviruses can cause a wide range of symptoms from various illnesses, these include the following.

Common cold and flu symptoms such as:

  • Fever or chills
  • Sore throat
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue (tiredness)
  • Runny or stuffy nose
  • Body aches or muscle pain
  • Headache

Symptoms of acute bronchitis or bronchiolitis (inflammation of the airways of the lungs, sometimes referred to as a “chest cold”) may include:

  • Cough
  • Mucus production (which could be white, yellowish-gray, or greenish colored)
  • Fatigue
  • Shortness of breath
  • Low-grade fever and chills
  • Chest discomfort

Symptoms of pneumonia, which may include:

  • Cough (which may be productive, involving yellow or greenish mucus production)
  • Fever with chills and/or sweating
  • Shortness of breath (rapid, shallow breathing)
  • Pain in the chest that is stabbing or sharp and worsens when breathing deep
  • Fatigue (loss of energy)
  • Loss of appetite

Symptoms of conjunctivitis caused by adenovirus may include:

  • Irritation of the eye or eyes
  • Photophobia (sensitivity to light)
  • Watery discharge from the eye or eyes
  • Sensation of having a foreign body in the eye (due to the involvement of the cornea)
  • Corneal inflammation
  • Corneal opacities (loss of normal transparency of the eye due to infection or other causes)
  • Decreased vision (blurred or hazy) in severe cases

Symptoms of acute gastritis (inflammation of the stomach or intestines) caused by adenovirus may include:

  • Nausea and vomiting
  • Diarrhea
  • Stomach cramps or discomfort

Symptoms in Children

Adenoviruses commonly cause several types of infections in children, including:

  • Respiratory conditions
  • Conjunctivitis
  • Croup (inflammation and swelling in the area of the vocal cords)
  • Bronchiolitis (inflammation of the small airways in the lungs)
  • Pneumonia

Most commonly, children get respiratory conditions from adenoviruses (such as colds, croup, bronchiolitis, and pneumonia), but occasionally they can get infections of the digestive tract (gastroenteritis).

Common symptoms of adenovirus infections in children may begin two to 14 days after exposure and may include:

  • Cough
  • Fever
  • Runny nose
  • Sore throat
  • Headache
  • Swollen glands
  • Symptoms of conjunctivitis (pink eye)
  • Vomiting
  • Diarrhea that becomes watery and starts suddenly
  • Abdominal cramps

If your child has symptoms of an adenovirus infection, be sure to consult with your pediatrician or other healthcare provider as soon as possible for a diagnosis.

Rare Symptoms

Less common symptoms of adenovirus infections could include bladder infections or nervous system infections.

Symptoms of a bladder infection include:

  • Frequent urination
  • Burning or pain when urinating
  • Blood in the urine

Symptoms of infection of the brain or spinal cord (such as meningitis and encephalitis) may include:

  • Nausea and vomiting
  • Fever
  • Headache
  • Stiffness of the neck

Causes

An adenovirus is an infectious agent that is very small. In fact, it cannot even be seen by light microscopy. It can only multiply within the live cells of a host. Adenoviruses are very resilient. They can live for long periods of time outside of the host.

Adenoviruses spread from one infected person to another. These viruses can result in mild illness (such as a respiratory infection), or, less commonly, severe illness (such as meningitis).

People who have a compromised immune system (such as infants, seniors, or those with disorders that weaken the immune system), as well as those with existing heart disease or respiratory disorders (such as COPD or asthma) are at high risk of developing serious illness from an adenovirus infection.

There are several common ways to become infected with adenovirus. These may include:

  • Close personal contact (touching or handshakes)
  • Coughing or sneezing
  • Touching the nose, mouth, or eyes (without washing your hands) after contact with objects that an infected person has touched or after direct contact with a person infected with the virus
  • Direct contact with an infected person’s stool (such as when changing a diaper)

Adenoviruses are resistant to many types of cleaners and disinfectants and can live on inanimate objects for long periods of time. It’s important to use a disinfectant known to kill adenoviruses, such as a bleach-based solution, if there is an adenovirus case in your household or an outbreak in a facility such as a school or nursing home.

Causes in Children

Late winter, spring, and early summer are the most common seasons for adenovirus infections, but they can occur anytime during the year. Adenoviruses are commonly spread in children by:

  • Respiratory infections are spread when fluid from the mouth, throat, or lungs that contains the virus is ejected via couging or sneezing on another person.
  • Adenoviruses can be spread by touching objects contaminated by an adenovirus (such as toys) then touching the nose, mouth, or eyes without washing one’s hands. Adenoviruses can live for many hours on toys, countertops, doorknobs, and other inanimate objects.
  • Digestive tract infections are spread by oral-fecal transmission (not washing hands properly after using the bathroom or eating or drinking food or water that has been contaminated).

Children ages 6 months to 2 years of age who are in childcare facilities on a regular basis are the most likely to contract adenovirus infections. In children under age 5, adenovirus infections most commonly affect the digestive tract. By age 10, most children have had one or more infections caused by an adenovirus.

Diagnosis

Usually, the healthcare provider will do an examination, take a history of the current symptoms, and make a diagnosis based on this information. If an adenovirus infection causes a sore throat, it’s common for a strep test to be obtained to rule out other underlying causes of the infection.

Special diagnostic tests can be done to detect and identify specific viruses (including adenoviruses) but these tests are expensive. Because there is currently no proven medical treatment for adenovirus infection, it is often considered a waste of time, expense, and the discomfort of obtaining specimens for diagnostic purposes.

On the other hand, if a person is very ill, the healthcare provider may obtain samples from various regions of the body (such as the eyes, throat, stool, blood, or urine) to identify the presence of adenoviruses.

Respiratory Infections

If a test is ordered to evaluate the underlying pathogen (germ) causing a respiratory infection, a specimen will be obtained by swabbing the back of the throat via the nose or the mouth. The swab is sent to the lab for testing.

If a specimen is taken from the nose, the method of testing is referred to as a nasopharyngeal swab. This involves using a special cotton swab to collect a specimen inside both sides of the nose by swabbing for approximately 15 seconds.

An oropharyngeal (throat) specimen may be collected; this involves vigorously swabbing the area around the tonsils and the back of the mouth and throat. The swab is rotated several times.

When a lower respiratory infection (such as viral pneumonia) is suspected, the healthcare provider may ask for a sputum specimen. This involves coughing up some mucus for lab evaluation. A blood specimen could also be ordered to diagnose adenoviruses under some circumstances.

Adenoviral Eye Infections

If there is clinical evidence of a conjunctivitis or corneal eye infection, your healthcare provider may obtain a conjunctival swab specimen for lab evaluation by using a wood-tipped applicator with a topical numbing agent and normal saline for moisturization.

Specimens for diagnosis of adenoviruses should be collected within seven days of the onset of symptoms.

Treatment

There is no specific medical treatment (such as antiviral medication) to treat an adenovirus infection. Medical treatment is not required for most adenovirus infections. They are usually mild and require minimal intervention to relieve symptoms and prevent complications (such as drinking plenty of fluids to prevent dehydration).

Treatment of Adenovirus Symptoms in Children

There are some things you can do to help your child feel better while preventing serious complications from the infection. These interventions depend on your child’s age, symptoms and general health.

Encourage fluids. Water, formula, breast milk, or electrolyte-containing fluids are recommended for rehydration for children. Avoid giving young children sugars, soda, juices, or sports drinks to rehydrate.

A child who is unable to drink or hold down fluids is at risk for dehydration and may need to be hospitalized; in this instance, it’s important to consult with a healthcare provider as soon as possible.

If needed, intravenous fluids will be given via an IV line (which is administered in a clinical setting). The IV therapy will ensure your child has enough fluids and electrolytes to prevent severe complications, such as dehydration.

Encourage healthy solid foods as tolerated, If your child has diarrhea, consult with the healthcare provider about which types of foods are best.

Give medications as ordered by the healthcare provider to treat symptoms, such as inhalers (bronchodilators) to help open airways and improve the flow of oxygen in the lungs. Bronchodilators can also be given via a mini nebulizer, which is a machine that delivers a fine mist of medication through a mask placed over the child’s face.

Administer supplemental oxygen if ordered by the healthcare provider. This can be given through a mask, nasal prongs, or an oxygen tent.

Prevention

There is a vaccine for certain types of adenoviruses, but the vaccine is only available to the military. It is not given to the general population because it has not been adequately studied in those with weakened immune systems, infants, children, or people who are pregnant or breastfeeding.

There are some common ways to help to prevent getting ill from the virus, these include:

  • Meticulous handwashing (scrub with soap for at least 20 seconds, then rinse with water that is as hot as can be tolerated)
  • Avoiding touching your face, eyes, nose or mouth (unless you have just washed your hands)
  • Avoiding close contact with those who are ill
  • Teaching your children how to adequately wash their hands (the 20-second rule)
  • Staying home when ill, covering your mouth when you cough or sneeze and avoiding sharing cups or eating utensils (to help protect others from the infection)

A Word From Verywell

Adenoviruses can cause outbreaks at any time of year. The most common illnesses caused include respiratory illness and viral conjunctivitis. But the statistics on the incidence of adenovirus infections are somewhat skewed because these illnesses are not required to be reported to the CDC.

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