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Human adenoviruses are viruses that cause various illnesses, such as the common cold, pink eye, pneumonia, and acute bronchitis. Adenoviruses can cause mild or severe illness.

According to the Centers for Disease Control and Prevention (CDC), however, severe illness related to adenoviruses is less common.

This article will discuss what human adenoviruses are, the symptoms they may cause, and how to treat them. It will also cover who is most at risk of contracting these viruses and experiencing more severe symptoms.

Adenovirus (highly contagious virus), responsible for: Colds, pharyngitis, bronchitis, pneumonia, gastroenteritis, conjunctivitis and keratitis. Image made from a transmission electron microscopy view.Share on Pinterest
Adenoviruses rarely cause severe illness.
Image credit: Cavallini James/BSIP/Universal Images Group via Getty Images.

According to a 2018 review article, human adenoviruses are viruses that usually affect the eyes or the upper or lower respiratory tract.

The CDC state that adenoviruses can cause several illnesses, including:

There are 49 types of adenovirus that can affect humans. However, one 2020 article states that most adenovirus infections are asymptomatic. This means that people who catch these viruses may not show any symptoms.

According to the CDC, there are a number of different adenoviruses that can cause serious outbreaks. These include:

  • adenovirus types 3, 4, and 7, which cause acute respiratory illnesses
  • adenovirus type 14, which also causes acute respiratory illnesses, especially among people in the United States military
  • adenovirus types 8, 19, 37, 53, and 54, which can cause highly contagious conjunctivitis
  • adenovirus types 40 and 41, which causes gastroenteritis, especially among children

The symptoms can vary depending on which illness a person has. The sections below will outline some potential symptoms by illness in more detail.

Epidemic keratoconjunctivitis

Epidemic keratoconjunctivitis is a highly contagious infection that causes inflammation of the conjunctiva. Adenovirus types 8, 19, 37, 53, and 54 can cause this condition.

It may cause redness over the white part of the eye, as well as the inner upper and lower eyelids.

Some other symptoms of epidemic keratoconjunctivitis include:

  • eye irritation
  • itchy eyes
  • sensitivity to light
  • intermittent blurry vision
  • watery eyes

According to one 2020 article, this condition typically affects one eye and then spreads to the other. It is usually milder in the second eye it affects.

The same article also states that symptoms may last for up to 21 days, and that people are infectious for around 2 weeks.

Treatment

There does not appear to be an effective treatment for keratoconjunctivitis.

However, a person can focus on relieving the symptoms using:

  • artificial tears
  • cool compresses
  • topical antihistamines

Respiratory illnesses

A 2016 study found that most people with an adenovirus infection showed the same respiratory symptoms.

The CDC state that the adenovirus types 3, 4, 7, and 14 can cause various respiratory illnesses.

The majority of people who took part in the 2016 study experienced the following symptoms when they became ill:

  • fever
  • cough
  • shortness of breath
  • nausea or vomiting
  • a runny nose

Treatment

Treatment will typically depend on what type of respiratory infection a person has. However, the following can help with symptom relief:

  • using decongestants
  • resting
  • drinking plenty of fluids
  • using a humidifier
  • breathing in steam from a hot bath or a steam inhaler
  • taking lozenges
  • drinking warm beverages

Viral pneumonia

The adenoviruses 3, 4, 7, and 14 can cause viral pneumonia.

The adenovirus most commonly causes pneumonia in people who have had an organ transplant or bone marrow transplant.

According to the American Lung Foundation, symptoms of viral pneumonia begin gradually and include:

  • fever
  • dry cough
  • headache
  • muscle pain
  • weakness
  • shortness of breath, with rapid, shallow breathing
  • a sharp or stabbing pain in the chest that worsens when breathing deeply or coughing
  • loss of appetite
  • fatigue

Viral pneumonia symptoms tend to get worse within a few days of onset.

Some people may develop a high fever, and their lips may turn slightly blue or slightly purple, depending on skin color. If this occurs, a person should seek medical help.

Treatment

Treatment typically focuses on relieving the symptoms. For example, a person can try:

  • taking aspirin to control the fever
  • taking nonsteroidal anti-inflammatory drugs
  • drinking plenty of fluids
  • drinking warm beverages
  • inhaling steam
  • resting

Acute bronchitis

Acute bronchitis is the result of inflammation of the bronchi in the lungs.

The adenovirus types 3, 4, 7, and 14 can cause this illness.

Some symptoms of acute bronchitis include:

  • a cough with mucus
  • a general feeling of unease
  • difficulty breathing
  • wheezing
  • a runny nose
  • a sore throat
  • fever

Treatment

Acute bronchitis usually clears up within 3 weeks. Treatment focuses on symptom relief as the body fights the virus.

A person can try:

  • getting plenty of rest
  • remaining hydrated
  • using a humidifier
  • using a saline nasal spray
  • inhaling steam
  • taking lozenges

Acute gastroenteritis

Acute gastroenteritis is a common illness. The adenovirus types 40 and 41 can cause this illness.

Some symptoms of acute gastroenteritis include:

  • three or more daily occurrences of loose or watery diarrhea
  • nausea
  • vomiting
  • fever
  • abdominal pain
  • high fever

Treatment

If a person is experiencing gastroenteritis, they need to remain hydrated and replace lost electrolytes.

A person may also wish to take antiemetic medications, such as bismuth subsalicylate.

Adenoviruses are a group of viruses that are transmissible via a variety of methods. The CDC state that the most common ways to transmit these viruses are through:

  • close contact, such as touching or shaking hands
  • coughing and sneezing
  • touching an infected object or surface, then touching the mouth, nose, or eyes without washing the hands first

Adenoviruses can also spread through infected stools — for example, during a diaper change.

Some adenoviruses are contagious in water, especially types 4 and 7. However, this is uncommon, and it usually only happens if there is not enough chlorine in the water.

Sometimes, adenoviruses are transmissible even if a person is not experiencing any symptoms. Catching an adenovirus from a person with no symptoms may be easier if the recipient has a weak immune system.

Doctors can usually diagnose an illness based on the symptoms a person is showing.

However, doctors may order laboratory tests, such as a viral culture, to make sure that there is not a different virus causing the symptoms.

An easy prevention technique is to make sure that both adults and children wash their hands regularly.

Ideally, people should wash their hands:

  • before and after preparing food
  • before eating food
  • before and after touching someone who is vomiting or has diarrhea
  • before and after treating cuts and wounds
  • after using the bathroom
  • after changing a diaper or after helping someone use the bathroom
  • after blowing the nose, coughing, or sneezing
  • after touching an animal, animal food, or animal waste, such as dirty cat litter
  • after touching any garbage

Learn how to properly wash the hands here.

Also, people should not share towels or pillows if they have conjunctivitis. This is to prevent spreading the adenovirus among members of the same household.

Complications from adenoviruses can include acute respiratory distress syndrome (which can develop from viral pneumonia) and viral meningitis (which refers to inflammation of the brain and spinal cord).

According to one 2018 article in the journal Biomedicines, several groups of people have a higher chance of experiencing complications and hospitalization due to adenovirus-related illnesses.

These include people who:

  • have undergone a stem cell or organ transplant
  • have severe combined immunodeficiency syndrome, which are a group of rare, inheritable disorders
  • have HIV
  • have undergone chemotherapy
  • have undergone bone marrow transplants

A person should see a doctor if they believe that they are experiencing symptoms of an adenovirus-related illness and home treatments are not working.

For example, it is important to seek medical advice if:

  • a fever continues for longer than a few days
  • the symptoms worsen
  • it starts to become difficult to breathe
  • it starts to become difficult to consume fluids
  • the person already has a serious illness or weakened immune system

Human adenoviruses are viruses that can cause various symptoms.

They are contagious, and they spread through both direct and indirect contact.

Although people can experience different symptoms and illnesses from different types of adenovirus, the symptoms themselves are usually mild, and people can typically treat them at home.

However, a person should seek medical advice if the symptoms do not go away, or if it becomes difficult to breathe or consume fluids.

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