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

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.

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Human adenoviruses are viruses that cause infections in the:

They are a common cause of upper respiratory infections and conjunctivitis.

Types of adenovirus

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

There are a number of different adenoviruses that can cause 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 CDC states that adenoviruses can affect people of all ages.

They are often present in places where people live in close contact or come into close contact with others, such as:

  • military barracks
  • public swimming pools
  • daycare centers
  • households with young children
  • medical facilities

This is because the viruses usually spread by droplets in the air.

Most cases are asymptomatic or cause mild cold- or flu-like symptoms.

However, adenoviruses can cause a wide range of symptoms depending on the organs affected. For example, a person may experience symptoms associated with:

How long can adenovirus symptoms last?

The length of time symptoms can last depends on the illness it has caused. For example:

  • Gastroenteritis usually lasts for 2 to 3 days.
  • Conjunctivitis can take 7 days to 3 weeks to recover.
  • Symptoms of cystitis can persist for a few days to 2 weeks, but usually lasts for 5 days
  • Symptoms of pneumonia can persist for 2 to 4 weeks.

The CDC states that adenoviruses can spread 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 stool — for example, during a diaper change.

Some adenoviruses, especially types 4 and 7, are contagious in water. However, this is uncommon and 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. Contracting 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 ensure that a different virus is not 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

Also, people should not share towels or pillows if they have conjunctivitis. This helps prevent the spread of 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 (inflammation of the brain and spinal cord).

Those at a higher risk of severe illness include those with existing respiratory illness or heart conditions, and those with weakened immune systems.

There are no approved antiviral medications to treat an adenovirus infection. There is also no specific treatment.

A person can treat most cases at home with rest, over-the-counter pain medications, and medications to reduce fever.

However, a person should contact a healthcare professional 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 contagious viruses that can cause various symptoms. They spread through 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.