Adenovirus infections might not always make headlines, but they’re more common than you might think—and they can affect anyone, including adults. Adenoviruses are a group of viruses that can cause a wide range of illnesses, from respiratory and gastrointestinal problems to eye infections. According to SA Health, while these infections are typically more common during the late winter, spring, and early summer months, they can occur year-round.

Adenovirus infections are particularly prevalent in children, responsible for up to 5% of febrile illnesses—those that cause a fever. Interestingly, these viruses are also known for causing a significant number of asymptomatic infections, meaning many people can carry and spread the virus without even knowing they’re infected. This makes it all the more important to understand the symptoms and treatment options for adenovirus, so you can take the necessary steps to protect yourself and others.

What is Adenovirus?

Adenovirus is a group of viruses that can cause a wide range of infections, affecting the respiratory system, digestive system, eyes, and even the urinary tract. Although adenoviruses are most commonly associated with respiratory illnesses, such as the common cold, they can also cause gastrointestinal issues, conjunctivitis (pink eye), and, in some cases, more severe conditions like pneumonia or cystitis (bladder infection). These viruses are highly contagious and can be spread through respiratory droplets, close personal contact, or by touching contaminated surfaces.

Types of Adenovirus

Adenoviruses belong to a large family of viruses, with more than 100 different serologically distinct types identified so far. However, there are currently around 50 of these types are known to infect humans. These various types can cause a range of illnesses, from mild respiratory infections to more severe conditions, depending on the specific strain.

Among the human-infecting types, adenoviruses are categorised based on the type of illness they cause and the part of the body they affect. For instance, types 1, 2, 3, 4, 5, and 7 are most commonly associated with respiratory illnesses, such as the common cold, sore throat, and even pneumonia. Other types may lead to gastrointestinal issues (like diarrhoea), eye infections (such as conjunctivitis), or urinary tract infections.

Because there are so many different strains of adenovirus, the severity of the infection can vary. In most cases, adenovirus infections are mild and self-limiting, but in certain individuals, such as young children, the elderly, or those with weakened immune systems, the infection can become more serious and may require medical attention.

Who is most at risk?

While adenovirus infections can affect anyone, certain groups are more susceptible to severe symptoms or complications:

Young children: Children under five years old are especially vulnerable to respiratory adenovirus infections, which can lead to more serious conditions like pneumonia or bronchiolitis.
Elderly individuals: Older adults, especially those with underlying health conditions, may face a higher risk of complications.
People with weakened immune systems: Those undergoing chemotherapy, organ transplant recipients, or individuals with immune deficiencies may be at a higher risk for more severe infections and longer recovery times.

Despite this, the majority of adenovirus infections in otherwise healthy individuals tend to resolve on their own without the need for medical intervention.

Common symptoms of Adenovirus

Adenovirus infections can present a wide range of symptoms, depending on the strain of the virus and the part of the body it affects.

Respiratory symptoms

Adenovirus is most commonly linked to respiratory illnesses, and symptoms typically resemble those of the common cold or flu. Some common respiratory symptoms of adenovirus include:

Sore throat: A scratchy or painful throat, often accompanied by difficulty swallowing.
Runny nose or nasal congestion: Similar to cold-like and RSV symptoms, this can cause nasal blockage or a continuous flow of mucus.
Cough: A dry or productive cough, which may worsen over time and become persistent.
Fever: A high temperature is a common symptom and may last for a few days.
Shortness of breath or wheezing: In more severe cases, adenovirus can lead to pneumonia or bronchitis, causing difficulty breathing.
Chest pain or discomfort: This may occur when the virus causes inflammation of the lungs or airways.

These respiratory symptoms can range from mild to more severe, with some individuals developing pneumonia or bronchitis, especially in high-risk groups.

Gastrointestinal symptoms

Adenoviruses can also cause gastrointestinal distress, particularly in children. Common gastrointestinal symptoms include:

Diarrhoea: Adenovirus is a common cause of viral gastroenteritis, leading to frequent, watery stools.
Vomiting: This can occur alongside diarrhoea and may contribute to dehydration.
Abdominal pain or cramping: Discomfort or bloating in the stomach area can accompany the other digestive symptoms.
Loss of appetite: As with many viral infections, a reduced appetite is a common symptom due to gastrointestinal distress.

While these symptoms often resolve within a few days, dehydration can be a concern, especially for young children or the elderly, who may need additional fluids to maintain hydration.

Eye infections (Conjunctivitis)

Adenovirus is a well-known cause of conjunctivitis, commonly referred to as pink eye. Symptoms of adenovirus-related eye infections include:

Redness: The white part of the eye becomes inflamed and red.
Itchy or gritty feeling: The eyes may feel uncomfortable, as though there is something in them.
Watery eyes: Increased tear production is common, often accompanied by discharge.
Sensitivity to light: Photophobia, or increased sensitivity to light, may occur along with other symptoms.

Urinary tract infections

In rare cases, adenovirus can cause urinary tract infections (UTIs), particularly in children and individuals with weakened immune systems. Symptoms of an adenovirus-induced UTI can include:

Pain or burning during urination.
Frequent urge to urinate.
Lower abdominal pain or discomfort.

General symptoms

In addition to the specific symptoms mentioned above, adenovirus infections can cause a range of general symptoms that affect the body as a whole, such as:

Fatigue or tiredness: The body expends energy fighting off the infection, leading to fatigue and a general sense of unwellness.
Muscle aches: Like many viral infections, muscle soreness or aches can accompany adenovirus infections, especially when fever is present.
Headaches: Headaches are common with viral infections like adenovirus, often related to fever and sinus congestion.

When to seek medical attention

While many adenovirus infections resolve on their own, it’s important to seek medical attention if you or someone you know experiences severe symptoms, such as:

Difficulty breathing or shortness of breath.
Severe chest pain.
Persistent high fever or fever that lasts for more than a few days.
Dehydration (e.g., not urinating, dry mouth, dizziness).
Worsening symptoms or complications, such as persistent coughing or stomach pain.

How long is Adenovirus contagious?

Adenovirus is highly contagious, which is one of the reasons it spreads so easily, especially in places where people are in close contact.

The contagion period

Adenovirus can be transmitted from person to person through several routes, including:

Respiratory droplets: When an infected person coughs, sneezes, or talks, the virus can spread through droplets in the air, which can be inhaled by others.
Direct contact: Touching an infected person, like shaking hands or hugging, can transfer the virus.
Contaminated surfaces: Adenovirus can live on surfaces like doorknobs, countertops, and toys for several hours, meaning that touching these surfaces and then touching your face (mouth, nose, or eyes) can lead to infection.

The virus remains contagious as long as symptoms are present, particularly when there is coughing, sneezing, or eye discharge. This means that individuals with an active infection can spread the virus to others from the time their symptoms begin until they resolve.

How long does Adenovirus remain contagious?

Adenovirus is typically contagious for the duration of the symptoms, which can range from a few days to one or two weeks. The virus can remain in the body for a period of time even after symptoms subside, especially in the respiratory system. In some cases, adenovirus can be spread for up to two weeks after the onset of symptoms, particularly if the infection involves the respiratory tract or eyes.

For respiratory symptoms: Individuals with adenovirus can remain contagious for up to two weeks, especially if they are coughing or sneezing.
For eye infections (conjunctivitis): If an individual is suffering from an eye infection caused by adenovirus, they may remain contagious until the redness and discharge have cleared up.
For gastrointestinal infections: People with gastrointestinal issues, like diarrhoea or vomiting caused by adenovirus, can spread the virus for several days after their symptoms have ended.

The Adenovirus incubation period

The incubation period is the time between exposure to a virus and the onset of symptoms. For adenovirus, this period can vary depending on the strain and the individual’s immune system, but generally, symptoms appear within 2 to 14 days after exposure. This relatively long incubation period means that an individual could have contracted adenovirus but not yet show symptoms, making it possible for them to unknowingly spread the virus to others.

How long is the incubation period?

Typical range: The typical incubation period for adenovirus is anywhere from 2 to 14 days. This means that if you've been exposed to someone with adenovirus, it could take up to two weeks before you start showing symptoms, though symptoms often appear within a week.
Respiratory vs. gastrointestinal symptoms: The incubation period can vary slightly depending on the type of infection. Respiratory symptoms, such as sore throat and cough, usually develop within 3 to 5 days after exposure, while gastrointestinal symptoms, like diarrhoea and vomiting, may appear a bit later, typically within 4 to 7 days.

Because adenovirus can spread even before symptoms show up, it’s possible for an infected person to unknowingly pass the virus to others, making it crucial to practice good hygiene and avoid close contact if you suspect you may have been exposed to someone who is sick.

Factors affecting the incubation period

Several factors can influence the exact timing of the adenovirus incubation period:

Type of adenovirus: Different strains of adenovirus can have slightly different incubation periods. Some strains may cause symptoms to appear sooner, while others might take longer.
Immune system health: A person's immune system plays a significant role in how quickly the virus develops and manifests. Those with stronger immune systems might experience symptoms later, or they may experience milder symptoms, while individuals with weakened immune systems (such as the elderly or those with chronic conditions) may develop symptoms more quickly and experience more severe illness.
Exposure level: The amount of the virus a person is exposed to can also impact the incubation period. For instance, someone who has close, prolonged contact with an infected person may develop symptoms more quickly than someone who has limited exposure.

Treatment options for Adenovirus infection

Adenovirus infections are typically self-limiting, meaning that they usually resolve on their own without the need for extensive medical intervention. However, depending on the severity of the infection and the symptoms, there are various treatment options available to help manage symptoms and improve comfort. While there is no specific antiviral treatment for adenovirus, supportive care and symptom management can go a long way in helping you recover more comfortably.

1. Symptom management

Since adenovirus infections usually cause mild to moderate symptoms, treatment is often focused on alleviating these symptoms and providing relief. Common symptoms such as fever, sore throat, coughing, and gastrointestinal discomfort can be managed with over-the-counter (OTC) medications and home remedies.

Fever and pain relief: Non-prescription pain relievers such as paracetamol (acetaminophen) or ibuprofen can help reduce fever and ease body aches. These medications can also alleviate headaches and general discomfort associated with the infection. Always follow dosing instructions carefully and avoid giving aspirin to children or teenagers due to the risk of Reye’s syndrome.
Hydration: If you are experiencing fever, diarrhoea, or vomiting, staying hydrated is important. Drink plenty of fluids like water, herbal teas, or oral rehydration solutions (especially for those with gastrointestinal symptoms) to prevent dehydration.
Rest: Rest is essential for your body to fight off the virus. Try to get plenty of sleep and avoid strenuous activities to allow your immune system to function optimally.

2. Managing respiratory symptoms

If adenovirus causes respiratory symptoms like a sore throat, cough, or congestion, there are a few treatments you can try to ease the discomfort:

Gargling with salt water: This simple home remedy can help soothe a sore throat and reduce inflammation. Mix 1 teaspoon of salt in a glass of warm water and gargle several times a day.
Cough medicines: Over-the-counter cough syrups or lozenges can help relieve a dry or sore throat, though they are generally not recommended for children under 6 years old. Choose cough suppressants if you're having trouble sleeping due to coughing, or expectorants if you have a productive cough and need help loosening mucus.
Humidifiers: Using a humidifier in your bedroom can help keep the air moist, which may ease coughing, sore throats, and nasal congestion.

3. Treating gastrointestinal symptoms

For those suffering from gastrointestinal symptoms, such as diarrhoea, vomiting, and abdominal pain, treatment primarily focuses on staying hydrated and managing discomfort.

Oral rehydration solutions: These are key for replenishing lost fluids and electrolytes. They are especially important for children and the elderly, who are more susceptible to dehydration.
Anti-diarrhoeal medication: While over-the-counter anti-diarrhoeal medications like loperamide can be used to control diarrhoea, they are generally not recommended for children or for people with fever, as diarrhoea is often a way for the body to clear the virus. It is best to let the body resolve the symptoms naturally while maintaining hydration.
Bland diet: Stick to a bland diet while experiencing gastrointestinal issues, such as the BRAT diet (bananas, rice, applesauce, and toast), which can help ease stomach discomfort.

4. Eye infections (Conjunctivitis)

If adenovirus causes eye infections, also known as conjunctivitis or pink eye, it can be quite uncomfortable but typically resolves on its own within 1-2 weeks. However, the following treatments can help alleviate the symptoms:

Warm compress: Applying a warm compress to the affected eye can help relieve discomfort and reduce swelling. Clean your hands thoroughly before touching your face or eyes to avoid further irritation.
Artificial tears: Over-the-counter lubricating eye drops can help soothe the eyes and reduce irritation or dryness caused by conjunctivitis.
Avoid touching the eyes: Since adenovirus is highly contagious, avoid rubbing or touching your eyes, and wash your hands frequently. Do not share towels or eye makeup, and disinfect surfaces you frequently touch.

When you should seek professional help

Severe respiratory symptoms

If you experience severe difficulty breathing, wheezing, chest pain, or persistent high fever, seek medical attention immediately. These could be signs of complications like pneumonia or bronchitis.

Prolonged symptoms

If symptoms persist for more than two weeks or worsen over time, it may indicate that you have developed a secondary infection or other complications that require medical treatment.

Signs of dehydration

If you or someone you are caring for is unable to keep fluids down, shows signs of dehydration (such as dry mouth, dizziness, or little to no urination), it’s important to consult a healthcare provider.

Weakened immune system

Individuals with weakened immune systems, such as those undergoing chemotherapy, organ transplant recipients, or people with HIV, should seek medical care as soon as symptoms appear. Adenovirus can cause more severe infections in these individuals.

How to know if you’re having Adenovirus

Adenovirus can present symptoms very similar to those of the common cold, flu, or respiratory syncytial virus (RSV), making it difficult to pinpoint exactly which infection you may have without proper testing. Because adenovirus is highly contagious, it's essential to isolate yourself as much as possible to prevent spreading the virus to others, especially in places like schools, workplaces, or crowded environments.

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Conclusion

Practising good hygiene, such as frequent hand washing and avoiding close contact with infected individuals, is key to preventing the spread of adenovirus, particularly during outbreaks.

While adenovirus infections are common, they are typically not serious for most healthy individuals. If symptoms persist or worsen, however, don't hesitate to seek medical advice to ensure the best possible care and recovery.

April 10 2025, by Tatianna Gerard What is Adenovirus (AdV)? Learn About Its Impact, Symptoms & How to Treat It