What is adenovirus

Adenoviruses are common viruses that cause a range of illness. Adenoviruses can cause cold-like symptoms, sore throat, bronchitis, pneumonia, diarrhea, and pink eye (conjunctivitis). You can get an adenovirus infection at any age. People with weakened immune systems or existing respiratory or cardiac disease are more likely than others to get very sick from an adenovirus infection. Some people infected with adenoviruses, especially those who have weakened immune systems, can have ongoing infections in their tonsils, adenoids, and intestines that do not cause symptoms. They can shed the virus for weeks or longer.

Adenovirus can survive for extended periods on environmental surfaces and is resistant to lipid disinfectants because it is nonenveloped, however, it is inactivated by heat, formaldehyde, and bleach ¹. Adenoviruses are relatively resistant to common disinfectants and can be detected on surfaces, such as doorknobs, objects, and water of swimming pools and small lakes.

Also, adenoviruses have historically been a common cause of acute respiratory illness in military recruits, although the frequency has significantly decreased since the reinstitution in March 2011 of the adenovirus vaccine administration.

Adenoviruses are very common and come in many types. Depending on the virus type, adenoviruses can cause:

• respiratory (breathing) problems that can include cough, fever, and runny nose
• headache
• sore throat
• eye infections

These symptoms can last up to 10 days.

Infection with adenovirus can also rarely lead to more serious problems, such as pneumonia, stomach and bowel problems, and even death. Some people who are infected may have to be hospitalized.

Adenovirus infection can be spread from person to person through the air (for example, by sneezing or coughing). It can also be spread by personal contact, such as touching an infected person or handling objects that an infected person has touched.

Two types of adenovirus (Type 4 and Type 7) have caused severe outbreaks of respiratory illness among military recruits.

Adenoviruses usually spread from infected people to others through:

• close personal contact such as touching or shaking hands
• the air by coughing and sneezing
• touching an object or surface with adenoviruses on it, then touching your mouth, nose, or eyes before washing your hands

Some adenoviruses can spread through an infected person’s stool, for example, during diaper changing. Adenovirus can also spread through the water, such as swimming pools, but this is less common.

Sometimes adenovirus can be shed (released from the body) for a long time after a person recovers from an adenovirus infection, especially among people who have weakened immune systems. This “virus shedding” usually occurs without any symptoms, even though the person can still spread adenovirus to other people.

There is no specific treatment for people with adenovirus infection. Most adenovirus infections are mild and may require only care to help relieve symptoms.

Adenoviruses are medium-sized (90-100 nm), non-enveloped icosohedral viruses with double-stranded DNA. Adenoviruses were first discovered in 1953, by Rowe and his colleagues ². Adenoviruses were first isolated from adenoid cell culture, hence the family name of Adenoviridae. Over 60 human adenovirus ³ serotypes have been identified based on antigenic determinants detected by viral neutralization assays and hemagglutination studies. And more than 50 types of immunologically distinct adenoviruses can cause infections in humans. In 1962, Trentin and colleagues made the important discovery that adenovirus 12 could induce tumors in hamsters in a laboratory setting. Since this discovery, adenoviruses have been suspected in inducing human cancers but have not been proven to definitively cause cancer in humans. Experiments involving adenoviruses have also made important contributions to molecular biology. Most importantly, adenoviruses have helped scientist to understand messenger RNA splicing. By studying the mRNA produced by adenoviruses, scientists have realized that there were introns imbedded into these transcripts.

Figure 1. Adenovirus

[Source ²]

Adenovirus symptoms

Adenoviruses are ubiquitous, double-stranded DNA viruses that are most commonly associated with pediatric illnesses of the upper respiratory tract. The illnesses can range from the common cold to pneumonia, croup, and bronchitis. Depending on the type, adenoviruses can cause other illnesses such as gastroenteritis, conjunctivitis, cystitis, and, less commonly, neurological disease.

Adenoviruses can cause a wide range of illnesses such as:

• Common cold
• Sore throat
• Bronchitis (a condition that occurs when the airways in the lungs become filled with mucus and may spasm, which causes a person to cough and have shortness of breath)
• Pneumonia (infection of the lungs)
• Diarrhea
• Pink eye (conjunctivitis)
• Fever
• Bladder inflammation or infection
• Inflammation of stomach and intestines
• Neurologic disease (conditions that affect the brain and spinal cord)

Adenoviruses can cause mild to severe illness, though serious illness is less common. People with weakened immune systems, or existing respiratory or cardiac disease, are at higher risk of developing severe illness from an adenovirus infection.

Adenovirus diagnosis

Adenovirus infections can be identified using antigen detection, polymerase chain reaction (PCR), virus isolation, and serology. Adenovirus typing is usually done by molecular methods.

Even if a person has adenovirus infection, it does not necessarily mean it is causing the person’s particular illness. Some people, especially those who have weakened immune systems, can shed the virus for weeks or longer and not have symptoms.

Health professionals should:

• consider adenoviruses as possible causes of upper respiratory infection, lower respiratory infection such as pneumonia, and conjunctivitis (individual cases or outbreaks)
• report unusual clusters (e.g., respiratory, conjunctivitis) caused by adenoviruses to the state or local health department

Specimen Collection and Laboratory Testing

Specimen Collection

The types of specimens you should collect for human adenovirus detection depend on the patient’s clinical presentation and type of infection. Before collecting any specimens, discuss with a laboratory and a clinician familiar with adenovirus. To improve human adenovirus detection, you should collect specimens within a week of symptom onset.

• Respiratory Infections. For respiratory infections, you should typically collect upper respiratory specimens such as a nasopharyngeal swab and/or oropharyngeal (throat) swab. If there is evidence of a lower respiratory infection, you should also collect a lower respiratory specimen such as sputum. In some instances, a serum specimen may be helpful.
• Eye Infections. If there is clinical evidence of a conjunctival or eye infection, you should collect a conjunctival swab.

Laboratory Testing

Many laboratories can test for human adenoviruses, but the extent of testing capability can vary. If specialized testing is needed, contact your state health department to discuss available testing options. Additional information on adenovirus testing at Centers for Disease Control and Prevention (CDC) is available at Submitting Specimens to CDC.

Laboratories can detect and type human adenoviruses using:

• Molecular detection (e.g. PCR)
• Partial or full genome sequencing
• Antigen detection
• Virus isolation
• Virus neutralization with type-specific antisera

Adenovirus prevention

Follow simple steps to protect yourself and others

You can protect yourself and others from adenoviruses and other respiratory illnesses by following a few simple steps:

• Wash your hands often with soap and water
• Avoid touching your eyes, nose, or mouth with unwashed hands
• Avoid close contact with people who are sick

If you’re sick you can help protect others:

• Stay home when you are sick
• Cover your mouth and nose when coughing or sneezing
• Avoid sharing cups and eating utensils with others
• Refrain from kissing others
• Wash your hands often with soap and water, especially after using the bathroom

Frequent handwashing is especially important in childcare settings and healthcare facilities.

Maintain proper chlorine levels to prevent outbreaks

Adenoviruses are resistant to many common disinfectant products and can remain infectious for long periods on surfaces and objects. It is important to keep adequate levels of chlorine in swimming pools to prevent outbreaks of conjunctivitis caused by adenoviruses.

Adenovirus vaccine is for U.S. military only

There is currently no adenovirus vaccine available to the general public.

A vaccine specific for adenovirus types 4 and 7 was approved by the U.S. Food and Drug Administration in March 2011, for use only in U.S. military personnel who may be at higher risk for infection from these two adenovirus types.

Adenovirus vaccine

Currently, there is no adenovirus vaccine available for the general public. Adenovirus vaccine contains live adenovirus Type 4 and Type 7 ⁴. It will prevent most illness caused by these two virus types.

Adenovirus vaccine comes as two tablets, taken orally (by mouth) at the same time. The tablets should be swallowed whole, not chewed or crushed.

Adenovirus vaccine may be given at the same time as other vaccines.

Who should get adenovirus vaccine?

The vaccine is approved for military personnel 17 through 50 years of age ⁴. It is recommended by the Department of Defense for military recruits entering basic training. It may also be recommended for other military personnel at high risk for adenovirus infection.

Precautions

Some people should NOT get adenovirus vaccine:

• Anyone with a severe (life-threatening) allergy to any component of the vaccine. Tell the doctor if you have any severe allergies.
• Pregnant women or nursing mothers.
• Anyone who is unable to swallow the vaccine tablets whole without chewing them.
• Anyone younger than 17 or older than 50 years of age.

Other precautions:

• Talk with a doctor if:
  • you have HIV/AIDS or another disease that affects the immune system, or
  • your immune system is weakened because of cancer or other medical conditions, a transplant, or radiation or drug treatment (such as steroids or cancer chemotherapy).
• Women should not become pregnant for 6 weeks following vaccination.
• Vaccination should be postponed for anyone with vomiting or diarrhea.
• Virus from the vaccine can be shed in the stool for up to 28 days after vaccination. To minimize the risk of spreading vaccine virus to other people during this period, observe proper personal hygiene, such as frequent hand washing, especially following bowel movements. This is especially important if you have close contact with children 7 years of age and younger, with anyone having a weakened immune system, or with pregnant women.

What are the risks from adenovirus vaccine?

A vaccine, like any medicine, could cause a serious reaction. But the risk of a vaccine causing serious harm, or death, is extremely small.

Mild Problems

Several mild problems have been reported within 2 weeks of getting the vaccine:

• headaches, upper respiratory tract infection (about 1 person in 3)
• stuffy nose, sore throat, joint pain (about 1 person in 6)
• abdominal pain, cough, nausea (about 1 person in 7)
• diarrhea (about 1 person in 10)
• fever (about 1 person in 100)

Serious Problems

More serious problems have been reported by about 1 person in 100, within 6 months of vaccination. These problems included:

• blood in the urine or stool
• pneumonia
• inflammation of the stomach or intestines

It is not clear whether these mild or serious problems were caused by the vaccine or occurred after vaccination by chance.

As with all vaccines, adenovirus vaccine will continue to be monitored for unexpected or severe problems.

Adenovirus treatment

There is no specific treatment for people with adenovirus infection. Most adenovirus infections are mild and don’t require any medical care; clinical care of adenovirus infections includes supportive management of symptoms and complications. Cidofovir has been used to treat severe adenovirus infections in people with immunocompromised systems in specific situations.

References

1. Khanal S, Ghimire P, Dhamoon AS. The Repertoire of Adenovirus in Human Disease: The Innocuous to the Deadly. Biomedicines. 2018;6(1):30. doi:10.3390/biomedicines6010030. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874687/
2. History of Adenoviridae. https://web.stanford.edu/group/virus/adeno/2004takahashi/webpage/second.html
3. Identification and typing of respiratory adenoviruses in Guangzhou, Southern China using a rapid and simple method. Han G, Niu H, Zhao S, Zhu B, Wang C, Liu Y, Zhang M, Yang S, Liu F, Wan C, Zhang Q. Virol Sin. 2013 Apr; 28(2):103-8.
4. Adenovirus VIS. https://www.cdc.gov/vaccines/hcp/vis/vis-statements/adenovirus.html