Adenovirus infections are usually mild, but can cause symptoms such as cough, fever, ear infection, conjunctivitis or gastroenteritis, more rarely hepatitis. How is the transmission done? What treatment? Answers from Dr. Fabienne Kochert, pediatrician.
Adenoviruses infect especially young children. They mainly cause infections benignwith some peaks epidemic in winter and spring. In the immunocompromised person, the infection can be severe. In infants, it may be responsible for bronchiolitis and of pneumonia. In April 2022, a mysterious outbreak of acute hepatitis has been observed in young children in Europe (including France) and in the United States. Faced with this strange increase in cases, the WHO has published a report advancing an adenovirus infection as possible cause. Adenovirus (type 41) has been identified in faecal samples from almost half of infected children. “Although adenovirus is currently hypothesized as the underlying cause, it does not fully explain the severity of the clinical picture“, indicates the organization. How do you catch the adenovirus? What symptoms does he train? How is the diagnostic ? How treat an adenovirus infection ? Insight from Dr Fabienne Kochert, pediatrician and President of theFrench Association of Ambulatory Pediatrics (AFPA)).
Definition: what is an adenovirus?
“Adenovirus is a virus widespread but which is not talked about as much as the flu, bronchiolitis or Covid-19 virus for example, insofar as it causes rather mild infections“, asks Dr. Fabienne Kochert from the outset. Viruses have a DNA or RNA genome, which classifies them in two distinct categories.
► Theadenovirus (which belongs to the Adenoviridae family) is a DNA virus (without envelope, see diagram below), i.e. its genome – all of its genetic material – is made up of DNA.
► The flu virus or the Covid virus are RNA viruses, that is to say that their genome consists of an RNA. RNA viruses have higher mutation rates than DNA viruses.
“Transmission of an adenovirus is by direct contact or more rarely by hand (via hands in contact with a contaminated object or food) with nasopharyngeal secretions (saliva, respiratory droplets…) or the stool of an infected person”, explains the pediatrician. Viral transmission is facilitated by community life, enclosed spaces, poorly ventilated and occurs more readily in specific communities such as nurseries, schools, daycare centers, barracks or swimming pools. And as with all viruses, adenovirus infections can also be nosocomialthat is to say, contracted during a stay in a health establishment (hospital, clinic, etc.).
The transmission of an adenovirus can be easily done from one person to another.
Is adenovirus contagious?
Yes. The transmission of an adenovirus can be done easily from one person to another through the air. In addition, adenoviruses are very resistant in the environment and can persist for several weeks on surfaces. Their contagiousness is therefore high. Transmission between members of the same household (parents-children) is frequent.
What is the incubation period of an adenovirus?
The incubation period of an adenovirus extends from 2 to 14 days.
No clinical picture is specific to adenovirus.
What symptoms cause an adenovirus?
As with all respiratory viruses, the symptoms are not very suggestive. No clinical picture is specific to adenovirus. In immunocompetent patients as in adults (immunocompetence is the body’s ability to produce a normal immune response, after exposure to an antigen), the infection may be completely asymptomatic. The clinical signswhen they are present, are very varied:
- nasopharyngitis
- angina
- bronchiolitis (in babies)
- otitis
- cough
- fever (moderate intensity)
- eye damage: conjunctivitis or keratoconjunctivitis (corneal damage). “Keratoconjunctivitis is the most typical sign of adenovirus infection, but remains infrequent“specifies our interlocutor.
- digestive disorders (gastroenteritis), with diarrhea, vomiting and abdominal pain.
- hemorrhagic cystitis (rare)
In immunocompromised children and adults (having received an organ transplant, for example), adenovirus infections can be more severe and scatteredwith potential damage to many organs:
- pneumonia
- meningoencephalitis
- hepatitisparticularly severe, potentially and exceptionally fatal
“Usually, there is no indication to search for this virus precisely. With the Covid pandemic, the TRODs (rapid diagnostic orientation tests) have become widespread and make it possible to identify, in the presence of an infectious picture, the type of virus in question (influenza, RSV, adenovirus, etc.)“, describes our interlocutor. As far as the adenovirus is concerned, it can be identified by a PCR (molecular research) from respiratory secretions, a sample of blood, stool, urine… “If we are faced with keratoconjunctivitis, we can do a PCR on a conjunctival sample for example. We can also search for antibodies as for other viruses, but it is of little diagnostic value and only allows retroactive diagnosis after recovery“, specifies the pediatrician. PCRs are generally only useful for people who are fragile, immunocompromised, transplanted or who have a severe form of the infection.
In the vast majority of cases, adenovirus infections resolve spontaneously.
What is the treatment for an adenovirus?
“Treatment is primarily symptomatic : treatment of fever, cough, pain, diarrhea… and we wait for it to heal. The longest to heal is keratoconjunctivitis because the cornea takes a long time to heal“, indicates our interlocutor. In the vast majority of cases, adenovirus infections heal spontaneously. No antiviral is really effective against adenoviruses. “For the flu, an antiviral drug is available (Tamiflu®) which can limit viral replication when given early enough, but nothing has been described for adenoviruses“, she specifies.
Compliance with hygiene precautions is essential to prevent the transmission of adenoviruses:
- Regular hand washing
- Wearing a mask for sick people or in the presence of fragile people
- No close contact with an infected person
- Disinfection of potentially contaminated surfaces and objects because these viruses retain their infectivity for a long time on surfaces.
Is there a vaccine against adenovirus?
An adenovirus vaccine should not be confused with the adenovirus vaccine which refers to a specific protection technology.
There is no adenovirus vaccine for the general population. An oral vaccine has been developed by the US military that is believed to be able to reduce the incidence of adenovirus infections, but it is not available only for military personnel. Please note, you must not not confuse a vaccine against adenovirus with adenovirus vaccines which are vaccines that use an adenovirus that is not pathogenic for humans as a viral vector to immunize the body against another infectious agent, for example Sars-CoV-2. Indeed, adenoviruses (rendered harmless) can be used in vaccination to elicit an immune response. It is in particular the principle of certain anti-Covid vaccines like Vaxzevria from AstraZeneca, the Janssen vaccine from Johnson & Johnson or the Russian vaccine Sputnik V.
Thanks to Dr Fabienne Kochert, pediatrician and president of the French Association of Ambulatory Pediatrics (AFPA)
Source: French Society of Microbiology