In October 2021, doctors in the United States and the United Kingdom began reporting cases of “mystery” hepatitis (liver inflammation) in children. By late May, roughly 500 children in more than 20 countries had been identified with symptoms of hepatitis of unknown origin.

Hepatitis can have many causes, from viral to toxicological. None of these hundreds of children have tested positive for hepatitis viruses A, B, C, D, or E; however, some of the children have tested positive for adenoviruses. Specifically, adenovirus type 41 has been identified in several cases.

The Press spoke with Dr. Philip Tierno, a clinical professor of pathology at the New York University Grossman School of Medicine, about this emerging epidemiological concern. Adenoviruses are, he said, notoriously difficult to culture, and challenging to type. Therefore, adenovirus 41 may have been present even in the many cases where it has not been identified. Also, adenoviruses are known to cause a variety of symptoms, including hepatitis.

Parents of young children may be concerned that they will contract adenovirus 41, particularly in institutional settings like daycares and preschools. Dr. Tierno says adenoviruses use multiple avenues of infection.

“[They] can be spread by direct contact, indirect contact, and the fecal-oral route, especially by droplets and by contaminated fomites [objects carrying pathogens].” He notes that handwashing is important, and that simply not touching one’s eyes, nose and mouth can reduce the chances of becoming sick.

Two ways to reduce airborne pathogens in ambient air are tuning HVAC systems to provide good ventilation –continuously bringing in fresh air from outdoors – and sanitizing the air in HVAC lines. The latter can be done with ultraviolet (UV-C) rays, or via bipolar ionization. Bipolar ionization releases positive and negative oxygen ions into the air; these ions bond with bacterial and viral particles in ambient air and either inactivate them or allow them to be carried out of living spaces through HVAC systems.

The Environmental Protection Agency (EPA) warns consumers that not all bipolar ionization devices are equal; these devices can create levels of ozone in indoor air that exacerbate asthma and other health conditions. EPA recommends using a device that meets UL 2998 standard certification (Environmental Claim Validation Procedure, or ECVP, for Zero Ozone Emissions from Air Cleaners).

Pathogens are spread via indirect contact when a person touches a contaminated surface before touching his eyes, noes or mouth. Regarding surface disinfection, Dr. Tierno notes that “you must use the proper agent” to kill any particular pathogen on a surface. For example, adenoviruses are difficult to kill, in part because they have no outer envelope. SARS-CoV-2, on the other hand, has an outer envelope that can be disrupted with soap, inactivating the virus. Many chemicals used in surface disinfection also have residual activity that – for a period of time – kills new pathogens that land on that surface, or renders the surface inhospitable to germs.

Industrial hygiene company Enviro-Master has begun offering childcare providers a surface disinfection service to mitigate the indirect contact avenue of infection. The company uses a combination of two products to decontaminate surfaces. One is VitalOxide, made by Vital Solutions, LLC; it is a mixture of chlorine dioxide and quaternary ammonium compounds. Data provided by a company representative indicate that after being sprayed on a surface, provided the product remains wet for five minutes, it will kill adenoviruses. (Ten minutes of wet product will kill mold fungi on surfaces.) The ingredients in VitalOxide provide residual disinfecting activity, but only against bacteria.

The other solution Enviro-Master uses for surface disinfection is Sani-Shield, produced by Unelko Corporation. According to Unelko, Sani-Shield is a mixture of hydrogen peroxide and organosilane quaternary coatings. These coating chemicals make surfaces less receptive to germs by “reduc[ing] the adhesion and build-up of dirt, grime, foodstuff,” and other materials.