Adenovirus outbreaks are not very common in the United States, however, they do occur and since the virus is capable of spreading very fast, the outbreaks may achieve large proportions before being contained.
Respiratory tract infections and conjunctiva infections with adenovirus are seen. The commonest time of an outbreak of adenovirus infection is during late winter, spring, and early summer, but infections may occur all year round.
Adenovirus types commonly linked to acute respiratory infections
Adenovirus types that are commonly linked to the outbreaks are those that are more virulent and likely to spread.
These include Adenovirus types 3, 4 and 7 that commonly lead to acute respiratory infections. These may spread widely among populations within a few weeks.
The spread is common via droplets of water that are coughed or sneezed out by an infected person. These droplets are tiny, nearly invisible to the naked eye and carry the virus particle. These are then inhaled by healthy persons.
Spread is more common among those living in close quarters including schools, prisons, hostels, barracks etc. One of the strains, adenovirus type 14, has been particularly associated with several outbreaks of acute respiratory illness among U.S. military recruits and the general public since 2007.
Adenovirus types commonly linked to conjunctival infections
Adenovirus types 8, 19, 37, 53 and 54 are more likely to cause conjunctival infections leading to severe redness, pain and watering of the outer membrane that lies like a film over the eyes.
Adenovirus infection of the conjunctiva is termed adenoviral keratoconjunctivitis. Conjunctivitis due to adenovirus may spread to large populations like an epidemic in a very short period of time.
It is also spread by persistence of the virus in the objects used by an infected person. For example, when an infected person touches a surface with his or her hands that have touched his or her eyes and have not been washed adequately, he or she leaves the virus on the object. This when touched by another healthy person can be picked up.
Adenovirus types commonly linked to gastrointestinal tract infections
Enteric adenovirus types 40 and 41 are known to cause gastrointestinal tract infections especially among children.
Adenovirus infection among swimmers
Adenovirus 4 and 7 can spread in water of swimming pools that have not been chlorinated adequately. This can cause conjunctivitis among swimmers.
Further Reading
Trained immunity: its role in COVID-19 and potential in preparing for future infectious outbreaks