The adenoviruses are a family of more than fouty viruses, identified by sequential letters and numbers, first found in adenoids(lymphoid tissue at the back of the pharynx) in the early 1950's, but definitely around for a long time before that. There are also adenoviruses that only infect animals. The ones that like people cause about 5 percent of all respiratory illnesses, from mild flulike systems to pneumonia, which are rarely fatal though of special concern among military recruits. Most children around the world have been infected with the more common adenoviruses by the time they reach school age. Some types are known to zero in on older children and adults in swimming pools and lakes.
Outbreaks of untrivial respiratory illnesses in new soldiers caused by the adenovirus have been a recognized problem since at least the Civil War. The term "acute respiratory disease" gained acronym status as ARD during World War II. Up to twenty cases per one hundred recruits could be expected, creating a significant drag on training. Just why some of the adenoviruses enjoy these young men so much compared to civilians, is not clear. Populations of recruits have traditionally been subject to diseases usually seen in childhood, such as chicken pox, mumps, and rubella(German measles), perhaps because of stress, crowding, and the micture of immune and nonimuune bodies from many dirfferent locales. Except during massive mobilizations, troops can be separated into samll units when they first arrive, which helps to avert epidemics. Then again, many f these guys don't mind a few days in sick bay.
THe ability of adenoviruses to infect our tonsil and adenoids for long periods of time implies that they have learned how to outwit our defenses. They do not fall into a latanet state, like herpes viruses, but reproduce constantly at a snail's pace, changeing the cells they enter in such a way that the immune system cnanot tell the difference. Some of their tricks give them the power to produce tumors, but this has been observed only in unnatual hosts such as hamsters. Why adenoviruses cannot cause cancer in people is unknown.