The recent death of a University of Maryland freshman from complications of an adenovirus infection brought the virus and the disease it causes into the limelight. According to The Washington Post:
“In a statement, U-Md. said it learned Nov. 1 of what it said was then an “isolated case” of adenovirus. However, the statement, issued by David McBride, head of the campus health center, said that since then five more cases have been reported of students with confirmed adenovirus-associated illness. The student who died was identified by her father, Ian Paregol, as Olivia Paregol, 18, a freshman from Howard County, Md. She lived in a campus dormitory, her father said in an interview. She was “free-spirited and friendly,” he said. “Everybody she came across loved her.” She died Sunday in an intensive care unit at Johns Hopkins Hospital in Baltimore, he said.”
According to the Centers for Disease Control and Prevention (CDC), there are over 50 adenovirus types, all known to cause human infection. Infection with adenoviruses usually presents as an upper respiratory disease, but there are some instances in which the infection presents as a gastroenteric disease (abdominal pain, diarrhea). For most people, the infection clears up in a few days, just like most respiratory ailments do.
Transmission of adenoviruses can be through respiratory droplets, like with any other respiratory infection. It can also be transmitted through contaminated objects and through contact with fecal material from infected persons. In the United States, it is estimated that adenovirus infection outbreaks occur at any time of the year in institutional settings where people are in close proximity to each other, like college dorms, nursing homes, and military barracks.
Adenovirus outbreaks have been a concern for the military dating back to the discovery of the virus (during an outbreak at a military facility in Missouri) in 1953. Since then, several vaccines have been used to prevent those outbreaks, but none of those vaccines have been licensed for use in the general population. Between 1999 and 2011, no vaccine was used as the vaccine manufacturer found it cost-prohibitive to make and distribute the vaccine. During that time, eight deaths in the military from adenovirus disease were identified, while there were only five between 1967 and 1999. Then, in 2011, a new vaccine was licensed and administered to troops. The new vaccine, a live-attenuated vaccine delivered via two tablets that are ingested, has been available to the military since.
The death of Ms. Paregol at the University of Maryland brought with it many questions from many people about the vaccine. Many (in online discussions and comment sections of the news articles about the event) wondered why the vaccine would be available for troops living in close quarters but not college students living in school dormitories. The answer to this may be in the number and severity of cases. Unlike influenza, which kills between 12,000 and 56,000 people in the United States, adenovirus infections don’t seem to kill that many people, and the outbreaks are usually confined to the institutional places where they happen. That is, the outbreaks don’t seem to spread into the community.
Nevertheless, death (mortality) is not the only way to measure the impact of a disease or condition. The number of cases (morbidity) is also a good indicator of how much a disease or condition can affect a population. However, because there is not a good system in place to keep track of adenovirus infections (beyond outbreak investigations), we don’t have a good estimate of how many people contract adenovirus infections, how many of them require medical care, and how many miss work or school because of them.
For the time being, it seems that the vaccine will only be available to the military because it is a national security concern if troops go down with any kind of infection. (Soldiers receive other immunizations that the general public doesn’t receive, like the smallpox vaccine and Anthrax vaccine.) But, as cities get more and more congested, it is possible that these kinds of outbreaks become more common as crowding will be an issue. Instead of a dormitory or a barracks, we may be looking at outbreaks in an apartment building or a large shelter for displaced persons. Public health is going to have to catch up, and we may be adding an additional vaccine to our arsenal for use in the general population.