Adenovirus outbreak kills 6 kids in New Jersey, but what is it? Adenovirus is a common virus that affects the respiratory system.

The New Jersey Department of Health confirmed 18 cases of adenovirus among pediatric residents at the Wanaque Center for Nursing and Rehabilitation in Haskell on Tuesday. Of those children, six have died.

The facility notified the Department of Health of the children having the respiratory virus on Sunday, and the DOH responded by sending an inspection team, which found “minor handwashing deficiencies,” according to a statement from the Department of Health.

The deaths were confirmed on Tuesday after another inspection team was sent to the facility.

The DOH has instructed the facility not to admit any new patients until the outbreak ends and the facility is complying fully, according to the statement.

Adenoviruses are a family of viruses that often cause mild illness, especially in young children. The particular strain of the virus in this outbreak (adenovirus #7) has infected medically fragile children with severely compromised immune systems. This strain in particular has been associated with disease in communal living arrangements and it tends to be more severe.

What is adenovirus?

Adenoviruses are common viruses that cause a range of symptoms, including those associated with the common cold, sore throat, bronchitis, pneumonia, diarrhea, and pink eye. You can get adenovirus at any age, and many of us have had it at one time or another — it presents itself in different forms and is usually more on the mild side.

"There are at least 60 serotypes of adenovirus," Dr. Todd Ellerin, an infectious disease specialist at South Shore Hospital in Massachusetts, told ABC News. "[But] there are only a few types that can cause severe respiratory distress, and #7 is one of them. Rarely does adenovirus get this nasty."

Is adenovirus #7 something we see frequently?

The last big outbreak of adenovirus #7 that we are aware of was in Oregon from October 2013 to July 2014.

During this time, Oregon health authorities identified 198 people with respiratory symptoms who tested positive for adenovirus #7. Among the 136 people who were hospitalized, 31 percent were admitted to the intensive care unit and 18 percent needed mechanical ventilation. Five patients died.

Who does adenovirus impact the most?

People with weakened immune systems or existing respiratory or cardiac disease are more likely than others to get sick from an adenovirus infection.

"It’s more dangerous in children or adults who are immunocompromised. People with T-cell deficiencies like transplant patients are more susceptible," Ellerin said.

But it can also affect people in crowded spaces. Noting that it’s a highly contagious virus, Ellerin mentioned that "there have been fatal cases seen in military recruits in the past because of crowding. They were so close to each other that the respiratory diseases spreaded."

In the case of the children at the Wanaque Center, it’s unclear how the disease spread among the children, except that there were "handwashing deficiencies."

"We understand that the children that died were more susceptible, but we need to know how did it spread," Ellerin said. "Whenever you hear of an outbreak, you need to ask if there was an infection control lapse, which means cleanliness of surfaces. Hand hygiene. We don’t know what happened in this case, but that is what will be looked at."

Ellerin added that the DOH would likely send an infection prevention team, or experts who figure out what happened; an environmental care team, which cleans the area; and a quality improvement team, which works to ensure an outbreak doesn’t happen again.

What is the treatment?

When it comes to treatment, there’s not much we can do — for this severe strain of adenovirus, at least.

"There is not a good treatment for adenovirus like this," Ellerin said. "We don’t have a Tamiflu equivalent for adenovirus. Tamiflu is known to help people who have severe flu and there is no equivalent for adenovirus."

For other strains of adenovirus, however, when you have elevated fever or trouble breathing or shortness of breath, confusion, severe or persistent vomiting, or pain or pressure in the abdomen, get medical attention.

Eric M. Strauss is the managing editor of the ABC News Medical Unit