With the fear and frenzy of Ebola, one virus that has infected nearly 600 (mostly children) and infiltrated 43 states (plus Washington, D.C.) has been getting less attention: Enterovirus D68. And it has been confirmed that Enterovirus is directly responsible for the death of a 4-year-old in Hamilton, N.J., according to CNN's Anderson Cooper.

Eli Waller, the smallest triplet among his siblings, reportedly seemed OK when he went to sleep Sept. 24, but he never woke up, according to ABC News. Enterovirus is known to move quickly, and the 4-year-old went from cold symptoms to breathing troubles within three days. Children, with their immature immune systems, are more susceptible to the virus and children with pulmonary issues are even more at risk.

Andy Waller, Eli's dad, released a letter on Sunday evening, according to ABC News. Waller stated that Eli's siblings are not exhibiting any symptoms and compared his son who just started preschool to "a shy little puppy who wants only to make people proud and happy, maybe tripping a bit over his own paws, but truly full of unconditional love."

The Waller family was reportedly starting The First Day of School Foundation which would provide support for special education students.

"Like so many kids his age, Eli was both nervous and excited about starting school, and it is our sincere hope that this Foundation can work to help kids in a way that will make Eli proud of us all, in the same way that we were all so proud of him," Eli's dad was quoted as saying.

As of 8 p. m. EST, Eli's sisters are awaiting results of their Enterovirus testing.

Hamilton Health official: Eli Waller's sisters being tested for EV-D68. Samples at CDC now. — Sabina Kuriakose (@SabinaKuriakose) October 7, 2014

Tabitha Vassey, the mother of Eli's best friend is watching her son struggle to fight off the virus, according to another ABC article. Vassey said her son hasn't quite grasped that he won't see his best bud again. "My son is still saying, 'When I get better, I'm going back to see Eli. We're going to have a party. We're going to play on the jungle gym,'" Vassey is quoted as saying. "I'm sitting here trying to tell him he's not going to come back ... in a kid way he's going to understand."

CNN's Anderson Cooper spoke to Dr. Sanjay Gupta, CNN's senior medical correspondent, about Enterovirus and why it is so dangerous for children.

According to the Washington Post, "Enterovirus is the name used to describe a group of more than 100 of the most common viruses that affect humans and other mammals. Most people might interact with an enterovirus by way of the common cold, which can be caused by enteroviruses as well as rhinoviruses."

Enteroviruses are airborne, so they spread through coughing or sneezing, and with young children just starting school, their immune systems aren't quite equipped to fight off disease as well as older students.

Parents are told to watch out for difficulty breathing in their child, especially a child with asthma or other compromising respiratory conditions. The virus can be halted by following usual hygiene: wash your hands, cover your mouth with you sneeze, don't touch your nose or mouth and if you feel sick, stay home from school or work.