A New Jersey preschooler was being monitored for Enterovirus D68 Sunday after another 4-year-old boy from the same classroom died from the disease last week, authorities said.

The boy, another 4-year-old from an elementary school in Hamilton Township, was out sick on Friday, said Jeffrey Plunkett, the township's health officer. The boy's nasal and throat cultures have been sent to the Centers for Disease Control for testing, he said.

"The school nurses are constantly in touch with our nurses and our health department," Plunkett said. The school district has also increased monitoring for any type of illness, he added.

On Thursday 4-year-old Eli Waller died from the virus, according to Dr. James Parla, the schools' superintendent for Hamilton Township, which is just west of Atlantic City.

Enterovirus D68 causes mild to severe respiratory problems, including fever, a cough and difficulty breathing or wheezing, according to the CDC. It mainly affects children and is spread when someone through coughing, sneezing or touching.

There were 538 confirmed cases of the virus from 43 states and the District of Columbia, including New York and New Jersey, as of Friday, according to the CDC.

Eli was the only boy in a set of triplets, Plunkett said. His parents have been holding up remarkably well, he said.

"It's the most traumatic experience any of us could experience," he said. "Their biggest concern is Eli's two sisters and getting them reacclimated into the community on an everyday basis."

The newly sick boy and Eli shared a classroom: one had morning classes and one had afternoon classes, Plunkett said.

There are about 20 children in the classroom, he said, and about 265 in the entire school.

The town has shown incredible compassion, he said, with students hanging ribbons from trees and a local furniture store offering Eli's family a new bedroom set at a deeply discounted cost.

"The community has really rallied around [Eli's family]," Plunkett said.