A respiratory virus is on the rise, and the most vulnerable to the virus are children under two.

Summer Donovan, a pediatrician with Little Spurs Pediatric Urgent Care, said she's seen more Respiratory Syncytial Virus, or RSV, cases.

The youngest child affected was only six weeks old.

"Older kids handle it well," Donovan said, "but younger kids, they can get very sick and end up in the hospital."

The virus causes infection of the lungs and breathing passages. On average nationwide, RSV leads to 2.1 million doctor visits among children under five. About 57-thousand of those are hospitalized.

Parents should take their children to the doctor when they see certain symptoms.

"When they breathe, some difficulties are sucking in at the ribs or breathing really fast," Donovan said.

Donovan said there are ways to prevent the virus. The most simple method of prevention is washing hands.