DENVER -- A highly contagious respiratory virus that primarily affects babies and young children has reached epidemic levels in Colorado.
Respiratory syncytial virus is the most common cause of lower respiratory tract infections among young children in the United States and worldwide, according to the Centers for Disease Control and Prevention.
"Most infants are infected before 1 year of age, and virtually everyone gets an RSV infection by 2 years of age," the CDC said.
RSV Alert, which collects and reports information on RSV testing from hospitals such as Children's Hospital Colorado and University of Colorado Hospital, shows 40.5 percent of tests in Colorado were positive in the week ending Jan. 14. Just 20.8 percent of tests were positive one week earlier.
In Denver, about 30.5 percent of tests were positive in the week ending Jan. 14.
Community outbreaks of RSV infections typically occur during late fall, winter and early spring, according to the CDC.
Each year, RSV leads to an average of 2.1 million outpatient visits and 57,527 hospitalizations among children younger than 5 years old, the CDC reports.
There is no approved treatment for RSV.