Doctors say Respiratory Syncytial Virus, also known as RSV has arrived in the Pioneer valley.
The highly contagious diseases makes it's way throughout New England every year when the temperatures drop.

Baystate Pediatrician Robert Kaslovsky says, "This year we've been seeing a lot of children in the hospital with RSV. Swine flu was the biggest thing in November and early December and and then from Christmas time now through the end of January we've seen a lot of RSV in the hospital."

Symptoms of RSV are similar to those of the common cold. A runny nose, cough and fever.
But it can be more dangerous.
RSV is the most common cause of bronchiolitis and pneumonia in children under the age of one.

Kaslovsky says, "Many times a child will have a little sniffle and a mild cough and that's not much of a concern but bronchiolitis from RSV tends to cause wheezing. A whistling noise in the chest and it makes it so the infants breath very rapidly and it makes them have retractions where the chest is sinking in when they are breathing. They also might refuse or not be able to suck the bottle because they are breathing so hard and that's definitely a concern."

Health officials say where parents need to be most careful is at child care facilities.
Kimberly Lee is the Vice President at Square one and says with so many children in confined spaces it's hard to prevent it.
But she urges parents to keep sick kids at home and teach them how to wash their hands often.

Lee says, "You have so many parents who rely on quality early education and care for their children. Even in this cold weather and it really limits the amount of time the children spend time away from each other. So you have a warm environment like a childcare center and lots of children in one place for lots of time. It can tend to be a breeding ground."

Doctors say while virus is serious there is no need to panic.
However if your child is showing any signs of RSV you should get them to a doctor ASAP.