Respiratory syncytial virus (RSV) has been raging along the Wasatch Front. But there are signs the common respiratory illness, which can be dangerous for very young children, may have peaked for the season.

RSV cases confirmed by the Intermountain Healthcare Central Lab reached 230 a week two weeks ago — the highest number so far this season. The week ending Feb. 9 saw 213 confirmed cases, said Bonnie Midget, spokeswoman for Primary Children's Medical Center.

One week does not a trend make, but health experts anticipate the numbers will continue to decline.

RSV is the most common cause of bronchiolitis and pneumonia among infants and children under age 1. It typically begins with fever, runny nose, cough and sometimes wheezing. The illness, while not restricted to any age group, hits the youngest the hardest. "It's generally the little, little guys that become the sickest," Midget said. Children born with medical problems also are more vulnerable to becoming very ill with the virus.

It's spread through respiratory secretions and can live for a few hours on surfaces, but it's readily inactivated with soap and water and disinfectants, according to the National Center for Infectious Diseases. The virus seems to be more active during winter months. For children with mild disease, treatment may be solely to deal with symptoms and the vast majority of cases can be managed a home. Very ill children may need to be hospitalized and, in severe cases, a child may require mechanical help to breathe.

Good hygiene and hand washing is important to avoid spreading RSV. "For newborns, this is not a good time to take them to public places," said Midget. "Be observant. If a child is sick, struggling to breathe or if you're just concerned, see your health-care provider."

The RSV year runs from July to June and it typically peaks sometime between January and March.

There are RSV cases statewide, but most of the confirmed cases are in the Salt Lake area this year, Midget said. And it's an undercount, since not all children who have the illness are lab tested for it.

Last year, the lab confirmed about 150 cases a week at its peak. But this year's higher numbers are no surprise, Midget said. For unknown reasons, the virus seems to operate on a two-year cycle. A milder year is typically followed by a more virus-active year, like this year. Experts predict next year will again be more mild. The pattern has been pretty consistent for more than 15 years.