The medical director at the Louisville Department of Public Health and Wellness says there hasn't been a dramatic jump in the number of whooping cough cases in Jefferson County this year.In nearby Bullitt County, officials at Freedom Elementary School are battling the spread of the illness, which has been confirmed in nine students over the past month.The Louisville health department's Dr. Matt Zahn says the local incidence has been about average."Every year we will have cases of whooping cough, or pertussis here in Louisville. This year, I can't say we're having a huge number of cases, but we definitely have cases," Zahn said.Whooping cough is a highly contagious illness of the respiratory system. It can be treated with antibiotics.Zahn says there's a common whooping cough vaccine for small children, but a booster might be necessary for older children and adults.