The number of whooping cough cases has climbed to 54, Island County health officials said Friday.

And most of those who have been diagnosed with whooping cough during the recent outbreak have been children, said Island County Medical Officer Roger Case.

All told, 52 of 54 reported cases are children with pertussis. Most of the cases have occurred among the 7 to 11-year-old bracket.

South Whidbey schools have the highest noncompliance rate for immunization against pertussis — 20.9 percent — of the three primary Island County school systems.

“We are running a check on the immunization status of those classified as confirmed, probable and suspected as to whether they were fully immunized for their age, partially immunized or never immunized and will have this information at the completion of this outbreak,” Case said late Friday.

The Coupeville School District had a non-compliant rate of 10.4 percent and Oak Harbor, 8 percent.

Most of the cases have been discovered on Central and South Whidbey. Only seven cases have involved patients north of Coupeville.

All cases of pertussis should be reported to the Island County Health Department immediately at 360-679-7350.