HAMILTON, Mont. -

The state reports four new pertussis cases in Ravalli County. That brings the Bitterroot's confirmed whooping cough number to 19.

Ravalli County Public Health is still investigating these cases. We don't know hometowns yet.

But public health officer Dr. Carol Calderwood said it appears the new patients are of mixed ages. Until now, almost all the cases in the outbreak have been children.