Three more cases of whooping cough have been confirmed in Ravalli County.
That brings the total number of people infected to 22, including 19 children.
One of those children is an infant who has now been hospitalized.
NBC Montana is being told by the Ravalli County Health Director that the infant was not immunized against pertussis.
Judy Griffin says, "The unimmunized children or the babies under one or any child that isn't immunized or completely immunized. You can start your series and have one or two shots of DTaP and not be fully immunized and that puts you at risk if you come in contact with pertussis."