A whooping cough outbreak in Nevada County that initially was reported Feb. 8 has grown from just two reported cases to a dozen. On Friday, the county announced the Public Health Department has notified all parents, guardians and school staff of a pertussis (commonly known as whooping cough) outbreak that has involved 11 school-age children and one preschool child. Two cases of the disease were reported at Yuba River Charter Feb. 8, with another case reported Feb. 22. During that time, school administrators said any student exhibiting symptoms would be sent home until cleared by a doctor. The schools with …