I am a little surprised that school officials have not contacted your sister sooner. You did not state how old your niece is however. Your sister will have problems with school authorities if she does not re-register or re-enroll the child in a school program as soon as possible. While the child had "whooping cough" the child should have been receiving home school services for children with serious medical problems. My deepest concern is for the child who has lost a good deal of the school year for medical and emotional reasons. Steps should be taken to catch her up on her school work or she will either have to attend a summer program or repeat this school year. I would be concerned that your sister is not acting her child's best interests.