How did Mrs Tennyson say that her family got sick in the book Holes?

In the book "Holes" by Louis Sachar, Mrs. Tennyson explains that her family became sick due to a curse placed on them. This curse was said to have originated from a witch named Kissin' Kate Barlow, who was wronged in the past. As a result, the Tennyson family faced misfortunes, including illness, which they believed were connected to this longstanding curse.