The etiology of the disease is unknown and a variety of infectious triggers have been suggested including rubella, echovirus 7, mumps, cytomegalovirus, Epstein-Barr virus, adenovirus, parainfluenza, parvovirus, Coxsackie, influenza, herpes, and hepatitis B and C [8] . Possible bacterial etiology including Yersinia enterocolitica and mycoplasma pneumonia has also been raised [9] . Genetic factors such as HLA-B17, B18, B35 and DR-2 have been suggested as a predisposition for SD [10] .