Although Kawasaki syndrome (KS) has been suspected to be caused by an infectious agent,1-4 no etiologic agent has been identified to date and epidemiologic data have demonstrated no evidence of person-to-person transmission or common exposures of patients with KS.3-5 We describe two cousins in close contact in whom KS developed within a two-week interval in April 1981. Both patients' illnesses were associated with seroconversion to parainfluenza virus type 3.
Report of Cases.—Case 1.—Five days after exposure to a sibling with an upper respiratory tract infection, a 20-month-old black boy had rhinitis and fever (temperature, 38.5 °C). On the following day, his temperature was 40 °C and a macular rash covered his chest and back; bilateral conjunctival injection, palmar erythema, and a 2 × 3-cm cervical node were noted on examination. By the fourth day of illness, swelling of his ankles, hands, and feet developed and his lips became