Abstract
Human immunodeficiency virus (HIV) infection in children is usually vertically acquired from the mother, in utero, intrapartum, or via breastfeeding. In this case, we report the probable case of horizontal transmission of HIV between two siblings. Based on the available clinical and laboratory data, perinatal, sexual, and health care-related transmission are unlikely. Although rare, this method of transmission needs to be recognized, especially in the setting of direct contact with an individual with poorly suppressed HIV viral infection.