Exposure to infant siblings during early life and risk of multiple sclerosis

Abstract

CONTEXT: The "hygiene hypothesis" has implicated sibship as a marker of infection load during early life and suggests that exposure or reexposure to infections can influence the developing immune system. Viral infection has also been implicated in the pathogenesis of multiple sclerosis (MS). OBJECTIVES: To evaluate whether exposure to infant siblings in early life is associated with the risk of MS, and to explore the possible mechanism for any apparent protective effect, including altered Epstein-Barr virus (EBV) infection patterns. DESIGN, SETTING, AND PATIENTS: Population-based case-control study in Tasmania, Australia, from 1999 to 2001 based on 136 cases of magnetic resonance imaging-con..