id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-023747-mvq6353a	Ascherio, Alberto	Epidemiology of Multiple Sclerosis: Environmental Factors	2009-12-25		.txt	text/plain	8842	461	49	The epidemiologic evidence points to three environ­mental risk factors—infection with the Epstein-Barr virus (EBV), low levels of vitamin D, and cigarette smoking—whose association with multiple sclerosis (MS) seems to satisfy in varying degrees most of the criteria that support causality, including temporality, strength, consis­tency, biologic gradient, and plausibility. As discussed in this chapter, epidemiologic evidence points to three environmental risk factors-infection with the Epstein-Barr virus (EBV), low levels of vitamin D, and cigarette smoking-whose association with multiple sclerosis (MS) seems to satisfy in varying degrees most of the criteria that support causality, including temporality (i.e., the cause must precede the effect), strength, consistency, biologic gradient, and plausibility. 28 Studies within the United States have also supported a decreased risk of MS among migrants from northern (>41° to 42° N), Australia and New Zealand Europe Figure 4-1 Worldwide prevalence estimates of multiple sclerosis.	./cache/cord-023747-mvq6353a.txt	./txt/cord-023747-mvq6353a.txt