Table 1: Clinically Significant Arthropod-Borne Virus (Arbovirus) Encephalitides In North America

Table 1:
Clinically Significant Arthropod-Borne Virus (Arbovirus) Encephalitides In North America
Virus	Distribution	Age Affected	Mortality Rate	Amplifying Host	Ratio of Infection to Encephalitis
West Nile	Northeast US	Over 50	5-10%	Birds	150:1
St. Louis	Throughout US, but especially the Ohio and Mississippi valleys	All ages	Up to 20% in the elderly	Birds	200:1
Western Equine	Western North America	All ages	5%	Birds	1000:1
Eastern Equine	Atlantic and Gulf coasts	All ages	30-50%	Marsh birds	20:1
La Crosse	Midwest	Under 15, 90% males	1%	Chipmunks, squirrels	25:1