Table 1. Comparisons of the Incidence Risk of La Crosse Virus Infections for At-Risk Population Groups at the County and Census Tract Levels in eastern Tennessee, 1997–2006.

	Incidence Risk per 100,000 persons
	County Level			Census Tract Level
Population Groups	n*	Median	Range	n*	Median	Range
Total population (All areas)	18	7.6	0.0–46.9	230	0.0	0.0–133.3
Total population (Only areas reporting cases)	14	8.8	0.9–46.9	55	27.7	11.9–133.3
Population 18 years and younger (All areas)	18	26.3	0.0–188.4	230	0.0	0.0–547.1
Population 18 years and younger (Only areas reporting cases)	14	35.0	3.9–188.4	52	114.6	44.3–547.1
Population 15 years and younger (All areas)	18	31.4	0.0–226.4	230	0.0	0.0–673.9
Population 15 years and younger (Only areas reporting cases)	14	41.5	4.67–226.4	51	126.7	50.9–673.9

^*Number of counties or census tracts used for each specific analysis.