Lyme Disease
Cases
= 13In 1999, a total of 13 cases meeting the Centers for Disease Control and Prevention (CDC) confirmed case definition were reported in Indiana. Cases were reported in 3 females and 10 males. The age range was from age 7 years to 73 years. Cases had a median age of 38.7 years. Figure 1 shows the residences of confirmed cases, which may not represent the county where the infection was acquired.
Figure 1.
Since 1995, reported Lyme disease cases have varied from a low of 13 cases to a high of 23. The average number of cases has been 17.4. Figure 2 presents the number of cases by year from 1995 to 1999. During that time period, cases have been reported in 37 females and 50 males for a female to male ratio of 1:1.35. This distribution may be related to differences in occupational and recreational exposures.
Figure 2.
Lyme disease is maintained in nature in a cycle involving mice, deer, and the tick, Ixodes scapularis. Transmission to humans is through the bite of the tick. Surveys for the tick in Indiana have identified the vector most frequently in the northwestern counties of Indiana. Each year the tick’s presence is identified in additional counties and is potentially present in all counties. I. scapularis ticks were identified in 5 additional counties in 1999 bringing the total number of counties with at least one tick identified to 47. Figure 3 illustrates the number of Lyme disease cases reported by county of residence since 1990.
Figure 3.
