Lyme Disease
Cases
= 22In 1998, a total of 22 cases of Lyme disease, which met the CDC confirmed case definition, were reported in Indiana. Cases were evenly divided between males and females. The age range was from 1 year to 66 years (Median age: 36.5 years). Figure 1 shows the county of residence of confirmed cases, which may not represent the county where the infection was acquired. Note that county of residence was unknown for 2 cases.
Figure 1.
Since 1991, reported Lyme disease cases have varied from a low of 16 cases to a high of 32. The average number of cases has been 19.9/year. Figure 2 presents the number of cases by year from 1991 to 1998.
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. Figure 3 illustrates the counties and the number of Ixodes scapularis ticks identified in those counties since 1987. Figure 4 illustrates the number of Lyme disease cases reported by county of residence since 1991.
Figure 2.
Figure 3.
Figure 4.
