lyme disease

The prevalence of arthritis in the United States is 1 in 100,000 children.  However, 1 in 10 children in Lyme CT, developed arthritis between June and September in 1973.  Allen Steere, a rheumatologist at Yale University investigated the cases in Lyme and found that 25% of the patients remembered having a skin rash during their arthritic episode and that the disease was treated with penicillin.  Steere concluded that this was a new infectious disease and did not have an environmental, genetic, or immunologic cause. (20 Points)
a. What was the factor that caused Steere to reach his conclusion>
b. What was the disease?
c. Why was the disease more prevalent between June and September?
d. Get out a map and look at the location of Plum Island and look into some research on what might have happened?  What is the significance of Plum Island?