Trends in Legionnellosis Case Counts and Rates by Age and Sex, Ontario 1978 to 2006. A marked increase in case counts and disease rates is seen with increasing age. Diminished case counts in the oldest individuals (black bars) reflect small size of population at risk; rates increase continuously (dashed black line). Case counts in males (gray bars) are higher than those in females (white bars) in all but the oldest age groups. However, as fewer males survive to extreme old age, rates of disease per 100,000 population are higher in males (gray line) than in females (solid black line) in all age groups.