<prompt> Disease rate isRisk of susceptibilityPrevalence rateTime period in a calendar yearDisease occurrence in a specified time period  <response>: Attack rate case rate or diesease rate:it is an incidence rateusually expressed in percentused only when population is exposed to risk for a limited period of time such as during an epidemicattack rate no. of new cases of a specified disease during a specified time interval total population at risk during the same interval x 100ref: Park;s 23rd edition pg 61 