<prompt> Which of the following is a characteristic of a point source epidemic?Herd immunity regulates spread of casesPerson to person transmission is seenSecondary waves of cases is always seenAll cases develop within one incubation period  <response>: .point source epidemics ,here the period of exposure is only brief,and simultaneous ,the resultant cases will develop within one incubation period of the disease.the curve has usually one peak.the epidemic curve rises and falls rapidly, with no secondary waves.and it tends to be explosive. ref:parks textbook,ed 22,pg no 62 