Epidemiology – HPRO 7712 Fall, 2018 Final Examination Part B Name: Date: 12/5/2018 Please perform calculations and respond to the following questions. 1. One hundred and eight (108) cases of staphylococcal food poisoning were reported in a rural community in August 1989. Incubation period was 2-6 hours. First case occurred at 8:00 p.m., August 6 and last case occurred at 4:00 a.m., August 7, 1989. Peak of cases was at 10:00 p.m. Based on the information provided above, what was the most likely period of exposure to the source of epidemic among the cases? (5 points) 1. An outbreak of 110 cases of gastroenteritis occurred at a liberal arts college with a student enrollment of 1164. Having identified the meal to which the students most probably were exposed, and knowing each student’s time of onset of symptoms, it was possible to calculate incubation periods for 101 students. From a summary line listing of incubation periods (in one-hour intervals) and number of cases, calculate the median incubation period of cases in hours. (6 points) Incubation Period (in hours)Number of Cases 1. (fi) _____________________________________ 822 911 1018 11 8 1. 42 ______________________________________________________ Total 101 1. The Second Avenue School of the Tiller County School District has an enrollment of 271 pupils. During October and November, 71 of these pupils were absent with measles. 2. What was the attack rate for measles in the Second Avenue School during October and November? (4 points) 2. The 71 pupils with measles had 93 brothers and sisters at home. Of the 93, 21 developed measles. What was the secondary attack rate in the brothers and sisters? (4 points) 1. During the evening of July 4, a total of 17 persons were given emergency treatment at a suburban community hospital for a condition diagnosed as staphylococcal intoxication. Interviews with these persons led to the identification of an additional 39 people who were ill with signs and symptoms compatible with staphylococcal intoxication but who did not seek medical attention. Further investigation revealed that all the ill persons and 42 others who did not become ill had attended an all-day picnic on July 4. What is the attack rate of staphylococcal intoxication among the group that attended the picnic? (5 points) 1. Using the information in situation #4 above, 14 of the cases and 37 of the well persons were females (a). Calculate the sex-specific attack rates. (10 points) (b). Calculate the ratio of the rate in males to the rate of females. Interpret the ratio. (5 points) 6.Again, using the information in situation #4 above, upon further investigation, 53 of the ill persons and 3 of the well persons could definitely remember they had eaten potato salad that had been prepared at the home of one of the families attendi.