HLSC 4530

Principles and Application of Epidemiology

Morbidity & Mortality Rates Computation

Fall Semester – 2021

(Exam #4 – Final)

The Second Avenue School of the Tiller County School District has an enrollment of 271 pupils. During October and November, 71 of those pupils were absent with measles. What was the attack rate for measles in the Second Avenue School during October and November? (Percent)

In the Second Avenue School, 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? (Percent)

In the Second Avenue School District, the 71 pupils with measles had 93 brothers and sisters at home. Of these, 51 siblings were in what would be classified as the “lower” socioeconomic group. The rest were in the “middle” and “upper” socioeconomic groups. Of the 21 cases of measles in these 93 children, 5 were in the “middle” and “upper” socioeconomic groups.

Calculate the following:

(a) The attack rate among the “Middle & Upper” group.

(b) The attack rate among the “Lower” group.

An outbreak of gastroenteritis occurred at a liberal arts college with a student enrollment of 1164. Forty-seven (47) students had sought care at the college Health Center between 10:30 p.m. on January 17 and 8:00 p.m. on January 18. The ill students seen at the Health Center all lived in dormitories totaled 756. The dormitory of residence of the 47 known cases, as well as the population and gender of the occupants of each dormitory is shown in the table below:

Dormitory Gender Pop. of Dormitory Number of Cases

1 F 80 19

2 F 62 2

3 F 89 0

4 F 61 1

5 F 53 5

6 F 35 0

7 F 63 0

8 F 103 4

9 M 35 1

10 M 37 0

11 M 34 1

12 M 62 13

13 M 32 1

14 M 10 0

Total 756 47 _________________________________________________________________

Use the above information to answer the following:

(a) Calculate the combined attack rate of the two most affected dormitories.

(b) Calculate the attack rate for the remaining 12 dormitories.

(c) Compare the attack rates calculated in “a” and “b” above. Explain this ratio.

(d) What proportion of the cases were in the two most affected dormitories?

(e) Calculate and compare the sex-specific rates for the dormitories population.

During 1972, 29 cases of tularemia occurred in a county with a population of 7,000 persons. Calculate the incidence of tularemia per 100,000 persons in that county during that year.