Introduction to Epidemiology Assignment 1

ID
The University of Western Sydney
School of Science and Health
Introduction to Epidemiology (401076)
ASSIGNMENT 1
Spring, 2019
Due date: 24/08/2019 11:55PM
This assignment is based on the learning objectives and concepts in in weeks 1 to 3
(not including measures of association). There is a total of 60 marks and this
assignment will contribute 20% towards the total assessment for this subject.
Your assignment should be typed, with adequate space left between questions.
Assignments should be submitted via vUWS (see specific instructions relating to
Assignment 1 on vUWS).
Be as brief as possible in your answers, and use the number of marks for a question as
a guide to how much to write.
No answers need to be longer than a few short sentences or short paragraphs. No need
for referencing
Late assignments will not be accepted without prior approval. Any request needs
supporting documents.
Remember to save your assignment to make sure it is the final version and
submit only this. as:
Family name First name_StudentID_Ass1_final
After due date I will not be able to remove the assignment. It is controlled by
Turnitin!! So, the only version that will be corrected is the last one you submitted
before due date

ID
Question 1(14)
(1a) “In June 2009, a study was conducted to determine the prevalence of flu in health
professionals who had patient contact and worked in three Melbourne hospitals, Of
the 165 participants, three were serologically confirmed flu cases. “
a) What was the prevalence of flu among health professionals in Melbourne? [2
Marks]
Prevelence= affected persons
population = 3
165∗100=1.81812
The prevalence of flu among the health workers for the month of June was
1.8182%.
“(1b) In December 2009, another study was conducted to determine the prevalence of
flue among health professionals with patient contact, working in three Melbourne
hospitals. Health professionals were asked whether they had experienced flu-like
symptoms during the previous winter (June-August). Of the 165 participants, 25
responded in ‘yes’ to this question.”
(b) What was the prevalence of flu according to this question? [2 marks]
Prevelence= affected persons
population = 25
165∗100=15.15 %
During the period June-August 2009, the prevalence of flu among the health
professionals was 15 for every 100 workers.
“(1c) The average duration of flu is estimated as two weeks (14 days). Can you
estimate the incidence rate of flu in the winter season for June 2009? A hint: when
computing, you need to use the decimal version of the prevalence” (4 marks)
The disease prevalence is 15.15% for the period June to August. By definition the
incidence is the number of new cases of the disease in relation to the number of
people who are at risk of being infected.
Incidence prevelence
average duration =15.15
14 =1.082, hence the disease incidence was 1.082%
per day
“(1d) In the same study of flu among health professionals in Melbourne started in
June 2009 (see a) the participants were followed up to the end of the winter season.
Within this time frame, there were 22 people serologically confirmed flu cases. What
was the incidence of flu in the 2009 winter season (June August)?” (4 marks)
Incidence is New cases
population at risk = 22
165−3∗100=13.58 %. the incidence of flu for the
period was 13.58 people for every 100 professionals.

ID
(1e) What is the difference between the incidence rates you have computed in 1c, and
1d [2 marks]
In 1c the incidence is calculated for the month of June only while in 1d the value is
obtained for the entire winter period that is June- August.
Question 2
This figure presents the occurrence of disease in 7 individuals who were followed for
7 years.
a) Calculate the incidence of the disease [4 Marks]
Since the period of observation differs e apply the incidence rate
IR¿ New cases
Total persons year of observation = 3
7 +7+2+7+3+ 2+ 5 = 3
3 3
This is 9.09 cases per 100 persons year of observation.
(b) Calculate the cumulative incidence of the disease [2 Marks]
For this study, it is not possible to obtain the cumulative incidence of the
disease since the period of observation varied for each individual under study.
(c) What is the average duration of the disease? [2 Marks]
This is the mean time that the disease affects the people
¿ 10
3 =3.333 years
Question 3: (16 points)