Sample Case Study on Prevention and Control of Diseases

Prevention and Control of Diseases – A Case Study Assignment

Question 1

Poliomyelitis, also known as Polio, is a viral caused and transmitted disease that attacks a person’s nervous system.  It is highly contagious mostly affecting children aged five years and below. It is caused by a virus known as poliovirus. If not prevented, poliomyelitis results into a permanent paralysis.

Question 2

An incubation period is a time between a disease transmission and the beginning of its symptoms. The incubation period of poliomyelitis ranges from four to 35 days, and at this point, the disease is contagious. The incubation period helps investigators to ascertain the agent triggering an illness.

Question 3

Polio is faecal-oral transmitted whereby a stool of an already infected person gets into the mouth of another individual through contaminated food or water. Also, when an infected person’s saliva gets in contact with another person’s saliva, they contract the disease.

Question 4

Public health officials should focus on water and foods the children consumed approximately four days (the onset of the incubation period) before they became sick so as to investigate the source of poliovirus. The public officials should emphasize on unfrozen and uncooked foods because freezing and cooking make the parasite inactive. Given that all the children showed the polio symptoms almost the same time, it is doubtful that one of the children was the cause of the infection for others.  The poliovirus symptoms among the children were first seen on May 14-19. Considering that the average incubation period of the virus is seven to 14 days, the exposure time for the children was from May 5-7. If the children never shared other common exposures such as meals or drinks, it is possible that they were infected with poliomyelitis in school.

Question 5

In some cases of an outbreak, investigations are supported by some environmental, laboratory or epidemiologic information present whereby all the necessary examination is done on the established facts. However, in most investigations, the prevailing circumstances may not be that established, and this requires an analytic study, whereby the comparison between the involved groups is carried out. In an analytic study, the investigators are allowed to enumerate the relationship between a suspected disease and its exposure, explore the role of chance and to test the hypotheses about casual relationships.

The commonly used studies are the case-control study and the cohort study. In the case-control study, cases are enrolled by whether they have the disease in question. Some factors, such as previous exposure to the disease, are compared between cases and controls to know if the disease and the exposure have any relationship. In a cohort study, cases are enrolled by exposure or lack of exposure to a factor of interest. The disease occurrence is then determined and compared to people exposed to the factor in question and those without exposure to know if there is any relationship between the disease and the exposure.

A cohort study is the best suited for this investigation because it applies in a situation where the disease affects a well-defined population, when the disease is common and when the exposure is rare. A case-control study, on the other hand, applies to an unknown group at risk, in a rare disease, and when there is a common exposure.

Question 6

Analysis of cases of any given diseases alone is not sufficient in determining the relationship between the disease and exposure. Exposures common or prevalent among given cases may just be common in the group and not related to the diseases. This means a comparison group is required to determine the extent of the exposure in the group.

Question 7: Interpretation of the results

Based on the results of the cohort study, it can be concluded that the rate of attack of poliomyelitis was very high (90%) among those who ate food from the local butcher.  At the same time, the attack rate was low (9) among students who did not eat from the local butcher (Aguolu, 2015).  This means that the relative risk was very high in the cohort because people who ate from the local butcher were ten times likely to get infected with poliomyelitis than those who did not eat from the local butcher.

Question 8

When reviewing epidemiologic study results, one should examine other conceivable explanations for given findings. Some items should be considered when interpreting the results. They include selection bias, confounding or explanatory factors, information bias, and investigator error.

Question 9

Additional studies that might refute or confirm the hypothesis that Poliomyelitis outbreak resulted from meat from the local butcher include:

  • Collecting samples of meat from the local butcher and testing them in the laboratory to ascertain if they are infected with poliomyelitis
  • Conducting a parallel study on other poliomyelitis cases within the same area as well as other area and investigating their causes.
  • Tracing the meat eaten by the victim to the original seller to ascertain if it was imported and whether it was infected or not and its effects on other consumers.

Question 10

Interview Questions for a Newspaper Article

  1. a) The Parent of the infected child
  2. When did your child start exhibiting symptoms of poliomyelitis?
  3. Which type of meat did you buy and where did you buy it?
  • Can you explain your child’s whereabouts before the outbreak including eating patterns and hygiene?
  1. b) The owner of the elementary school where the outbreak occurred
  2. When did the outbreak take place?
  3. How many children have been affected?
  • What steps have you taken to safeguard children who are not affected as well to remedy those affected?
  1. c) The attorney for the Butchers Association
  2. Where do your clients obtain the meat they sale?
  3. What hygienic standards do they observe when dealing with meat?
  • Are you aware that poliomyelitis outbreak is linked to meat imported by your clients?
  1. d) CDC Experts on Poliomyelitis
  2. What are the link between poliomyelitis and meat?
  3. Have you analysed meat samples from Trans-Carpathian region?
  • What steps should parents take when they suspect cases of poliomyelitis outbreak among their children?




Aguolu, G. (2015, September 22). Prevention and Control of Diseases. Retrieved Janaury 30, 2017, from BBC News: