Question

Case study 2: Five patients in the town of Castle Rock (Population 1,026) came into the hospital between late March and late August, complaining of muscle twitching in their arms, anxiety and lethargy. Following admission to the hospital on June 25", the first patient (Patient X) became comatose and subsequently died. Before Patient 1 died he said that he started to feel bad after his hiking trip to Arizona, where he also explored some bat caves. The other 4 patients were interviewed: Patient 2: "I don't know Patient 1, but he is a customer at a bank I work at." Patient 3: "I own the laundry mat in town. Patient 1 brought in his fancy leather hiking boots and Gortex pants for us to clean. The boots were covered in dust!" Patient 4: "I clean Patient l's house once a week. That guy lives like a pig!" Patient 5: "Never met Patient 1. I work at the local café as a bus boy." 1. Would this be considered an epidemic? Explain using supporting data. 2. What is the mode of transmission for this disease? Is there a vector involved? Why/Why not? 3. Is the data showing number of patients infected in the population an example of incidence or prevalence of the disease? Explain. 4. What are the morbidity and mortality rate for this disease? 5. These cases were reported to the CDC. Why is it important to obtain detailed information about cases and report them to government agencies?

Answer 1

Ques: Would this be considered an epidemic?Explain using supporting data.

Ans: No, this case cannot be considered to be epidemic. As we know, an epidemic is the rapid spread of disease to a large number of people in a given population within a short period of time. In other words, an epidemic disease is one “affecting many persons at the same time, and spreading from person to person in a locality where the disease is not permanently prevalent.”In this case, Over a period of 6 months,ie;from late march to late august, just 5 such medical cases was reported.

Ques: What is the mode of transmission of this disease?Is there a vector involved?Why/Why Not?

Ans: The mode of transmission of this disease could be either through Air/droplet or through Surface/direct contact. . The patient 1 was in contact with other 4 patient's in some or the other way which invloved both Face to Face contact and material contact's with each other, like; handing over cash/drafts at bank, where Patient 2 worked, getting the laundry done by Patient 3 and room cleaned by Patient 4 like wise.

To understand whether a vector is involved in this case, let us first go through what is a Vector borne disease. Vector disease transmission occurs when one living organism such as a flea, tick or mosquito transmits infectious disease between animals or between animals and humans.

In this case we can clearly see , the patient's eventhough were related to each other in some or other way, they were not living in the close viscinity of the patient 1. If it was a case of vector borne disease, there would have been more such patient's and that too those who were living close and in regular contact with patient 1.

Ques: Is the data showing number of patients infected in the populaion an example of incidence or prevalence of the disease. Explain?

Ans: Incidence of disease is a measure of the probability of occurrence of a given medical condition in a population within a specified period of time. In other words, it is the number of new cases during some time period.

Whereas,

Prevalence is the number of cases both newly diagnosed and previously diagnosed in current survivors within a given population in a defined time period. It reflects the penetration of a particular disease or event within a population and can be used to evaluate the impact that treatments are having on a particular disease.

This is clearly an example of Prevalence of Disease.

Ques: What are the morbidity and mortality rate for this disease?

Ans:  Morbidity rate is the percentage of people who have complications from a medical condition or after a procedure or treatment.Morbidity rate can be calculated by taking the number of people in a given population, and identifying what percentage of those people have an incidence of illness.

Here the morbidity rate cannot be calculated as we don't have exact number of people in total population.

Mortality rate is the total number of deaths from a particular cause in 1year divided by the number of people alive within the population at midyear. Here , if we take total 5 cases as the population under that specific disease then the mortality rate will be :

Number of patient died/Total Number of Patient X 100 = 1/5 X 100 = 20

Ques: These cases were reported to CDC. Why is it important to obtain detailed information about cases and report them to the goverment agencies?

Ans: It is important to report them to government agencies for protecting the public health by making way for finding cure for the disease and arrest future spread of diseases.
Furthermore, state and local Health Departments are responsible for disease surveillance. The primary objectives of disease surveillance are to determine the extent of disease within the community, to evaluate transmission risk, and to intervene rapidly when appropriate. For surveillance to be effective, the reporting of communicable diseases must be timely.