Epiville

SARS Outbreak Study 2

Study Design

Now you are ready to move forward with designing a study. One of the first and most important steps in any study is developing specific aims and hypotheses.

  • Who is at risk of becoming ill?
  • What is the disease?
  • Where is the source of the epidemic?
  • What type of epidemic is this?
  • What is the route of transmission?
  • What measures to control the outbreak should be implemented?

1. Based on the facts as presented, select the answer below that represents the best hypothesis for the agent and transmission of SARS as well as the optimal control policy for the Amory Apartment Complex.

  1. The possible agent of infection is coronavirus. The most likely spread of SARS is person-to-person.
  2. The possible agent of infection is coronavirus. The most likely spread of SARS is person-to-person. The best approach for control of future SARS outbreaks is isolation of cases and quarantine of exposed.
  3. The most likely mode of transmission of SARS is vector-borne, a mosquito. The best approach for control of the future SARS outbreaks is to stop traveling by airplane.
  4. The possible agent of infection is a West Nile Virus. The most likely mode of spread of SARS is through sexual contact.
Answer (a) — incorrect: While it is correct that the causing agent of the SARS epidemic is coronavirus and the most likely mode of spread of infection is person-to-person, this answer does not provide information on the control measures which will stop the outbreak.
Answer (b) — correct: Based on what we know about SARS so far, the best formulated hypothesis is one that includes coronavirus as the most likely agent of infection, spread of SARS via person-to-person and isolation of cases and quarantine of exposed as measures of control of the spread of epidemic.
Answer (c) — incorrect: From the previous SARS epidemic we have no data regarding its mode of transmission via mosquitoes. While it is certainly true that airplane travel has played a role in the spread of the SARS epidemic around the globe, it is unlikely that banning air travel to affected areas will completely stop the epidemic as the epidemic can spread by many other ways, e.g. local travel by buses and on foot.
Answer (d) — incorrect: Symptoms which are characteristic of West Nile virus infection differ from those of SARS infection, and therefore, the case definition of SARS cannot be met. In addition, the CDC has established that SARS is caused by a virus from the corona family, not by a West Nile virus. It has also been established that the most likely way to spread SARS is person-to-person