Science Olympiad » Disease Detectives Event » Sample Problems and Answer Keys
Problem: Ebola Hemorrhagic Fever, Hepatitis B, and Multiple Sclerosis

Read the following articles on the outbreak of Ebola Hemorrhagic Fever. Refer to the article for the following questions.

	See Also... Answer Key

Outbreak of Ebola Hemorrhagic Fever  
— Uganda, August 2000-January 2001. Morbidity and Mortality Weekly Report. February 09, 2001. 50(05):73-77.

Ebola Outbreak in Uganda
— CDC Media Relations: Media Advisory

Ebola: Case Table
— CDC: SPB: Disease Information: Fact Sheets

Questions

1. What are the two strains of Ebola virus? (2 points each)

 

2. What strain caused this outbreak? (1 point)

 

3. What is the equation used to calculate the case-fatality rate? (3 points)

 

4. What was the case-fatality rate in this outbreak? (2 points)

 

5. Why did the investigators follow contacts of case-patients for 21 days? (4 points)

 

6. Approximately how long did it take for this outbreak to be recognized? (2 points)

 

7. Give one possible explanation why women were affected more than men. (4 points)

 

8. How did the virus spread from Gulu to Mbarra and Masindi? (1 pt)

 

Read the following abstract on the hepatitis B vaccine and multiple sclerosis. Refer to these articles for the following questions.

Abstract

Hepatitis B vaccination and the risk of multiple sclerosis. Ascherio A, Zhang SM, Hernan MA, Olek MJ, Coplan PM, Brodovicz K, Walker AM. New England Journal of Medicine. February 1, 2001. 344:(5)327-332.

Background: Reports of multiple sclerosis developing after hepatitis B vaccination have led to the concern that this vaccine might be a cause of multiple sclerosis in previously healthy subjects.

Methods: We conducted a nested case-control study in two large cohorts of nurses in the United States, those in the Nurses' Health Study (which has followed 121,700 women since 1976) and those in the Nurses' Health Study II (which has followed 116,671 women since 1989). For each woman with multiple sclerosis, we selected as controls five healthy women and one woman with breast cancer. Information about hepatitis B vaccination was obtained by means of a mailed questionnaire and was confirmed by means of vaccination certificates. The analyses included 192 women with multiple sclerosis and 645 matched controls (534 healthy controls and 111 with breast cancer) and were conducted with the use of conditional logistic regression.

Results: The multivariate relative risk of multiple sclerosis associated with exposure to the hepatitis B vaccine at any time before the onset of the disease was 0.9 (95 percent confidence interval, 0.5 to 1.6). The relative risk associated with hepatitis B vaccination within two years before the onset of the disease was 0.7 (95 percent confidence interval, 0.3 to 1.8). The results were similar in analyses restricted to women with multiple sclerosis that began after the introduction of the recombinant hepatitis B vaccine. There was also no association between the number of doses of vaccine received and the risk of multiple sclerosis.

Conclusions: These results indicate no association between hepatitis B vaccination and the development of multiple sclerosis.

9. According to the study by Ascherio et al, the relationship with the hepatitis B vaccine and MS is (1 point)
1. Hep B vaccine associated with relapse of MS.
2. No association between Hep B vaccine and MS.
3. Hep B vaccine not associated with relapse of MS.
4. Hep B vaccine associated with onset of MS.

 

10. The study method used by Ascherio et al. was (2 points)

 

11. Describe in three to four sentences how this study may have been designed. (5 points)

 

 

12. Describe one advantage of conducting this type of study. (3 points)

 

13. The study method used by Confavreux et al. was (1 pt)

 

14. In this type of study, a person serves as both a case and a control. List one possible advantage of this type of study. (3 points)

     

15. According to the study by Confavreux et al., the relationship with the hepatitis B vaccine and MS is (1 point)
1. Vaccines are associated with relapse of MS.
2. No association between vaccines and MS.
3. Vaccines are not associated with relapse of MS.
4. Vaccines are associated with onset of MS.

 

16. What was the percentage of parents who believed that their children’s immune system could be weakened by too many immunizations? (1 point)

     

17. The risk measurement for a case-control study is (3 points)

 

18. What is the equation to calculate this measurement. (3 points)

 

19. The risk measurement for a cohort study is (3 points)

 

20. What is the equation to calculate this measurement. (3 points)

 

Answer Key

Tiebreaker #1

Match the person in Column 2 to their accomplishment in Column 1.

Tie breaker #2

Define the following three terms.

1. Endemic
2. Pandemic
3. Epidemic

Answer Key

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