Question 19M.2.HL.TZ1.f
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.f |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | f | Adapted from | N/A |
Ebola virus disease (EVD) is the disease in humans and other primates that is caused by the Ebola virus. Fruit bats are the reservoir for the virus and are able to spread the disease without being affected. Humans can become infected by contact with fruit bats or with people infected by the virus, their body fluids or equipment used to treat them.
The stacked bar graph shows the epidemiological data for the EVD cases in Conakry, the capital city of Guinea, surrounding suburbs and rural areas in Guinea from the beginning of January 2014 to the end of March 2015.
[Source: Adriana Rico, et al. “Epidemiology of Epidemic Ebola Virus Disease in Conakry and Surrounding Prefectures,
Guinea, 2014–2015.” Emerging Infectious Diseases 22.2 (2016): 178–183. PMC. Web. 23 Mar. 2017.
https://wwwnc.cdc.gov/eid/article/22/2/15-1304_article]
The table summarizes epidemiological data from Guinea during the Ebola outbreak in 2014. The data are based on figures supplied by Ebola treatment centres. The last column refers to people who died in places other than Ebola treatment centres.
[Source: Adriana Rico, et al. “Epidemiology of Epidemic Ebola Virus Disease in Conakry and Surrounding Prefectures,
Guinea, 2014–2015.” Emerging Infectious Diseases 22.2 (2016): 178–183. PMC. Web. 23 Mar. 2017.
https://wwwnc.cdc.gov/eid/article/22/2/15-1304_article]
An antiviral drug, T-705, was tested in order to establish whether it has potential to treat EVD. The graph shows the data from an in vitro trial of T-705 on cells that had been infected with Ebola virus five days previously. Virus concentration and live cells are shown as a percentage of the control.
[Source: Oestereich, Lisa & Rieger, Toni & Neumann, Melanie & Bernreuther, Christian & Lehmann, Maria & Krasemann,
Susanne & Wurr, Stephanie & Emmerich, Petra & de Lamballerie, Xavier & Ölschläger, Stephan & Günther, Stephan. (2014).
Evaluation of Antiviral Efficacy of Ribavirin, Arbidol, and T-705 (Favipiravir) in a Mouse Model for Crimean-Congo
Hemorrhagic Fever. PLoS neglected tropical diseases. 8. e2804. 10.1371/journal.pntd.0002804.]
Based on these data, outline the evidence that T-705 has potential to be used as a treatment for EVD.
[2]
a. cells not killed/few cells killed «even at high concentrations» ✔
b. «T-705» effective/viruses reduced/viruses killed at 100 μM
OR
«T-705» very effective/viruses much reduced/nearly all viruses killed at 1000 μM ✔
c. virus concentration decreases as T-705 concentration increases ✔
d. drug has «high» potential for treatment «at high enough concentration» ✔
This was a timely question with Ebola epidemics again causing great problems in parts of Africa. Students were expected to have had some practice at analysing data relating to an epidemic because of this Skill in the programme: Analysis of epidemiological data related to vaccination programmes. It was assumed that candidates would understand terms such as ‘case’, ‘fatal case’, ‘infect’ and ‘treat’.
This was generally very well answered, with candidates correctly concluding that the drug had potential as a treatment because at a high enough dose it reduced the number of viruses without harming a significant number of cells.
