Question 19M.2.HL.TZ1.1h
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.1h |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Suggest | Question number | h | 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.]
In 2015, an experimental vaccine was trialled in Guinea in an area where new Ebola cases continue to develop. Among the nearly 6000 people who accepted the vaccine, no cases were recorded after vaccination. In comparison, there were 23 cases among those who did not accept the vaccine.
Suggest possible reasons for the difficulty of preventing or controlling a viral epidemic such as the 2014 EVD epidemic in a remote rural region.
[2]
a. poor transport infrastructure/poor communication/bad roads/difficult access/no maps/support slow arriving/scattered population ✔
b. poor education/understanding of disease amongst health workers/local population
OR
continued contact with infected people / other example of unsafe actions ✔
c. more sources of infection such as bats/difficult to find sources of infection ✔
d. lack of/limited access to medical care/doctors/health care workers ✔
e. lack of/no access to/unaffordability of treatment centers/medicalsupplies/equipment/antivirals/drugs/vaccine/treatments ✔
f. refusal/reluctance in local population to be vaccinated
OR
difficult to find/reach everyone to vaccinate them/repeat the vaccination ✔
g. migration of people spreads the infection ✔
h.poor sanitation/lack of clean water ✔
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 a third question where a very wide range of answers were accepted. Even so, not all candidates scored both marks. The commonest weakness was vague answers such as “shortage of resources”. The best answers gave common-sense reasons for special difficulties in controlling an epidemic in the population of a remote rural region.
