Practise pathogen types, transmission and prevention through cholera, malaria, tuberculosis and HIV contexts, then explain antibiotic action and resistance from evidence.
Tuberculosis (TB), influenza and polio are examples of infectious diseases.
Explain what is meant by an infectious disease.
caused by pathogens ;
is transmissible I AW ;
Name a species of organism that causes TB.
Mycobacterium tuberculosis / Mycobacterium bovis ;
Polio is a serious viral disease affecting young children. In 1996, polio caused paralysis in more than 75000 children across Africa. A long-term vaccination programme allowed the World Health Organization (WHO) to declare that Africa was largely free of polio in 2020.
Antibiotics, such as penicillin, do not help to prevent the spread of viral diseases, such as polio.
Explain why penicillin is not effective against viruses.
any one from:
penicillin only acts on, bacteria / prokaryotes ;
virus does not have, cell walls / murein / peptidoglycan ;
virus does not have, transpeptidases / the enzyme that is, inhibited / acted on, by penicillin ;
virus does not grow / penicillin (only) acts on growing cells / AW ;
A when cell wall is, growing (larger) for growing cells
virus does not have cellular structure / virus is acellular ;
In March 2019, a tropical cyclone in the south-west Indian Ocean caused widespread flooding in a number of countries.
The flooding and the damage caused by the cyclone meant that many people were at serious risk of cholera.
After the natural disaster occurred, many different areas reported outbreaks of cholera. Within a short time the disease had spread widely and large numbers of people were affected.
Cholera is caused by a bacterial pathogen.
Name the bacterial pathogen that causes cholera.
Vibrio cholerae ;
Suggest and explain why the people affected by the cyclone were at serious risk of cholera.
any three from:
1 cholera already, endemic / present, in area ;
2 contaminated water / water contains pathogen ;
R polluted water
3 pathogen transmitted by, faecal-oral route / AW ;
4 ref. to changed living conditions ;
e.g. no piped, treated, drinking water / disruption to water treatment plants no safe disposal of sewage / disruption to sewage treatment plants
5 ref. to inability to practise good hygiene ;
e.g. washing (utensils) in contaminated water not able to wash hands after defaecation latrines not covered
6 AVP ;
e.g. ref. to flies transferring pathogen from, uncovered latrines / (contaminated) faeces
In addition to the standard treatment for cholera, antibiotics are recommended for people who are moderately ill or seriously ill with the disease.
Penicillin, which used to be prescribed for the treatment of cholera, has a different mechanism of action to doxycycline.
State which part of the bacterial cell is affected by the action of penicillin.
cell wall ;
Mozambique was one of the countries badly affected by the cyclone.
As part of the effort to prevent a greater number of cases of cholera from occurring, two different approaches were taken.
- Approximately 900000 doses of the oral cholera vaccine were sent to Mozambique and a large-scale vaccination programme was organised.
- Medical centres were set up in Mozambique to treat people with cholera.
Suggest and explain how the two different approaches helped to prevent a greater number of cases of cholera from occurring.
any four from:
vaccination programme to max 3:
1 vaccines stimulate (active) immunity to cholera / AW ;
2 idea that if infected with, pathogen / V. cholerae, people do not become ill with cholera or the immune system destroys pathogen before it can, cause harm / spread ;
3 ref. to herd immunity ;
A described e.g. enough people effectively immunised to prevent spread idea that unvaccinated people surrounded by immunised people
4 AVP ;
e.g. idea that reduces reservoir of pathogen in population
treatment to max 3:
5 (oral / intravenous) rehydration therapy, decreases recovery time / cures more quickly ;
6 (more likely that) contaminated faeces disposed of safely / decreased risk of spread via contaminated faeces
7 more able to practise good hygiene ;
8 time spent in medical centre acts as quarantine / infected people not in general population ;
9 (so) decreases, density / proportion, of infected people to reduce risk of spread ;
10 AVP ;
e.g. medical centres able to monitor antibiotic use and provide most effective medication medical centres, accessible to many parts of the country / widespread idea that medical centres mean people treated sooner decreasing time when people are infectious injecting antibodies