Self-Assessment Questions (SAQs) for Study Session 5
Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.
SAQ 5.1 (tests Learning Outcome 5.1)
A person from a malaria-free place visiting a high malaria risk area shows signs and symptoms of malaria after 8 days of his stay in the area. Which of the following types of malaria parasites is the person most likely to be infected with: P. falciparum, P. vivax, P. ovale or P. malariae? Explain how you reached your answer.
P. falciparum is the most likely cause of the infection, because the symptoms began after 8 days. The period between infection with the parasites that cause the disease and the beginning of malaria symptoms (incubation period) for P. falciparum is 7–14 days. It is longer for the other species of Plasmodium.
SAQ 5.2 (tests Learning Outcome 5.2)
You have learned that the burden of malaria in Africa is higher than other parts of the world, and also that the malaria incidence varies in different regions of Africa. Where in Africa is the incidence of malaria highest? Where is malaria incidence low?
- Malaria incidence is high in countries around the tropics or closer to the equator.
- It is low in northern and southern African countries.
SAQ 5.3 (tests Learning Outcome 5.2)
The distribution of malaria in Ethiopia is not uniform. What are the possible explanations for the difference in malaria incidence in different areas of Ethiopia?
- Malaria incidence is high in the western lowlands of Ethiopia where the temperature and humidity is high and favourable for mosquito and parasite development.
- There is no malaria in the highlands because of low temperature.
- There is less malaria in the eastern lowlands because rainfall and humidity are low.
SAQ 5.4 (tests Learning Outcome 5.3)
Carefully study the life cycle of the parasite in the human body and the mosquito (see Figure 5.5). List the body parts of the mosquito and the body parts of humans that are directly associated with parasite development and reproduction.
The body parts directly associated with the development and reproduction of the malaria parasites are:
- Mosquito: gut and salivary glands.
- Human: liver and red blood cells.
SAQ 5.5 (tests Learning Outcome 5.4)
The following are statements about the life cycle of the malaria vector mosquito. Which of these statements is false? In each case, explain what is incorrect.
A The malaria vector mosquito lays its eggs on grass.
B The malaria vector mosquito life cycle has four stages.
C The malaria vector mosquito needs to feed on blood to develop its eggs.
D The adult female mosquito lays eggs only once in its life time.
E The stage that hatches from the eggs is the pupae.
A is false. The malaria vector mosquito lays its eggs on water surfaces (not grass).
B is true. The malaria vector life cycle has four stages: eggs, larvae, pupae and adults.
C is true. The mosquito needs to feed on human or animal blood to develop its eggs.
D is false. The adult female mosquito lays eggs several times in its life cycle.
E is false. The stage that hatches from the eggs is the larvae.
SAQ 5.6 (tests Learning Outcome 5.5)
List two characteristics that illustrate how the Anopheles larvae are different from other mosquito larvae.
Two characteristics that distinguish the Anopheles larvae from other types are:
- It has no breathing siphon.
- It rests parallel or horizontal to the water surface.
SAQ 5.7 (tests Learning Outcome 5.6)
You know that the parasite needs 10 days to develop inside the mosquito body. Therefore the mosquito needs to live at least 10 days to be able to transmit the infection. 10% of the mosquitoes live more than 10 days in February and more than 20% of them live more than 10 days in September.
- a.Do you expect malaria transmission to occur during these two periods?
- b.During which period will the incidence of malaria be higher?
- a.Yes; the 10% of mosquitoes living more than 10 days will have the potential to transmit malaria.
- b.Malaria transmission will be higher in September because a larger percentage of mosquitoes live more than 10 days during September.
Summary of Study Session 5