Choose the measure from the list that best fits each situation…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Choose the measure from the list that best fits each situation.
- (i) Emptying coolers and pots every week.
- (ii) Introducing Gambusia fish in ponds.
- (iii) Boiling or filtering drinking water, and washing the hands before eating.
- (iv) Fitting wire mesh to doors and windows.
- (v) Not sharing towels and combs.
- A town wants to stop typhoid and amoebiasis.
- A town wants to reduce the larvae in a large pond.
- A family has many cases of ringworm.
- A colony has dengue, which is spread by a mosquito that breeds in clean water in containers.
Need a reminder? The key ideaShow
Amoebiasis is caused by a protozoan, ascariasis by a roundworm, filariasis by a filarial worm and ringworm by fungi. Prevention is by personal hygiene, public hygiene, control of vectors and vaccination. A population grows by a fixed factor each week, and cleaning removes a share of the sites.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) (iii). Both diseases spread by contaminated food and water.
Step 2. (b) (ii). Gambusia eat mosquito larvae.
Step 3. (c) (v). Ringworm spreads by soiled towels, clothes and combs.
Step 4. (d) (i). The Aedes mosquito breeds in clean water in containers, so emptying them every week removes its breeding places. Wire mesh (iv) also helps to keep mosquitoes out.
Answer: (a) (iii); (b) (ii); (c) (v); (d) (i), with (iv) as an extra help.
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