2. Controlling malaria.
• When trying to control malaria there are three main
approaches that you can take:
• Control against the adult mosquito
• (stopping people from being bitten by them)
• Control against the eggs and larve
• (to stop the adult mosquito from being born)
• Control against the plasmodium
• (by treating people)
4. Insecticide sprays
• This is when the chemical
DDT is sprayed on the
walls of homes.
• This is the most widely
used method and it is
recommended by the
WHO.
• Sprays must be applied
repeatedly for long term
effectiveness.
5. Insecticide sprays
• DDT is unfortunately
poisonous to humans.
• It can get into water
supplies and can be
passed on to young
children through breast
milk.
• Even though it is cheap
very poor villages can not
afford to pay for this
treatment.
• MOST IMPORTANTLY:
• The mosquitoes can
quickly become immune to
the chemical making the
spraying worthless.
6. • The effect of stopping the use of DDT in Sri Lanka (Ceylon). Was the
banning of DDT one of the costliest mistakes of all time?
• One estimate suggests that 50 million children have died of malaria
since the use of DDT was greatly reduced in the 1960s.
7. Effectiveness of DDT
• There is no denying that DDT can be effective as the
graph on the last slide highlighted.
• Also there was around a 60% drop in cases of malaria
when D.D.T. was introduced to Ecuador in 1993 and a
90% increase when it was withdrawn from Bolivia in
1993.
• Overall it is a good method but can’t halt the spread of
malaria entirely.
9. Mosquito net
• Mosquito nets are a great
way to combat the spread
of malaria.
• First of all they physically
stop the mosquito from
landing on you when you
sleep and feeding.
10. Mosquito net
• The women in this picture
are treating the mosquito
net with insecticide.
• The most common
chemical to use is
Permethrin, which is
harmless to humans, but
deadly to mosquitoes.
11. Mosquito net
• This is a very popular way
of combating malaria with
the charity “Roll back
malaria”
• It can be extremely
effective but it is up to
three times as expensive
as DDT.
• Several African countries
are endorsing this method
and removing tax on the
nets.
12. Genetic engineering
• Labs produce sterile male mosquitoes so that the breed
die out.
• This is very time consuming and it can not be replicated
on a large scale.
13. 2. AGAINST EGGS AND LARVAE
PHYSICAL CHEMICAL BIOLOGICAL
DRAINING
BREEDING
SITES
FLUSHING
BREEDING
SITES
PLANTING
EUCALYPTUS
TREES
SPRAYING
WITH
LARVICIDES
ADDING OIL, EGG
WHITES OR
MUSTARD SEEDS
ADDING FISH TO
PONDS AND PADI
FIELDS
ADDING Bti
IN
COCONUTS
14. PHYSICAL CONTROL
Draining breeding places: because
mosquitoes need so little water in which to lay
their eggs, it can be virtually impossible to find
and drain them all.
Flushing out breeding sites by weekly release
of water can drown the larvae, but can only be
done in suitable areas and where there is
surplus water.
Planting Eucalyptus trees to absorb excess
water from the soil helps drain breeding sites.
15. Draining/flooding stagnant water
• In theory this is a good idea. However the scale on which
it would have to be done is too great.
• Pools of water would have to be drained once every 5-7
days as the mosquito breading period is 8-10 days.
• Mosquitoes only need a pool of water the size of a
footprint to breed so it is unlikely that all pools of water
would be drained.
• Also LEDC can’t afford to empty their reservoirs on a
regular basis.
16. • This is very similar to the spraying of DDT but on to the
breeding grounds.
• It suffers from the same success’ and failures of DDT as
well as the fact that it is unlikely that all pools of water will
be found.
Spraying with Lavicides
17. BIOLOGICAL CONTROL
Adding larvae-eating fish, such as the Muddy
Loach, to padi fields and pools, can clear them
of larvae within a day.
Can you think of
any other
benefits of this
method?
18. Adding larvae eating fish
• Although it is initially expensive it can provide a source of
food for local people.
• Unfortunately it can endanger local wildlife species.
19. A number of techniques can be used
to drown the larvae
20. Drowning Larvae
• Adding mustard seed to the water will drag the larvae
down.
• Spraying the water with egg whites clogs up the
breathing system of the larvae.
• Spraying oil on the water also causes them to suffocate.
After all the problems with effectiveness that we
have looked at what do you think the limitations of
these methods could be?
21. BIOLOGICAL CONTROL - Bti
The bacillus Bti (Bacillus Thuringiensis Israelensis !!!)
can be incubated in coconuts, where it multiplies. The
coconuts are then broken open and thrown into pools,
where the bacilli are eaten by the mosquito larvae. They
kill the larvae by destroying its gut.
Spraying Bti
from a boat
The
incubation
stage
Adding
to
pools
23. 3. AGAINST THE PLASMODIUM…
1.Quinine: Originally
extracted from the
bark of the South
American Cinchona
(Fever Tree), it was
for a long time the
main anti malarial
drug.
An ingredient of Tonic Water (check in the
supermarket), Quinine was often taken with
Gin to mask its bitter taste. However, you
would need to drink about 25 Gin and Tonics a
day to get the recommended dose.
24. AGAINST THE PLASMODIUM…
2. Chloroquine: Now
the most common anti
malarial drug, but, like
Quinine, becoming
ineffective as the
Plasmodium mutates
and becomes immune
to it.
25.
26. ..AGAINST THE PLASMODIUM
3. Artemisia
(Wormwood): Used as an
anti malarial herbal
remedy by the Chinese
for hundreds of years
(known there as
Qinghaoshu), it was
“rediscovered” during
the Vietnam war and may
prove to be a major
weapon in the fight
against malaria, as
plasmodium do not seem
to become immune to it.
27. VACCINATION
At the moment, there is no effective vaccine
against malaria, although scientists all over the
world are trying to develop one.
28. New discovery
• A recent discovery has been made in a vaccine that
claims to half the chances of a human contracting
malaria.
• There is no proven test yet but initial findings are
positive.
• The WHO has admitted the battle against malaria is
currently being lost and the must do more to stop it. It is
clear that the problems will not stop any time soon.
