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Development & Health
Malaria
The female Anopheles mosquito
When the Anopheles Mosquito “bites”, it actually sinks a long, thin mouth part, the
proboscis, into the skin.
The mosquito then pumps saliva under the skin, to stop the blood clotting – so that it can drink
uninterrupted! In the saliva is the main culprit, the Plasmodium, a single-cell blood parasite.
Malaria distribution
breedingMosquitoes breed
in any stagnant water
flooded rice fieldspuddlestin cans
Ideal breeding grounds for mosquitoes – still,
shallow water.
Mosquito larvae at the edge of a pool.
Mosquitoes will breed in small puddles, even in animal hoof prints, empty cans
and bomb craters.
A high risk area – people, vegetation cover and standing water during the wet season.
Collecting water, an essential fact of life for millions of people, poses real risks of being bitten. However, you cannot catch the disease by drinking water containing larvae.
Mosquito larvae hang from the surface tension of the water, breathing
through their siphon tube.
Sampling larvaeScientists are
sampling larvae in order to target spraying
A jar containing mosquito larvae.
An adult emerges, the males to look for plant nectar, the females for blood.
Most at risk are the very young, who have not yet developed any degree of
natural immunity…
…along with pregnant women, whose immune system is weakened.
Posters are used to educate people about the disease and its symptoms
3 Areas of Control
Against the adult mosquito;
Against the eggs and larvae;
Against the Plasmodium, by treating victims.
1. AGAINST ADULT MOSQUITOES
INSECTICIDE TREATED BED
NETS(VERY SUCCESSFUL)
GENETIC ENGINEERING
(VERY LIMITED SUCCESS)
DDT
MALATHION
STERILE MALES
KILLER MALES
INSECTICIDE SPRAYS
(SUCCESSFUL…BUT)
Insecticide sprays are very efficient, but there are several drawbacks:
1. They are relatively expensive, often beyond the means of poor villages;
2. Sprays must be applied repeatedly for long-term effectiveness.;
3. They may contaminate water and crops.
4. Most importantly, mosquitoes can quickly develop immunity to the spray.
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.
A simple mosquito net may mean the difference between life and death…
…even better if they are dipped in insecticide, as in this Kenyan village. The normal chemical used for ITNs (Insecticide Treated Nets) is Permethrin, which is harmless to humans, but deadly to mosquitoes. Several African countries are trying to get more people to use these nets, by removing tax on them, reducing their cost.
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
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.
BIOLOGICAL CONTROL
Adding larvae-eating fish, such as the Muddy Loach, to padi fields and pools, can clear them of larvae within a day.
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
BIOLOGICAL CONTROL - Bti
You can even buy Bti over
the counter in the U.S.
3. AGAINST THE PLASMODIUM… 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.
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.
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.
..AGAINST THE PLASMODIUM3. 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.
VACCINATION
At the moment, there is no effective vaccine against malaria, although
scientists all over the world are trying to develop one.
The search goes on to try to find a vaccine:
the Bill Gates Foundation recently donated more than
$168 million towards malaria research,
most of that to find an effective vaccine available to all.
Mosquitoes tend to be most active from dusk into the night. Spraying the shaded sides of trees and buildings during the day while they are resting is a common approach to eradication.
Drug resistancePlasmodium
develops resistance to drugs
Artemisinin combination therapy
Artemisinin is a new drug which is effective if used in combination with other drugs.It is believed that resistance is much less likely to develop againstA.C.T.
The use of bed nets
Bed net programme - Malawi
Bed net treatment
BackgroundThe name comes from the Italian mal (bad) and aria (air) – it was originally thought the disease was spread by the damp air from swamps.
The link between the disease and the Anopheles Mosquito was first made by Ronald Ross, a Scottish army doctor, working in India.
Malaria is a disease which is endemic in many countries – this
means it is always present.
It is predominantly a disease of the Tropics.
…with global warming, however, malaria may be closer than you think…