Higher Geography Malaria

Background The name comes from the Italian mal (bad) and aria (air). It was originally though that 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 on the increase After dropping steeply between 1930 and 1970, malaria is now making a real comeback, especially in Africa, south of the Sahara, where 90% of all deaths occur.

What patterns of malaria distribution can you see from the map above? What factors might explain these patterns?

Infection You can catch Malaria from: Blood transfusions. Infected needles. Intra placentally i.e. from a mother to the baby in her womb. But by far the most common way is by being bitten by the female Anopheles Mosquito.

If the mosquito is carrying the parasite (Plasmodium), then it will transfer it to the victim’s bloodstream in its saliva. If the person is infected, then they will transfer the Plasmodium into the mosquito, which can then fly off and infect someone else.

Mosquito Larvae Mosquito larvae hang from the surface tension of the water, breathing through their siphon tube.

Pupae ready to hatch into Pupae ready to hatch into adult mosquitoes

Mosquito emerges from pupae

Millions of red blood cells are destroyed in an attack of malaria

Falciparum malaria - blood vessels to the brain are blocked with dead red blood cells, starving the brain of oxygen. Coma or death will follow rapidly.

The very young are at risk as they have not yet developed any degree of natural immunity As are pregnant women whose immune system is weakened.

Without rapid medical help, many of these children will die. One child dies every 30 seconds or less in the world from Malaria

Adult victims will have repeated attacks for many years, unless treated. When ill, they cannot work.

Female Anopheles Mosquito

Areas of Stagnant Water

Temperature/ Humidity

Forest Areas

Physical/Environmental Factors The presence of female Anopheles mosquitoes. The presence of the parasite, in either the mosquitoes or human population. Abundant rainfall to provide areas of still/standing water for mosquito to lay eggs. Only a tiny area of water is needed. A warm, humid climate – temperatures between 16°C and 40°C for eggs to develop and hatch. Vegetation nearby to provide shade for the mosquito to hide during the day and digest the blood meal from the night before.

Poor water supply and sanitation

Blood Meal

People out at work

Malaria – Human Factors People nearby to provide reservoir of blood. Houses provide shade where blood meal can be digested. Poor water supply and sanitation leads to water areas where mosquito can lay eggs. Irrigation systems, padi fields and reservoirs provide stagnant water for breeding. Migrants moving into malarial areas - clearing land, looking for work, refugees etc.

Controlling Malaria We can attempt to control Malaria on 4 key fronts: Attacking the vector (carrier of the disease) - the female anopheles Mosquito. Changing the environment. Attacking the parasite/treat the human. Using preventative measures.

Attacking the Mosquito Chemical Control

Pyrethoid insecticide coated bed nets

Use of petroleum products on breeding grounds

Larvae Eating Fish

Mustard Seeds/Egg Whites

Bti Coconuts

Genetic Engineering

Draining breeding grounds/Planting trees

Anti-malarial drug Treatments

Preventative Measures

Chemical Control - DDT Advantages Cheap and very effective in killing the mosquito. Disadvantages Often still too expensive for poor villages. Sprays must be applied repeatedly. They may contaminate water and crops and enter food. DDT was banned globally in Mosquitoes can quickly develop immunity to the spray.

Treated Bed nets Advantages Cheap and very effective in killing the mosquito. Easily available to large numbers of the population. This method has led to huge reduction in cases and deaths from Malaria in countries like Vietnam. Disadvantages Bed nets need to be retreated in order to be effective.

Petroleum products on breeding grounds Advantages Effective in killing the malaria larvae. Disadvantages Pollutes water. Health implications. Whole ecosystems can be harmed

Larvae-eating fish Advantages No harm caused to the environment. Adding fish can clear a pond of larvae in a day. Larvae-eating fish – useful source of protein in people’s diet. Disadvantages Could potential change the eco-system in the ponds and breeding grounds and this could affect other animals.

Mustard Seeds/Egg Whites Advantages A more environmentally friendly method. They do little harm to other aquatic life. They are cheap and easily available. Disadvantages Wasteful to use a valuable source of food like eggs. Impractical to manage as it is difficult to cover vast areas with egg whites in particular.

Bti Coconuts Advantages Cheap to produce. Environmentally friendly bacteria which is harmless to livestock and humans. 2/3 coconuts will ‘control’ a typical pond for up to 45 days. Disadvantages Coconuts could be used a valuable food resource.

Genetic Engineering Advantages Lab stage looking good but not done yet with most deadly strain of malaria. Disadvantages Arguments against genetic modification of species and the future problems it might cause

Draining breeding grounds Advantages This is effective in reducing numbers and can be done with the vast amount of labour available. Disadvantages Impractical as mosquitoes only need a small area of stagnant water so can use puddles, tin cans full of water etc. It is impossible to drain all potential sites. Irrigation and padi fields are essential for food supply.

Anti-malarial drugs Advantages Easy to use, relatively cheap but becoming ineffective in some areas as mosquitoes develop resistance to it. Disadvantages Newer drugs such as Malarone are very expensive.

Preventative Measures Advantages Prevention is better than cure and could save many lives in the long run. It is thought that 30% of child deaths could be avoided, for example, if children slept under treated nets. Disadvantages Huge sums of money are needed to develop and implement education campaigns. ELDC’s simply don’t have the funds and resources available to allow them to do this.

Benefits of controlling the disease for ELDC’s Saving money on health, medicine, doctors, drugs etc. Healthier workforce, increasing productivity. Reduction of national debt. Longer life expectancy. Decreased infant mortality rate. Scarce financial resources could be spent on other areas such as education or housing. More tourists may be attracted if there was less risk of contracting malaria. This could lead to more job opportunities, foreign currency earnings and increased prosperity.