1. Developing World Disease
Malaria – causes and effects

2. Background
Malaria is an infectious disease and is found mainly in the world’s poorest tropical areas, such as Africa, South America and South East Asia.
The disease affects 400 million people and kills two million every year, half of them being children.
A child dies every 30 seconds
90% of all cases occur in Africa.

3. In your jotter, describe, in detail, the distribution of malaria

4. Predominantly a disease of the tropics – endemic disease (always present)

5. However, it is spreading …

6. Causes – Transmission
Caused by a tiny parasite in a person’s bloodstream.
Parasite enters a person’s bloodstream when they are bitten by a carrier mosquito.
Only the female anopheles mosquito spreads malaria.
It bites an infected person and sucks blood containing the parasite into its stomach.
Parasite then multiplies in the mosquito’s stomach.
Mosquito then bites someone else and the parasite enters the new victim on the saliva of the mosquito.
Mosquito is unaffected

7. Physical factors
Mosquito needs day time temperature above 16⁰C all year round – this is why they are found in tropics
Areas of shade – to digest blood eg vegetation and buildings (white walls are attractive)
Stagnant water surfaces – to breed and lay eggs, eg lakes, puddles, ditches, marshes, craters etc
Abundance of rainfall – areas with dry seasons limit mosquito

8. Breeding ground

9. Human factors
Concentrations of population – esp with a low resistance to malaria eg new immigrants
- poor nutrition and health care also help
Low levels of health education and awareness – people less likely to know the risk, how to prevent spread and know the signs of illness

10. HEP schemes – dams slow down river flow, with reservoirs providing breeding grounds
Irrigation schemes – provide ditches, ideal for breeding
Paddy field/terrace agriculture – provides flat land for water to sit, and concentrations of people as a food reservoir
Misuse of pesticides – mosquito becomes resistant eg DDT
Misuse of drugs – mosquito resistance

11. Breeding grounds

12. Several days of headaches and vague, flu-like pains of the body…
INFECTION
Several days of headaches and vague, flu-like pains of the body…
Sweating stage patient soaked in sweat, but begins to feel better after hours…
Several days of weakness and slow recovery
Sudden onset of cold stage – patient shivers violently and turns blue with cold, even though his actual temperature is rising. Lasts about one hour…
Hot stage – high temperature, headache, sickness and dizziness. Lasts several hours…

13. 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.

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

15. Areas that have malaria also suffer economically.
In areas where malaria occurs, many people will have the disease.
As a result, the amount of wealth (from farms and factories) that the area produces is seriously reduced because many people are too sick to work.
At the same time a lot of time and money has to be spent on caring for all the victims.
EXAMPLE:-In the Philippines in SE Asia, when malaria was rife in the 1940s, 35% of the working population was absent from work because of the disease.
– Cheryl and malaria

16. Past paper style question
Explain the physical and human factors which have led to the spread of malaria in the tropics 6 marks

17. Model answer
The physical factors which have led to the spread of malaria in the tropics are that temperatures are above 160C and there is an availability of still water surfaces that can be used as breeding grounds. Human factors include the building of dams and production of irrigation channels provide breeding grounds thus increasing the incidence of malaria. Increased migration increases the spread of the disease to other countries.

18. Explain the methods used to control Malaria
Anti-malarial drugs kill blood parasites (1) Chloroquine is an example of this.(1) Insecticides, such as malathion destroy the female anopheles mosquito (1). Draining all breeding areas eradicates larvae (1), planting eucalyptus trees to soak up moisture removes breeding ground (1). Water can also be released from dams to drown immature larvae (1). Mustard seeds can be used to drag larvae below the surface to drown them (1). Small fish can be introduced to eat larvae and provide a cheap protein source (1). Genetic engineering of sterile male mosquitoes reduces mosquitoes (1). Health education teaches people about how to protect themselves from being bitten (1). Preventative bed nets are cheap and effective at stopping mosquitos biting at night (1). New treatments have also been developed which seem to be more effective such as artemesinin/ACT because malaria parasite is not yet resistant to them (1)

19. Explain the impact on people and the countries affected by Malaria
Malaria happens when the parasites injected into the bloodstream by mosquitoes migrate to the liver, multiply and break out in a new form to attack the red blood cells (1); this causes the victim to become seriously ill and if not treated can result quickly in death (1) Symptoms usually start after about a week to 10 days and can include fever, shaking, chills, sickness, vomiting and muscle pains (1). Children under 5 are often worst affected because they have built up less resistance than adults (1); malaria can recur and so people may often experience several bouts of illness (1); this has a very serious economic effect on their families as if they cannot work they may lose income (1); as a result, families may not be able to afford to send their children to school, so they lose out on education (1);
their income may be so low that they cannot afford sufficient food and so malnutrition and hunger can also be a problem (1); crops may be left unharvested in the fields because farm workers are too ill to gather them in (1); The whole economy of a malaria affected country can suffer because of low productivity, as much of the workforce is frequently off sick (1); few tourists want to visit the country because of the threat from malaria, further hitting the country economically (1).