Microscopic protozoa called plasmodium, which acts as a parasite on its host, cause malaria. Female mosquitoes transmit it and the distribution of these depends a great deal on the physical environment in order for them to flourish. The key contributing factors that lead to the spread of malaria include moisture, warmth, and vegetation cover in order for the mosquitoes to flourish leading to the spread of the disease. Malaria is a deliberating infectious disease characterised by chills, shaking and intense fever. These symptoms often lead to death.
Analysis
Temperature
Malaria needs temperatures of 16°C and above; otherwise the parasite is unable to develop inside the stomach of the mosquito. Above 32°C, the parasite is unlikely to survive. Therefore malaria can only affect certain areas of the globe that provide suitable temperatures. These areas are going to be warmer areas and the disease is unlikely to affect colder regions. However an increase in the tourism industry in warmer places has increased the risk of the disease speeding into areas outside the tropics. Travellers returning from overseas bring about 200 cases of malaria into the UK.
Fig. 2 Annual average temperature (°C) 1997
There is a clear match between temperature and distribution of malaria. When I compare fig 1, which shows the distribution of malaria, with fig 2, I can see that areas with high numbers of malaria cases, lie in regions where the annual average temperature is between 15.5 °C and 30.5 °C.
Latitude & Relief
Countries that lie in higher latitudes experience less or no cases of malaria, as temperatures are lower and do not provide enough warmth for the parasite to develop. For example in the UK malaria cases are very rare as the annual average temperature is very low at 5.5°C. The temperature must be at least 16°C. However in countries close to or on the equator, temperatures are much warmer and provide ideal temperatures for the disease to develop and spread.
Relief within a country plays a massive role in the development & Spread of malaria. For example temperature drop as altitude increases. Therefore a country that possesses the ideal temperature for the parasite to work may not necessarily have cases of malaria in certain areas of that country. These areas with a high altitude will be to cold for the parasite to develop. An example of where this has happened includes the mountain ranges in the tropics.
Inc. Map of Altitude/Relief
Rainfall
Mosquitoes require rain and moisture for them to breed. They tend to lay eggs in lakes and swampy areas. Therefore areas with high precipitation will have higher numbers of mosquitoes and therefore cases of malaria are likely to be more common.
There is a clear match between rainfall and distribution of malaria. There is a clear match between temperature and distribution of malaria. There are very little cases in northern Africa where rainfall is between 0-75.
When I compare fig 1, which shows the distribution of malaria, with fig 2, I can see that areas with high numbers of malaria cases, lie in regions where the annual average temperature is between 15.5 °C and 30.5 °C.
