Biological Disease (AQA A Level Geography)
Revision Note
Written by: Robin Martin-Jenkins
Reviewed by: Bridgette Barrett
Prevalence & Distribution of Malaria
Prevalence, Distribution and Seasonal Incidence of Malaria
Malaria is a communicable (infectious) disease found in tropical areas
It is biologically spread by disease vectors - parasites carried by female mosquitoes
Prevalence means the proportion of a population who have a specific characteristic in a given time period
Nearly half of the world’s population is at risk of malaria
In 2020, an estimated 241 million people contracted malaria in 85 countries, killing around 627,000 people
Infants and children under 5 years of age, pregnant women and patients with HIV/AIDS are most susceptible to dying from severe malaria
Migrants, mobile populations and travellers are also vulnerable if they enter areas with intense malaria transmission
Some adults in areas where malaria is common will develop partial immunity which reduces the risk that malaria infection will cause severe disease
Distribution refers to the pattern of health events in a population
Seasonal incidence of malaria depends on physical factors
Greatest incidence of the disease occurs during and soon after the season of highest rainfall
Due to mosquitoes breeding in stagnant water supplies
Malaria can be present throughout the year in equatorial regions where seasonal variations are less marked - known as ‘malaria endemic’ areas
E.g. Central African belt of the Congo basin, including parts of Equatorial Guinea, Cameroon, Congo, Democratic Republic of Congo, Rwanda, Uganda and Kenya
Examiner Tips and Tricks
When revising, try and learn some specific countries or regions where malaria is most prevalent. For example, rather than just saying it is found in Africa, be more specific with where in Africa.
Malaria & its Impact
Impact of Environment on Malaria
Links to Environment | Impacts on malaria transmission |
---|---|
Physical |
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Socio-economic |
|
Impact of Malaria on Health and Well-Being
Malaria affects people’s quality of life and their physical, mental and economic well-being
Examiner Tips and Tricks
A 9 or 20 mark question is likely to ask you about more than one section of the topic. Make sure you are able to assess why malaria occurs in certain places and also how it impacts on people’s way of life. You would be expected in these questions to come to a view as to which causes and impacts are most severe, which might depend on which examples you use.
Management & Mitigation of Malaria
Management and mitigation strategies include:
Giving antimalarial drugs and vaccines to those living or travelling to areas of transmission
Seasonal malaria chemoprevention (SMC) - a programme that delivers antimalarial medicine to vulnerable populations during peak malaria transmission season whether or not the recipient is infected with malaria
Treating sick people quickly by making diagnosis tests quicker, more accurate and more widely available
Vector controls
Insecticide-treated mosquito nets (ITNs) given to vulnerable communities
Indoor residual spraying (IRS) - the spraying of insecticide on surfaces within homes to repel mosquitoes
These strategies have helped reduce malaria transmission significantly
In 2000, 6 countries in malaria transmission zones had fewer than 100 cases. By 2020 that had increased to 26 countries
But IRS and antimalarial drugs are expensive and less available to populations in remote rural areas, where they are often most needed
Insecticides can have negative knock on effects:
People’s health - some have been linked to cancer and miscarriages in pregnant women
Death of insects and fish in local water ecosystems
There is evidence from Vietnam, Cambodia and Thailand that mosquitoes are developing resistance to insecticides so that they are becoming less effective
Research is needed to develop new varieties to outpace the resistance
Examiner Tips and Tricks
Look out for questions that ask you to assess the management strategies of the diseases you have studied. You should try and explain how successful any of the strategies have been as well as pointing out any limitations. For example, the drugs used to treat malaria are effective but can be expensive and so not all people in poorer parts of the world will be able to afford them without help from governments or NGOs.
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