Food systems and spread of diseases

Systems approach to food production


Farming can be described as a system because it consists of inputs, processes and outputs.

Inputs are the materials (both human and physical) needed to operate the farming system. Human inputs include labor, capital, skills, technology etc. Physical inputs are ones provided by nature – land, water, soil, seeds, etc

Processes or throughput  are the main activities that take place on the farm to convert the inputs into outputs. Processes in an agricultural systems include ploughing, weeding, sowing, harvesting, milking, etc

Outputs are the products obtained after the inputs are processed in the farming system. They may include products (maize, cattle, meat) cash, manure, animal feeds, eggs, etc.(positive outputs). Others include waste products such as polluted air, water, land etc, including soil erosion (negative outputs). It may include feedback into the system eg. knowledge and experience gained in farming, cash from the sale of a product or inputs from the products obtained from the farm.

The diagram below is a summary of farming as a system:

Souce: Geography, An integrated Approach by David Waugh
Farming as a systems: Source – David Waugh, Geography, An Integrate Approach

Farmings systems can either be intensive or extensive system. Extensive systems use small labor inputs, small capital inputs and depend largely on natural inputs such as rainfall and natural fertility of the soil. They are characterised by small labour force on large farms with less technology or machinery involved in the processes. The output is usually low. An example is rice farming in India. The motive is to feed the farmer and his family and the left over is sold.

Intensive farming systems are the opposite of extensive farms. They use large amounts of capital inputs and small amounts of labour inputs (capital intensive) or small amounts of capital inputs with large amounts of labour inputs (labour intensive). The land size is smaller than that of extensive farming and output is far more greater than extensive farming. The motive is to make profit.

Merit of the systems approach:

Sustainable Agriculture:
The ability of a farm to produce indefinitely without causing harm to the ecosystem/environment. It ensures that resources are used in such a way that future generations can still benefit from it. Sustainable agriculture conserves natural resources, prevents environmental degradation and increases the profitability of the farm

Source: Acqua-alimenta

The Environmental Costs of Increasing Food Production

  • The practice of mono culture by large TNC’s causes significant damage to the natural environment.
  • The use of aggro-chemicals is harmful to the environment.
  • The cost of cleaning up chemical pollution is expensive.
  • It also leads to air pollution and greenhouse gas pollution from the farm. Eg. Methane.
  • It leads to the removal of hedgerows leading to deforestation.

Increasing food production has come at a greater cost to the environment in terms of the use of natural resources as well as man-made resources. e.g. fertilizers, tractors. Man-made resources which rely on energy inputs can be measured by the amount of energy subsidies they use.

Energy subsidies are defined as: “sources of energy not directly received from the sun. eg. Fossil fuels like oil, natural gas and coal. To assess the extent to which a particular agricultural system depends on energy subsidies, the energy efficiency ratio (EER) is calculated. For example, in a poultry farm,  the poultry is dependent on shelter, heating, automatic feeding and watering. Such a farm would consume more energy inputs/subsidies than an arable farm.

Energy Efficiency Ratio
The Energy Efficiency Ratio measures the amount of energy input compared with the amount of output produced by the farm. There are two types of inputs: direct inputs and indirect inputs. Example of the direct inputs include planting, cultivation, labor, machinery, vehicle fuel, farm tools etc. Examples of indirect inputs are fertilizers, electricity, irrigation, transport, pesticides etc. The output-input ratio is calculated by dividing the total output by the total input. An efficient farm should have an EER1.
Energy Efficiency Ratio=total outputs/total inputs.

Image result for Energy efficiency ghana"
A label of energy efficiency for electrical appliances in Ghana 

Factors affecting energy subsidies or energy efficiency Ratio in different environments

  1. Climate: Farms located in warm climates will need less energy than those in cold climates because colder ones need artificial light for crop growth.
  2. Type of soil: Loamy soil requires less fertilizer. Sandy soil requires more fertilizer.
  3. Type of crop cultivated: beans do not use a lot of nutrients. They fix nitrogen into the soil. Crops that produce protein require a lot of energy.
  4. Relief/topography: When the land is relatively flat, it needs less energy, because it retains water and minerals easier.
  5. Irrigation.
  6. The type of farming system: labor intensive or capital intensive.

One obvious critique of the EER as in indicator of the sustainable of a particular farming system is with its narrow focus – it neglects the wider environmental impacts of the farming system on soil quality, water resources and long-term conditions of the natural environment. It therefore doesn’t address the wider sustainability issues.

It is, however, a useful method for examining the overall efficiency of energy used within a farming system, and this is particularly relevant in the context of climate change.

Reasons why energy efficiency ratios vary within a country or region.
Energy ratios depend on numerous factors, including

  • the technology employed in agriculture (e.g. glasshouses are much less efficient than open field farming);
  • methods of cultivation (generally, subsistence farming is more energy-efficient than commercial farming);
  • the precise crop(s) grown (e.g. growing peas has a higher energy ratio but its subsidies will be lower than growing wheat or maize);
  • the climate (energy ratios are often more efficient in warmer, wetter areas, than in cooler, drier areas, because of
  • differences in biological productivity);
  • the soil type (which also results in different yields or levels of productivity).


Source: IBO

Water footprint is the amount of water needed to produce food in an agriculture system. It is also known as embedded water. This has been extensively treated under Impacts of changing trends in resource consumption

The physical and human processes that can lead to variations in food consumption

Food consumption per capita is increasing worldwide. This is partly due to the growing number of people joining the new global middle class. This is mainly due to physical and human processes that have led to an increase in food production and consumption. Notwithstanding this increase, there are occasional food shortages in many part of LICs, especially Sub-Saharan Africa, due to physical and human causes.

Research has shown that climate change and its related factors can cause food shortages. This physical process is known Food Availability Deficit (FAD). Again, according to Sen (1981), food shortages could be the result of human (political and economic processes) which makes it difficult for people in hunger stricken countries to have access to food. This is called Food Entitlement Deficit(FED).

It is interesting to note that improvements in these processes –  physical (climate change) and human (political and economic) have improved in some parts of the world, resulting in increased food production and subsequently, increased food consumption.

There are two main improvements in physical processes that have led to an increase in food production and ultimately, food consumption:

a) Increased amount of farmland  through converting brownfield sites and water logged areas to farm lands and cultivating forested areas. This has led to an increase in the amount of farm lands in Africa, Asia and other parts of the developing world.

b) The second reason is an increase in productivity, due to increased land size. Increase in agricultural productivity is the result of:

The human processes, including

  • high yielding variety of crops such as IR-8 rice and wheat. These crops have been genetically modified to increase the amount of output per hectare.
  • Mechanization of agriculture has made it possible for a small amount of land to be cultivated for farming.
  • Use of chemical fertilizers. Despite its environment impact, the use of agro chemicals have led to an increase in the amount of crop yield per land.
  • Irrigation has not only resulted in an increase in the amount of land needed to cultivate food, it has also enable experiencing seasonal rainfall to undertake dry season farming.

Other factors include:

  • rising incomes, leading to an increase in the demand for food and meat in MICs;
  • improved transportation, leading to an improvement in the distribution of food to areas experiencing food shortages
  • better education, resulting in better food choices in favor of high quality food.
  • Mass media also plays a crucial role in determining the amount of food consumed by people in developed countries and urban areas. This is also partly related to income and they type of occupation, which determines food choices or dietary habits.

The importance of Diffusion in the spread of Disease and agriculture innovations

Diffusion is the spread of something more widely. This spread can be related to disease diffusion or the diffusion of agriculture innovations. Disease/agriculture innovation diffusion can be classified into a number of types.

  1. Expansion diffusion. Expansion diffusion occurs when a disease or agriculture innovation spreads from one place to another. In this expansion process, the disease/innovation often intensifies in the originating region. However, as the disease/innovation expands into new areas, it is likely to weaken. This type of diffusion was recognized in the recent H1N1 flu that had its source in Mexico.
  2. Relocation diffusion. Relocation diffusion is a spatial/geographic spread process, whereby the disease/innovatoin leaves the areas in which it originated as it moves into new areas. An example is the migration of people with HIV or Measles. The spread of cholera in Haiti in 2010 was thought to be brought into the country by aid workers from Nepal.
  3. Network diffusion. Network diffusion occurs when the disease/innovation spreads through transportation and social networks. An example is the diffusion of HIV which spread along important transport routes in Southern African countries with developed road networks, as well as social (sexual) networks. Second and third examples are the recent H1N1 flu virus and Ebola virus which quickly went global via the aviation network of flights and major international airports.
  4. Contagious diffusion. Contagious diffusion spread depends on direct contact. This is mostly applicable to disease diffusion. It is a type of diffusion whereby the process is strongly influenced by distance, because nearby individuals or regions tend to have a much higher probability of contact or infection (incidence of the disease) than remote individuals or regions.
  5. Hierarchical diffusion. It involves the spread of disease through an ordered sequence of classes or places, for example from large cities to remote villages. Cascade diffusion is a term used to describe a process assumed to be downwards from larger cities to smaller centres.

The diffusion of disease/agriculture innovation is likely to be affected by distance; places closer to the source of the disease are more likely to experience a higher rate of diffusion and vice-versa. This is known as the distance-decay-effect.

Concept of barriers in diffusion:

Barriers of disease diffusion can be classified in terms of:

Natural/physical barriers. The most important natural barrier is that of

  • Distance decay. The further a place is away from the source of incidence the lower the incidence of disease.
  • Rural peripheries are likely to affected by the spread of certain diseases as a result of the remoteness of the rural area and the unlikely event that many people will be affected by the disease, which lowers possibility of diffusion.
  • Mountainous regions. Mountains and oceans also act as major natural barriers to the spread of disease as they contain people and restrict migration
  • Regions of extreme climate experience relatively small amounts of in and out-migration. As a result the spread of disease into these regions is less likely.

Human measures relate to

  • socio-political structures such as political borders and migration control, which restrict or prevent the movement of people. US migration policy specifically prevents the immigration of foreigners who carry infectious diseases. At times of high risk borders can be completely closed, however for the economic impacts of such a measure it would need to be an extreme case.
  • the management of disease and directly related to the way in which a disease is transmitted. In the case of the H1N1 flu virus many measures were adapted in the UK. Initially, people who contracted the flu were isolated in their homes. This later became a bit of a farce as these same people were giving media interviews from their house windows. Isolation is of course an important management measure for many diseases though, and is essential for highly infectious diseases such as cholera.
  • Other measures in the UK involved creating heightened awareness of improved hygiene. People were advised to refrain from typical greeting customs such kisses and hand shakes and to wash their hands carefully. In public places like airports and railway stations people wore face masks. In Catholic ceremonies people refrained from drinking directly from the chalice during the celebration of the Eucharist. Finally, authorities considered cancelling larger public events such as sports events and pop concerts. These events at the time all saw reduced attendance.

Source: Codrington, S. Our Planet’s Food and Health, Solid Star Press, 2017

Geographic factors contributing to the incidence, diffusion and impacts (demographic and socio-economic) of vector-borne and water-borne diseases

  1. Malaria

Key facts about malaria

  • Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable.
  • In 2017, there were an estimated 219 million cases of malaria in 90 countries.Malaria deaths reached 435 000 in 2017.
  • The WHO African Region carries a disproportionately high share of the global malaria burden.
  • In 2017, the region was home to 92% of malaria cases and 93% of malaria deaths.Total funding for malaria control and elimination reached an estimated US$ 3.1 billion in 2017. Contributions from governments of endemic countries amounted to US$ 900 million, representing 28% of total funding. ( Source WHO)

Question: Describe the geographic factors affecting the incidence, diffusion and spread of Malaria.

Geographic or environmental factors
Geographic factors include physical/environmental, economic, social, political, social and cultural considerations that can either cause an increase in the number of people affected by the malaria, or the general spread of the disease in a given area.

Physical factors

  1. Tropical conditions. These include areas such as Sub-Saharan Africa, Brazil, Colombia, Ecuador, Malaysia, Singapore, Papua New Guinea, and all the countries that lie 23.5⁰ north and 23.5⁰ south of the equator.

Characteristics of tropical conditions:

  • High temperatures of about 20⁰C, allowing it complete its life-cycle
  • High humidity, leading to dampness
  • High rainfall leading to stagnant waters in estuaries, deltas, irrigation channels, densely populated areas, etc
  • Enclosed spaces can also breed mosquitoes.

Human factors

  • Logging in the tropical rainforest. Logging is the cutting down of trees. This can help in the spread of mosquitoes. It modifies the physical conditions by increasing the temperature of a given area, providing good conditions for mosquitoes to thrive. It leads to the creation of stagnant waters because it will expose the forest to heavy rainfall, which can cause flooding or an increase in water collected in lakes and rivers.
  • Mining. Mining leads to the clearance of the forest and the digging of pits, where water can be collected and stagnant for several days, thereby leading to the breeding of mosquitoes
  • Agricultural projects such as irrigation. Water can be collected in canals for days, and paddy rice fields, which provides a breeding ground of mosquitoes.

Social factors

  • War and conflict. When there is conflict or war, sanitation in urban areas becomes poor because people would have migrated out of conflict zones, thereby leaving gutters choked with debris which can collect stagnant water.

Demographic factors

  • Mass migration of people

Impact of Malaria

  • It is very expensive to the individual, household and government. According to the WHO, total funding for malaria control and elimination reached an estimated US$ 3.1 billion in 2017. This includes the cost incurred in preventive measures such as bed nets, mosquito repellents, fumigating the environment as well as cost of doctors’ fees, public education etc. This can be an economic drain to the individual and the government.
  • Loss of productivity for employers. According to WHO, 200 million dollars in productivity was lost from 2005 to 2010 due to malaria. Malaria can cause people to make mistakes in the workplace, loss of work hours, increased medical bills.
  • It can negatively impact children’s education by disrupting the number of days they spend in school due to absenteeism as a result of malaria.
  • Leads to loss of government revenue especially in the tourism industry since many tourists will avoid visiting tourist attractions with a lot of mosquitoes due to the fear of contracting malaria.

Prevention Strategies

a. Protect humans from mosquito attacks

  • The use of insecticides e.g. DDT, which has been effective in countries like Ecuador, Ethiopia, Thailand. However, there are negative consequences on water pollution and the effects on the food-chain.
  • Antimalarial drug treatment can be used to prevent malaria, especially for travelers from non-malarial regions such as Europe and Americas.
  • Distributing Long lasting insecticidal mosquito nets for free to people living in malaria prone areas
  • Public health education of population living in malaria endemic regions.
  • RTS,S is the first, and to date, the only vaccine that has demonstrated it can significantly reduce malaria, and life-threatening severe malaria, in young African children. Beginning in 2019, 3 sub-Saharan African countries – Ghana, Kenya and Malawi – led the introduction of the vaccine in selected areas of moderate-to-high malaria transmission as part of a large-scale pilot programme coordinated by WHO. The aim is to vaccinate about 360 000 children per year in the selected areas across the 3 countries. Vaccinations are being provided through each country’s routine immunization programme (WHO).

b. Reduce mosquito population

Kill the mosquito larvae by interrupting its life cycle by

  • Covering open water tanks
  • Covering stagnant waters
  • By infilling redundant irrigation channels
  • Ponds and lakes should be stocked with fish to eat the larvae.
  • Spray the tops of stagnant waters with oil

Treatment of malaria

The best form of treatment for P. falciparum malaria is coartem and the use of other Artemether-lumefantrine based drugs. However, these days, most parasites have developed resistance to these drugs and a combination of other malarial drugs have often been recommended by doctors.


Examine the strengths and limitations of the energy efficiency ratio as an
indicator of sustainable agriculture. [10]

Energy efficiency ratio is a measure of the amount of energy input into a farming system compared with the energy outputs. A ratio of greater than 1 is considered efficient, as outputs will be greater than inputs. Inputs into the system include labour, machinery, pesticides, fertilizers, irrigation and fuel, while outputs refer to the quantity/yield of food that is produced.

Energy efficiency ratios differ for many farming systems around the world.
Capital-intensive systems, such as irrigated rice farming, are likely to have high
inputs and high yields, and might be considered as efficient. Subsistence
farming systems, with high inputs of labour, might also be regarded as efficient if the outputs are high.

Farming systems differ in their EERs and their relative sustainability. EER might
be a good indicator of the efficiency of a farming system, but it neglects the wider environmental and social impacts of farming. Agricultural systems that have a high EER might produce plentiful food supplies, but they are not necessarily sustainable. The farming system might have an adverse impact on the land or water – for example, irrigation might lead to salinization and depletion of groundwater; pesticides might result in eutrophication, and soil quality might be degraded

Source: IBO