Factors Contributing to Diffusion (DP IB Geography)

Revision Note

Geographic Factors Contributing to Diffusion

Geographic Factors Contributing to Diffusion 

  • Diffusion of disease is its spread from place to place

  • The disease incidence rate is the number of new disease cases over a specific period, in relation to the overall population of an area

  • Geographic factors are physical and human characteristics that affect incidence and diffusion rates 

    • Vector-borne disease transmits to humans from another vector e.g. animals like mosquitos or tics

      • These include diseases such as dengue fever, malaria and Lyme disease

    • Water-borne diseases result from poor sanitation, hygiene and the consumption of unsafe water

      • They include cholera, typhoid, diarrhoea and dysentery 

Physical 

  • Warmer climates, like tropical latitudes, make it easier for vector-borne diseases to spread

    • Mosquitos thrive in warm and humid environments 

    • Climate change is likely to worsen this, as vectors may spread to areas such as southern Europe

  • Heavy rainfall can cause flooding, leaving behind large areas of stagnant water

    • Vectors thrive in these stagnant water bodies e.g. mosquitos 

    • For example, water may stand near populated areas or in irrigation channels

  • Natural disasters could increase dirty water

    • Flood or tsunami waters may contain sewage 

    • Earthquakes or hurricanes can damage sewage systems, allowing sewage to enter drinking water sources

  • Rich biodiversity causes dilution of vector-borne diseases

    • With human-induced climate change, biodiversity will decrease

    • This will increase disease spread

Economic/political

  • Less developed countries have poor sanitation and hygiene, which increases the risk of water-borne diseases 

  • Education rates are also lower, with little knowledge about hygiene and disease spread 

  • Less developed countries also have poorer quality healthcare, e.g vaccines

  • War and conflict can result in higher disease incidence:

    • Destruction of healthcare infrastructure, like hospitals 

    • Damage to sewage pipelines, resulting in contaminated water 

    • Debris contamination in stagnant water

  • Industry development may also cause diffusion:

    • Logging within tropical rainforests increases temperatures in the area

      • Heavy rainfall causes flooding of the cleared/deforested land or increases

    • Water collects in mining pits, irrigation channels and rice paddy fields, where vectors breed more efficiently 

    • Agriculture (e.g. livestock) can provide food for vectors, increasing their population

Social and cultural

  • Migrants or settlers may move to an area that already has high immunity and contract vector-borne diseases

  • Urbanisation causes increased unregulated development in areas where vectors thrive or where other non-human disease hosts exist

  • Globalisation has meant that new non-indigenous vectors can move around the world

Impacts of Vector-borne & Water-borne Diseases

Demographic

  • Water-borne diseases heavily impact children, causing higher mortality rates in younger people

  • Vector-borne diseases like malaria heavily impact children and pregnant women 

    • Malaria impacts Maternal Mortality rates

  • Immunocompromised people have a higher risk of contracting malaria e.g. HIV

  • Diseases impact travellers, as they haven’t been exposed to the disease and have no immunity e.g. malaria

  • Lower-income groups/those in poverty are more at risk of vector and water-borne diseases

    • Many developing countries lie in warmer/tropical regions, where vector-borne diseases thrive

    • Poor sanitation and unsafe water increases the risk of water-borne diseases 

  • Both vector-borne and water-borne diseases can impact death rates in a country

World map showing vector-borne disease deaths with Africa having the highest rates, followed by South America, parts of Asia, and some regions in North America.
Deaths from vector-borne diseases

Socio-economic

  •  In lower-income countries, people travel far to collect safe water, usually by foot

    • It may take a long time to get to the water source

    • This can mean they do not go to work, which can negatively affect the economy 

    • They may suffer physically as a result of strenuous activity

  • Disease prevention programmes can be costly

    • This can include bug nets or repellants and medical fees

    • This can cause problems for lower-income countries, which already struggle with economic development 

  • Children may not be able to attend school due to sickness, reducing education rates 

  • The tourism industry may take a hit. Foreign travellers may be wary about entering a country e.g. the Caribbean and Latin America experienced large losses in the tourism industry after the Zika virus hit in 2015

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