1. What are the global patterns of disease and can factors be identified that
determine these?
1.a. Diseases can be classified and their patterns mapped. The spread of diseases
is complex and influenced by several factors.
How diseases can be classified, including infectious and non-infectious,
communicable and noncommunicable, contagious and non-contagious,
epidemic, endemic and pandemic.
Infectious vs Non-infectious:
o Infectious: Caused by pathogens (bacteria, viruses, fungi, parasites).
Can spread between individuals (e.g. TB, HIV).
o Non-infectious: Not caused by pathogens. Often chronic or lifestyle-
related (e.g. diabetes, heart disease).
Communicable vs Non-communicable:
o Communicable: Can be transmitted directly or indirectly (e.g. malaria,
cholera).
o Non-communicable: Not passed person to person. Often influenced by
genetics, environment, lifestyle (e.g. cancer, asthma).
Contagious vs Non-contagious:
o Contagious: Spread easily via direct contact (e.g. flu, COVID-19).
o Non-contagious: Still infectious but not spread easily (e.g. malaria—
requires vector).
Epidemic: Sudden increase in disease cases above normal in a specific area
(e.g. Ebola outbreak in West Africa).
Endemic: Constant presence of a disease within a region or population (e.g.
malaria in parts of sub-Saharan Africa).
Pandemic: Epidemic that spreads across countries or continents (e.g. COVID-
19, HIV/AIDS globally).
Patterns of diseases, including global distributions of malaria, HIV,
tuberculosis, diabetes and cardio-vascular disease.
Malaria:
o Mostly in tropical and subtropical regions (Sub-Saharan Africa, SE
Asia, parts of South America).
o Transmission relies on presence of Anopheles mosquitoes.
, o Absent in temperate zones due to cooler climate unsuitable for vector
survival.
HIV/AIDS:
o Highest prevalence in Sub-Saharan Africa, especially Southern Africa
(e.g. Eswatini, Botswana).
o Urban areas in all continents affected.
o Transmission through bodily fluids—sexual contact, blood transfusions,
childbirth.
Tuberculosis (TB):
o High incidence in developing regions: South-East Asia, Africa.
o Often linked with HIV co-infection and poverty.
o Resurgence in urban, overcrowded settings and areas with poor
healthcare.
Diabetes:
o Increasing globally, especially in high-income countries and rapidly
urbanising low-income countries.
o Associated with diet, obesity, sedentary lifestyles.
o India and China have highest absolute numbers.
Cardiovascular Disease (CVD):
o Leading cause of death globally.
o High rates in high-income nations due to ageing populations, poor
diets, sedentary lifestyles.
o Growing prevalence in MICs due to lifestyle transitions.
Disease diffusion and spread to new areas (Hägerstrand model), including the
phases of diffusion, physical and socio-economic barriers.
Hägerstrand's diffusion model (geographer Torsten Hägerstrand):
o Focuses on how innovations (or diseases) spread through time and
space.
Phases of diffusion:
1. Expansion diffusion: Spread from one place to others while remaining
strong in origin (e.g. COVID-19 in Wuhan to the world).
, 2. Relocation diffusion: Spread via movement of people (e.g. cholera
outbreaks from Haiti to surrounding regions).
3. Contagious diffusion: Spread through direct contact, usually neighbouring
areas first
4. Hierarchical diffusion: Spread through structured order, often urban to rural
(e.g. HIV in cities before villages).
Barriers to diffusion:
o Physical: Mountains, oceans, climate zones.
o Socio-economic: Quarantine, healthcare systems, education, cultural
practices, income, access to treatment.
1.b. There is a relationship between physical factors and the prevalence of disease
which can change over time.
Global patterns of temperature, precipitation, relief and water sources and
how they affect patterns of disease.
Temperature: Affects vector-borne diseases like malaria (20–30°C optimal for
mosquito breeding).
Precipitation: High rainfall leads to stagnant water, breeding grounds for
mosquitoes, waterborne diseases (cholera, dengue).
Relief: High altitudes are typically less hospitable to vectors like mosquitoes.
Water sources: Stagnant or contaminated water increases risk of waterborne
diseases (cholera, typhoid, schistosomiasis).
Physical factors can influence vectors of disease such as the prevalence of
mosquitoes in warm, humid areas close to water sources.
Mosquitoes: Thrive in humid, warm areas with standing water (e.g. puddles,
rice paddies).
Tsetse flies (sleeping sickness): Prefer woodlands and humid savannahs of
sub-Saharan Africa.
Ticks (Lyme disease, Crimean-Congo hemorrhagic fever): Prefer temperate
forested zones with animal hosts.
How seasonal variations influence disease outbreaks such as periods of
drought or monsoon rains.
Droughts: Reduced water access leads to poor hygiene and outbreaks of
diarrhoeal diseases.
Monsoons: Flooding spreads contaminants, ideal for waterborne diseases like
leptospirosis, cholera.
determine these?
1.a. Diseases can be classified and their patterns mapped. The spread of diseases
is complex and influenced by several factors.
How diseases can be classified, including infectious and non-infectious,
communicable and noncommunicable, contagious and non-contagious,
epidemic, endemic and pandemic.
Infectious vs Non-infectious:
o Infectious: Caused by pathogens (bacteria, viruses, fungi, parasites).
Can spread between individuals (e.g. TB, HIV).
o Non-infectious: Not caused by pathogens. Often chronic or lifestyle-
related (e.g. diabetes, heart disease).
Communicable vs Non-communicable:
o Communicable: Can be transmitted directly or indirectly (e.g. malaria,
cholera).
o Non-communicable: Not passed person to person. Often influenced by
genetics, environment, lifestyle (e.g. cancer, asthma).
Contagious vs Non-contagious:
o Contagious: Spread easily via direct contact (e.g. flu, COVID-19).
o Non-contagious: Still infectious but not spread easily (e.g. malaria—
requires vector).
Epidemic: Sudden increase in disease cases above normal in a specific area
(e.g. Ebola outbreak in West Africa).
Endemic: Constant presence of a disease within a region or population (e.g.
malaria in parts of sub-Saharan Africa).
Pandemic: Epidemic that spreads across countries or continents (e.g. COVID-
19, HIV/AIDS globally).
Patterns of diseases, including global distributions of malaria, HIV,
tuberculosis, diabetes and cardio-vascular disease.
Malaria:
o Mostly in tropical and subtropical regions (Sub-Saharan Africa, SE
Asia, parts of South America).
o Transmission relies on presence of Anopheles mosquitoes.
, o Absent in temperate zones due to cooler climate unsuitable for vector
survival.
HIV/AIDS:
o Highest prevalence in Sub-Saharan Africa, especially Southern Africa
(e.g. Eswatini, Botswana).
o Urban areas in all continents affected.
o Transmission through bodily fluids—sexual contact, blood transfusions,
childbirth.
Tuberculosis (TB):
o High incidence in developing regions: South-East Asia, Africa.
o Often linked with HIV co-infection and poverty.
o Resurgence in urban, overcrowded settings and areas with poor
healthcare.
Diabetes:
o Increasing globally, especially in high-income countries and rapidly
urbanising low-income countries.
o Associated with diet, obesity, sedentary lifestyles.
o India and China have highest absolute numbers.
Cardiovascular Disease (CVD):
o Leading cause of death globally.
o High rates in high-income nations due to ageing populations, poor
diets, sedentary lifestyles.
o Growing prevalence in MICs due to lifestyle transitions.
Disease diffusion and spread to new areas (Hägerstrand model), including the
phases of diffusion, physical and socio-economic barriers.
Hägerstrand's diffusion model (geographer Torsten Hägerstrand):
o Focuses on how innovations (or diseases) spread through time and
space.
Phases of diffusion:
1. Expansion diffusion: Spread from one place to others while remaining
strong in origin (e.g. COVID-19 in Wuhan to the world).
, 2. Relocation diffusion: Spread via movement of people (e.g. cholera
outbreaks from Haiti to surrounding regions).
3. Contagious diffusion: Spread through direct contact, usually neighbouring
areas first
4. Hierarchical diffusion: Spread through structured order, often urban to rural
(e.g. HIV in cities before villages).
Barriers to diffusion:
o Physical: Mountains, oceans, climate zones.
o Socio-economic: Quarantine, healthcare systems, education, cultural
practices, income, access to treatment.
1.b. There is a relationship between physical factors and the prevalence of disease
which can change over time.
Global patterns of temperature, precipitation, relief and water sources and
how they affect patterns of disease.
Temperature: Affects vector-borne diseases like malaria (20–30°C optimal for
mosquito breeding).
Precipitation: High rainfall leads to stagnant water, breeding grounds for
mosquitoes, waterborne diseases (cholera, dengue).
Relief: High altitudes are typically less hospitable to vectors like mosquitoes.
Water sources: Stagnant or contaminated water increases risk of waterborne
diseases (cholera, typhoid, schistosomiasis).
Physical factors can influence vectors of disease such as the prevalence of
mosquitoes in warm, humid areas close to water sources.
Mosquitoes: Thrive in humid, warm areas with standing water (e.g. puddles,
rice paddies).
Tsetse flies (sleeping sickness): Prefer woodlands and humid savannahs of
sub-Saharan Africa.
Ticks (Lyme disease, Crimean-Congo hemorrhagic fever): Prefer temperate
forested zones with animal hosts.
How seasonal variations influence disease outbreaks such as periods of
drought or monsoon rains.
Droughts: Reduced water access leads to poor hygiene and outbreaks of
diarrhoeal diseases.
Monsoons: Flooding spreads contaminants, ideal for waterborne diseases like
leptospirosis, cholera.
