1.a. Classification, patterns, and spread of diseases Flashcards
why do patterns of disease exist between different levels of development?
NCDs in ACs:
- limited transfer of infectious due to vaccinations
- behaviour surrounding diets/alcohol/inactivity=personal
- generally better education and hygiene
Infectious in LIDCs:
- poor living conditions and sanitation => more exposed to pathogens and water-borne diseases
- lack of education/contraception/attitudes towards relationships
Both in EDCs:
-most industrialisation => worst air quality
infectious
= caused by pathogenic micro-organisms (eg. parasites and bacteria)
- diseases spread directly or indirectly from 1 person to another
non-infectious
= not passes from person to person
- long duration and slow progression
- chronic diseases
communicable
= infectious disease transmitted from person to person by direct contact with an infected individual
non-communicable
= disease isn’t capable of spreading from person to person
- 4 main types: diabetes, cancer, chronic respiratory disease, and cardio-vascular
epidemic
= sudden increase of a disease above what is normally expected in that population
- disease attacks many people at the same time and speeds in restricted geographical areas
endemic
= a disease which exists permanently in a geographical area or population group
- e.g. sleeping sickness confined to rural areas in sub-Saharan Africa
pandemic
= an extensive epidemic - more widespread, affecting many countries and continents
- e.g. black plague in mid 14th century, COVID
epidemiology, what does it depend on?
= study that helps to analyse patterns/causes/effects of disease
- depends on DEMOGRAPHICS AND AVAILABILITY OF RESOURCES
neighbourhood effect
= probability of contact between a carrier and non-carrier is determined by the number of people living in each 5*5km grid square and their distance apart = DISTANCE-DECAY FUNCTION + example of EXPANSION diffusion
why does distance-decay become less important overtime?
due to networks evolving and more efficient tech/transport means that the once distance parts of the world move even closer together
facilitating spread
- airports (airborne)
- cargo-ships (more in Acs due to increase amount of trade)
- heavily population areas (e.g. slums and natural disaster camps)
barriers to diffusion PHYSICAL
- climate
- distance/ remoteness= bodies of water/deserts/mountains (often too cold for diseases to survive)
- restriction of in and out migration
barriers to diffusion HUMAN
- international border controls
- sparsely populated areas
- management via mass vaccination programmes/ heightened awareness of improved hygiene/ cancelation of large public events
what model shows the cumulative number of cases as time goes on?
the HAGERSTRAND MODEL
the 4 main stages of the Hagerstrand model?
1) PRIMARY STAGE
- outbreak is slow as starts from a fixed point
2) EXPANSION STAGE
- rapid growth due to contageous diffusion in population (flows of people), rate of infection increase rapidly
3) CONDENSATION STAGE
-spread slows as population becomes immune/already infected/vaccinations and other barriers to diffusion take over
4) SATURATION STAGE
- diffusion/spread stops (most infected)
different curves to Hagerstrand model?
- better policies e.g. wearing face masks or v. programmes
- varies based on size of population and density of population
hierarchical diffusion
= spreads through an ordered sequence of places: large city centres with high connectivity and contact -> isolated and smaller villages
-road/rail/air travel all facilitate network
e.g. 2009 when H1N1 became a pandemic due to International al flights and airports
network diffusion
= diseases spread by transportation and social network
expansion diffusion
- most common and traditional
= disease has a source, carriers in source area remain infected but disease expands into new areas - likely to weaken as expands
e.g. H1N1 flu virus sourced in Mexico
relocation diffusion
= disease leaves origin and moves into a new area
e/g/ cholera epidemic Haiti 2010 originated in Nepal, only relocated due to International aid workers flying over to tackle effects of earthquake
contagious
= class of infectious diseases which are easily spread by direct or indirect contact between people
- strongly influenced by distance
zoonotic
= infectious diseases of animals e.g. rabies and the plague, which can cause a disease when transmitted from animals to humans
patterns of malaria
Infectious disease in Africa, Latin America, SE Asia
- spread my mosquitos that thrive inward and humid conditions => equatorial and mountain ranges or cool/dry areas unaffected
