DD

• Health

  The combination of physical, mental/emotional, and social well-being
• Epidemiology


  Branch of medical science concerned with the incidence, distribution, and control of diseases that affect large numbers of people.
• infectious disease

  A disease that is caused by a pathogen and that can be spread from one individual to another.
• non-infectious disease

  a disease that cannot spread from one person to another
• contagious


  Able to be passed easily from one person to another directly
• non-contagious disease

  not readily transmitted from one host to another
• communicable disease

  A disease that can be spread from one person or species to another, directly or indirectly
• non-communicable disease


  a disease not capable of being spread from one person to another
• Types of NCDs


  Cardiovascular

  Cancer

  Chronic respiratory

  Diabetes
• endemic disease

  Present at a continuous level throughout a population/geographic area
• epidemic


  A widespread outbreak of an infectious disease.
• Pandemic


  Disease that occurs over a wide geographic area and affects a very high proportion of the population.
• zoonotic disease


  a disease communicable from animals to humans under natural conditions; also know as zoonosis
• mortality


  death
• Morbidity

  Refers to ill health in an individual and the levels of ill health in a population or group.
• Vector


  A third party organism that carries and transmits a communicable disease
• Pathogen


  An organism that causes disease
• prevalence of disease

  total number of existing cases with respect to the entire population
• incidence of disease


  the number of new cases of a disease in a given area or population during a given period of time
• incidence rate


  number of people contracting a disease during a time period, per head of those at risk
• example of endemic disease

  common cold, affects virtually everyone
• example of epidemic


  Ebola, killed 11,000 from 14-16
• Pandemic example


  Covid-19
• 4 Hagerstrand Models of Diffusion

  Expansion

  Relocation

  Contagious

  Hierarchical
• Expansion Diffusion


  One place of origin, spreads but stays in the origin. For example, TB in East Asia, where 22 countries have had 80% of cases.
• relocation diffusion


  Moves from one place to another. Cholera spread Nepal to Haiti, Covid-19 spread from China to Europe most significantly at first.
• Contagious Diffusion

  Spreads by direct contact. Influence strongest at origin, lessens as you go away. Ebola example.
• Hierarchical Diffusion


  Spreads through a group or class, around a city. Channelled through road, rail or air. For example, H1N1 in LA first spread around city .
• Neighbourhood effect


  Probability of contact between a carrier and non carrier is determined by the number of people in a 5x5km square. More people = higher probability.
• 4 stages of diffusion

  Primary step sees the first rise in diffusion rate.

  Expansion step sees acceleration in diffusion rate, which starts to level out in Condensation step, until it is level in Saturation Step.
• Physical barriers to diffusion list

  Neighbourhood effect

  Island or land borders

  Transport links are poor

  Physical geographic barriers (terrain, climate, rivers, water, distance)

  Trade

  Quarantine

  Communication
• Socioeconomic barriers to diffusion

  Poverty/wealth

  Class separation

  Treatments

  Migration

  Social boundaries (personal space)
• How does climate change impact disease (general)?

  Sea level rise pollutes water sources and increases incidence of water borne diseases, devastating poor low lying areas.

  Mass migration could move diseases around, due to climate crisis.

  Tropical countries could see devastating epidemics.

  Food crisis could cause starvation, malnutrition and dehydration.

  $100bn a year of aid would be needed, possibly diverted from healthcare.

  83% rise in food prices could cause malnutrition.

  Temperature rise leads to rise in Lymes Disease, kidney stones, allergies.

  More pollen = more hayfever and sneezing.

  Ecoli increases by 8%.
• West Nile Virus: epidemology, symptoms, history, prevention, link to climate change

  Leading cause of mosquito borne disease in US. No vaccines. 1 in 5 get symptoms, 1 in 150 serious. 1 in 1500 die. Recovery can take weeks or months, or be permanent.

  Symptoms are:

  - encaphilitis

  - meningitis

  - fever, headache, neck stiffness, stupour, disorientation, coma, tremours, convulsions, muscle weakness, vision loss, numbness and paralysis.

  History: first identified Uganda 1937, first US case in 1999 in NYC, now widespread globally. 286 US deaths in 2012. Birds spread virus to other mosquitos.

  Prevention: pesticides and land use changes to deny stagnant water pools.

  Climate change: allows spread of mosquitos further north, into densely populated temperate regions. Could be as far north as British Columbia by 2080. Climate change reduces effectiveness of prevention. Vector mosquito now found in Southern England, no UK cases yet - they live in the increasingly warm salt marshes of the Thames estuary.
• How can extreme weather affect disease?

  Heat and droughts can fuel forest fires that drive disease-spreading wildlife closer to humans.

  Droughts and floods affect crop yield, which causes malnutrition, and increases vulnerability of other disease.

  Flooding provides breeding ground for vector insects, and can cause water contamination, leading to water borne diseases.
• How did climate change impact ebola?

  Dry seasons followed by heavy rain produce an abundance of fruit, leading to increased fruit bat exposure to humans, providing more close contact.

  Pressure on resources will force more people into alternative food sources, including bats. 50% of historical ebola outbreaks have been linked with bushmeat handling.
• How has climate change impacted malaria?

  Longer transmission season due to longer warm and wet periods.

  Larger range due to increased temperatures.

  Plasmodium reproduces faster in warmer temperatures.

  Mosquitos take blood meals more often.

  High rainfall increases reproduction rates.
• Least likely transmission type to be affected by climate change and why?

  Direct transmission - spends little to no time outside the body, so unaffected by environmental factors.
• Impact of climate change on vector borne diseases?

  Temperature changes allows wider vector range. Survival rates are also affected. It impacts the susceptibility of vectors to pathogens. Changes in feeding rate and host contact.

  More precipitation = easier reproduction due to more stagnant water. Alternatively, snow etc can destroy breeding grounds. Low precip can turn previously fresh water into stagnant water. Increased humidity improves vector survival.

  Changes in sea level alter estuary flows and change existing salt marshes.
• Impact of climate change on water borne diseases?

  Flooding can cause contamination of potable water with pathogens.

  Air temperatures can impact reproduction of pathogens in water.

  Changes in the food web due to climate change can influence reproduction and survival of certain water borne diseases (for example, cholera depends on zooplankton, which sees population booms in warm water)