Diffusion & Disease

1. Diffusion & Disease

2. What is Diffusion? • : The process by which a characteristic spreads from one place to another over time (people, products, ideas) • Examples: • Architectural styles • Fashion • Language • Technology • Diseases

3. The Spread of Agriculture

4. Ancient Technology The spread of iron technology The spread of the chariot

5. The Diffusion of People

6. Where does diffusion begin? Hearth: the point of origin or place of innovation Diffusion of Buddhism outward from India

7. Who is involved with diffusion? * Innovators – risk-takers, educated, have the resources & desire to try new things * Early adopters - social leaders, popular, educated, usually the first one in the group to have the latest gadget * Early majority - deliberate, they like seeing how new technology will fit in their lives * Late majority - skeptical, traditional, lower socio-economic, they react to peer pressure or economic necessity * Laggards – more traditional, fear of debt, may not have the resources to try new things

9. What are barriers to diffusion? • Time and Distance Decay • The farther from the source and the more time it takes, the less likely innovation is adopted • Cultural Barriers • some ideas are not acceptable in a particular culture e.g. pork, alcohol, contraceptives

10. Different kinds of diffusion

11. 1) Relocation Diffusion • : Ideas and things are spread by the physical movement of people from one place to another • Ex: Amish culture originated in Western Europe, moved to Pennsylvania, is moving westward Amish settlements

12. 2) Expansion Diffusion • The idea originates in a central place and then expands outwards in all directions • So the idea moves, not necessarily the people • The idea stays strong at the hearth • There are 3 subtypes • A. Hierarchical • B. Stimulus • C. Contagious

13. Hierarchical Diffusion • The spread of an idea or thing from a person of authority/high ranking to other people and places • Ex: the spread of fashion trends start with the upper class, and then spread through society Celebrity trendsetters: Cara Delevinge’s eyebrows, Kylie Kardashian’s lips, Kim Kardashian’s makeup contouring

14. Stimulus Diffusion • An idea is spread but it is modified so there will be local variations • Ex: McDonalds has spread to India, but they have modified it to fit the local culture. Hindu people do not eat beef, so they have expanded their vegetarian options

15. Contagious Diffusion • Rapid, widespread diffusion of a characteristic through a population • Spreads through society equally • Ex: ideas on the Internet spread like this; very quickly since everyone has access to them immediately

16. Pandemics and Infectious Diseases

17. Try to guess…what are the top 10 causes of death worldwide 10. Hypertension (2% of all deaths) 9. Vehicular Accidents (2.2% of all deaths) 8. Diabetes (2.7% of all deaths) 7. Diarrhea (2.7% of all deaths) 6. HIV & AIDS (2.7% of all deaths) 5. Lung, Tracheal, & Bronchial Cancers (2.9% of all deaths) 4. Lower Respiratory Infections (5.5% of all deaths) includes pneumonia, tuberculosis, influenza, bronchitis, etc 3. COPD – Chronic Obstructive Pulmonary Disease (5.6% of all deaths) 2. Stroke (11.9% of all deaths) 1. Coronary Heart Disease (13.2% of all deaths)

18. Causes of death in the developed world • Many of the same causes, Heart Disease is still #1 • But there’s no Diarrhea in the Top 10, or HIV/AIDS, • There is Suicide, Alzheimers, Kidney Disease

19. What is “Medical Geography”? • Study of the interconnections between population, health and the environment • Cause and diffusion of disease • Provision and consumption of health care • Social construction of health • Effects of environmental change

20. Some Terms To Know • If a disease is epidemic, ….. there are numerous outbreaks and the situation gets more serious. • If a disease is pandemic, ….. this is a serious situation and it means that it has spread globally.

21. Bacterial, parasitic, or viral? • Bacterial: a disease caused by bacteria, it is alive and so can be killed by antibiotics • Viral: a disease caused by a virus, its symptoms can be alleviated but it can’t be cured, it is not “alive” so can’t be killed; some can be treated with antiviral drugs, which fight infection by inhibiting a virus’s ability to reproduce • Parasitic: a disease caused by a parasite (tiny bug or worm)

22. Cause and Spread of Disease • In 1854 London, England there was a Cholera outbreak where 616 people died • At the time they thought it might be spread by inhaling infected air or eating contaminated food

23. Dr. John Snow (yes, really) used a dot map to map the addresses of cholera victims and the location of water pumps they used • Discovered that most of the cholera victims lived around one pump that was contaminated • Most famous and earliest case of geography and maps being utilized to understand the spread of a disease • https://www.youtube.com/watch?v=1jlsyucUwpo

24. Disease Mapping

25. Where is Cholera today? Why do we not have cholera in Canada/USA anymore?

26. Cholera Deaths • Cholera deaths result from severe dehydration caused by diarrhea • This is treatable; in 2004 only 2.5% of cholera cases were fatal

27. Epidemiology • : the branch of medicine that deals with the incidence, distribution, and control of disease

28. Epidemiologic Transition Theory • Each stage of the demographic transition model has distinctive causes of death • The leading causes of death change from infectious to degenerative types as the demographic transition occurs.

30. Epidemiologic Transition Stage 1 Death because of: • Infectious and parasitic diseases (Black Death) • Malnutrition • High birth rate • High death rate • Slow population growth • Happens in very poor, isolated places • Typical life expectancy: 35

31. Plague • This disease has changed the course of human history • Caused by a bacteria transmitted to humans by fleas from infected rats • There are several types but the most famous is the Bubonic Plague • Named after the hard swollen “buboes” or lumps that develop near the flea bite

32. More Plague • Bubonic plague killed 60%, but some other forms of Plague killed 90% of its victims • When the rats start dying off, the fleas find human hosts • The first incident of this kind of plague was in the years 541-544 when it spread from Egypt to Europe and killed ¼ of Mediterranean Europe and helped in the downfall of the Roman Empire

33. Plague as Biological Weapon • During various Medieval wars, armies would use plague-infected bodies as biological weapons • They would use them to contaminate enemy’s water supply • Or they would catapult the bodies into the cities during a siege • During WW2 the Japanese used it on Chinese soldiers

34. Plague still exists • Today there are antibiotics and a vaccine but there are still pockets where it survives

35. River Blindness • Onchocerciasis (River Blindness): a disease caused by infection with the parasitic worm • It is the second most common cause of blindness due to infection • 17-25 million people are infected • Most infections occur in sub-Saharan Africa, although cases have also been reported in Yemen and isolated areas of Central and South America.

36. Epidemiologic Transition Stage 2 • Death caused by receding pandemics – cholera, tuberculosis, typhus, yellow fever • High birth rate • Death rate starts to drop due to advancements in healthcare and sanitation • Rapid population growth; crowded, dirty cities • Late 19th century Europe and America; or current south Asia, or Latin America • Typical life expectancy: 50

37. 1918 Influenza outbreak • It infected 500 million people • It killed 50 - 100 million of them—3-5% of the world's population • One of the deadliest natural disasters in human history • Most flu outbreaks kill young, elderly, or already weakened patients • In contrast this flu killed mostly healthy young adults

38. How Did It Spread • Modern transportation made it easier for soldiers, sailors, and travelers to spread the disease. • In the USA, the disease was first observed in January 1918 • It struck every corner of the globe • In Canada 50,000 died • http://www.youtube.com/watch?v=rbYwNOcKqqc

39. Epidemiologic Transition Stage 3 • Death caused by degenerative diseases and man-made diseases • Decrease in deaths from infectious diseases (vaccines) • Due to increased tobacco and alcohol use and subsequently fat & caloric intake, deaths due to chronic conditions overtake infectious diseases • Death rates still dropping; people are living longer • Birth rates also now start to drop • Rapid growth (still) • Happens in places like Brazil, Middle East • Typical life expectancy: 60

40. Anti-Vax leads to Measles Outbreaks • Measles was considered eliminated from the USA in 2000 • But now with the anti-vaccination movement, it’s come back • It’s extremely contagious, airborne, and can be deadly • Preventable through immunization

41. Epidemiologic Transition Stage 4 • Death caused by delayed degenerative diseases • Cancer and heart disease • Tobacco, alcohol, poor diet, lack of exercise • Treatment prolongs survival • Increase in aging-related conditions such as Alzheimer's • Birth rate and death rates stabilize • Slow population growth • Happens in richer countries • Typical life expectancy: 70

42. Obesity

43. Epidemiological Transition Stage 5 • Death caused by new diseases, and same reasons as Stage 4 • Some infectious diseases have evolved and returned • New diseases have emerged • New strains of viruses & bacteria are drug resistant • Most people can’t afford new drugs • Populations may be shrinking from low birth rates

44. Malaria • Nearly eradicated in 1950s by spraying DDT in areas infested with the mosquito that carried the parasite. • Returned after 1963 with the evolution of DDT-resistant mosquitos

45. Smallpox • An infectious viral disease • Originally known as the "pox” or "red plague” • It killed millions in the 18th-20th centuries • It killed 20-60% of victims (80% of infected children) • After a vaccine was developed, the disease was eradicated in 1979

46. Polio • An infectious viral disease • Often causes paralysis of the legs • One of the most dreaded childhood diseases of the 20th century • A vaccine was developed in the 1950s • There have been recent outbreaks in Syria and Democratic Republic of Congo

48. HIV/ AIDS • Infection rates are as high as 25% in southern and eastern Africa. • About 35 million people have died of HIV • 36.7 million people were living with HIV in 2016

49. Ebola • Ebola hemorrhagic fever (EHF): a viral hemorrhagic fever • The largest outbreak to date was the epidemic in West Africa in 2013-2016 with 11,310 deaths • It was declared no longer an emergency in March 2016 • The disease kills between 25 -90% of those infected • The virus spreads through bodily fluids

50. New Pandemics • SARS (severe acute respiratory syndrome): a viral respiratory disease • In 2002-2003, an outbreak of SARS in southern China caused an eventual 774 deaths in 37 countries. • No cases of SARS have been reported worldwide since 2004. • H1N1(swine flu): a subtype of the influenza virus • In June 2009, the World Health Organization declared the new strain of swine-origin H1N1 as a pandemic. • This novel virus spread worldwide and had caused about 17,000 deaths by the start of 2010. In August, the World Health Organization declared the H1N1 influenza pandemic over