Download Unit 4 - The Spread of Disease

THE SPREAD OF DISEASE
IB GEOGRAPHY II
OBJECTIVE
• By the end of this lesson, students will be able to:
• Explain how the geographic concepts of diffusion
by relocation and by expansion apply to the spread
of diseases.
• Examine the application of the concept of barriers
in attempts to limit the spread of diseases.
• Describe the factors that have enabled reduction in
incidence of a disease.
POSSIBLE EXAM QUESTIONS
• Explain how the geographic concept of
diffusion by ___________ applies to the
spread of diseases with reference to one
disease.
• Insert any diffusion type in blank space.
OPENING ACTIVITY: VIDEO ANALYSIS
• Catch it, Bin it, Kill It:
http://www.youtube.com/watch?v=TcauOxevK0g&feature=pl
ayer_embedded
• Coughs & Sneezes 1945:
http://www.youtube.com/watch?v=tomNghONyNM&feature
=player_embedded
BACKGROUND ON THE SPREAD OF
DISEASE
• Infectious diseases do not stay put. They
tend to move and spread.
• Diseases are more mobile than
previously, because we are more mobile
than before, and we carry diseases with
us.
PANDEMIC RISK INDEX
• A pandemic is a disease which has spread to affect
a very large area, either several continents or
possibly most of the globe.
• The Pandemic Risk Index takes the following into
account:
– The risk of a particular disease emerging in a country
– The risk of disease spreading to and within one country
– The capacity of a country to contain the disease
DISEASE DIFFUSION
• Refers to the spread of a disease into new locations
FRICTIONAL EFFECT OF DISTANCE
(DISTANCE DECAY)
• Suggests that areas that
are closer to the source (of
disease) are more likely to
be affected by it, whereas
areas further away from
the source are less likely to
be affected and/or will be
affected at a later date.
BARRIERS TO DIFFUSION
• Some physical features act as a barrier towards
diffusion, including:
• Mountains
• Bodies of water
• Political and Economic boundaries may also limit the
spread of disease.
• Travel restrictions and screening of travelers can
form ‘human’ barriers.
• Public health advice can also help in some cases.
TYPES OF DIFFUSION
• Expansion diffusion
• Relocation diffusion
• Contagious diffusion
• Hierarchal diffusion
• Network diffusion
• Mixed Diffusion
• Note: a Disease can spread with a combination of above types
EXPANSION DIFFUSION
• Occurs when the
expanding disease
has a source and
diffuses outwards
into new areas
EXAMPLE OF EXPANSION DIFFUSION
• 1918 Spanish Flu
killed an estimated
40 million people
worldwide within
just a few months
RELOCATION DIFFUSION
• Occurs when the spreading disease
moves into new areas, leaving behind its
origin or source of the disease.
EXAMPLE OF RELOCATION DIFFUSION
• for example a person infected with HIV
moving into a new location.
CONTAGIOUS DIFFUSION
• The spread of
an infectious
disease
through the
direct contact
of individuals
with those
infected.
EXAMPLE OF CONTAGIOUS DIFFUSION
• The common cold:
• Maria gets a cold. In the next few days
those who sit near her in class get the
same cold from her sneezing near them
or touching desks, etc. Those people
can then get the same cold and pass it
to people sitting near them.
HIERARCHAL DIFFUSION
• Occurs when a
phenomenon spreads
through an ordered
sequence of classes or
places, for example from
cities to large urban
areas to small urban
areas.
EXAMPLE OF HIERARCHAL DIFFUSION
• The H1N1 Virus and other diseases.
• H1N1 started in Mexico City, but first saw
prevalence in other large cities (LA, NYC,
Chicago) before seeing a presence in smaller
cities or rural towns.
NETWORK DIFFUSION
• Occurs when a
disease spreads via
transportation
networks.
• the spread of HIV in
southern Africa along
transport routes.
ANOTHER EXAMPLE OF NETWORK DIFFUSION
• There are some cases of malaria in the
US every year for example, and most of
those are close to airports. Mosquitoes
survive in the plane just long enough to
bite someone when they leave.
MIXED DIFFUSION
• Usually a combination
of contagious
diffusion and
hierarchal diffusion
• Or a combination of at
least 2 other diffusion
types
SWINE FLU ACTIVITY
SWINE FLU
• Also known as 2009 H1N1 type A influenza, is a
human disease.
• The disease originally was nicknamed swine flu
because the virus that causes the disease originally
jumped to humans from the live pigs in which it
evolved.
• The 2009 "swine flu" outbreak was different. It was
caused by a new swine flu virus that has changed in
ways that allow it to spread from person to person -among people who haven't had any contact with
pigs.
H1N1 (SWINE FLU)
• Researchers accurately plotted swine flu’s
course around the world by tracking air
travel.
• Between March and April 2009, more than
2 million people flew from Mexico to more
than 1000 cities in 164 countries.
• 4/5 of the people to cities in the US.
• http://thelede.blogs.nytimes.com/2009/07/29/a-newairport-ritual-swine-flu-screening/ (2 videos)
STUDY THE 4 MAPS ON HANDOUT
• Describe the diffusion of the H1N1 (swine flu)
virus in 2009.
• Name the type(s) of disease diffusion indicated
by the maps. What evidence proves it?
• What are reasons for the pattern you see?
REDUCTION IN INCIDENCE OF DISEASES
• Public health campaigns have been used for
various diseases over the years.
• There have been a range of recent scares over
possible pandemics.
• In recent years, there have been hysterical
headlines warning of mass deaths from
various diseases.
HEALTH SCREENINGS AT AIRPORTS
• In 2009, a new
outbreak of Avian Flu
was reported in China.
• At airports, they
screen passengers by
taking their
temperature before
allowing them on the
plane.
TRENDS IN PUBLIC HEALTH CAMPAIGNS
• Watch this slideshow from BBC to see how
countries have tried to reduce the incidence
of disease.
• How have the messages seen changed over
time? How have they remained the same?
• How does gender play a role in reaching the
target audience in many of these ads?
http://www.bbc.co.uk/news/health-10913218 (4 minutes)