Transcript Introduction to the Geography of Health

An Introduction to the Geography of Health
Chapter 11: Integrating Approaches
to the Study of the Geography of Health
Photo by Heike Alberts
Although ecological, social, and spatial approaches offer
important and unique perspectives to particular health
problems, a combination of approaches is ultimately the
optimal way to explore many critical questions.
How could a combination of these approaches be used in
investigating the following issues:
a) deciding the location of a new hospital?
b) developing a vector-control program for Chagas disease?
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Global Infectious Disease Campaigns
Programs to control or eradicate infectious diseases often
benefit from a combination of approaches.
For the remainder of this PowerPoint we will discuss ways
in which combining different geographic approaches to
health could inform infectious disease campaigns.
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Policymakers recognize three distinct approaches to
tackling infectious disease:
disease control: restricting the circulation of a
disease to background levels
disease elimination: the removal of a disease from
a particular area
disease eradication: the complete removal of a
disease from existence
What kinds of actions or policy can be
implemented to achieve the elimination
or eradication of a disease?
What are some of the pros and cons of eradication
as opposed to elimination or control?
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What makes eradication feasible?
In theory, all infectious diseases should be eradicable
given the right tools (Dowdle 1998); in practice, there
are distinct technical, biological, and social factors that
make some diseases easier targets than others.
What factors might influence how
easy it is to eradicate a disease?
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A) Eradication must be biologically and
technically possible
Biological and technical feasibility hinge upon
ecological factors such as:
1) the availability of a suitable intervention to
interrupt transmission of the disease,
2) humans being central to the life cycle with no
other vertebrate or environmental reservoirs,
3) visible symptoms or clear diagnostic tests for
identifying individuals with the disease.
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A) Eradication must be biologically and
technically possible
B) Social conditions, particularly economic
and political factors, must favor eradication
“…of all the lessons learned in the past 85 years, none is more
important than the recognition that societal and political
considerations ultimately determine the success of a disease
eradication effort” Aylward et al. (2000: 1515).
What sorts of social factors might we take into
consideration in eradication campaigns?
Which diseases would you suggest might be
eradicable, given these criteria?
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Top Candidates for Disease Eradication
Rank
Disease
Est. Cases
(Date)
Transmission
Breaking Cycle
1
Polio (virus)
1936 (2005)
Sewagecontaminated
water
Oral vaccine (drops)
2
Guinea Worm
(worm)
12,000 (2005)
Infected
drinking water
Filter or treat pond
water; dig wells
deeper to avoid
contamination
3
Lymphatic
120 million
Filariasis (worm) (1996)
Mosquitoes
De-worming pills;
patients must be
treated annually for 6
years
4
Measles (virus)
Airborne
droplet
Vaccine (injection)
30 million
annually
Source: New York Times (2006)
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Top Candidates for Disease Eradication
Rank
Disease
Est. Cases
(Date)
Transmission
Breaking Cycle
5
Blinding
Trachoma
(bacteria)
84 million
affected; 2
million blind
Spread by flies
Antibiotics; access to
clean water; covered
latrines; surgery in late
stages
6
Onchocerciasis
(river blindness)
(worm)
18 million
affected;
500,000 blind
Spread by bite
of black flies
Insecticides for flies;
de-worming pills for
patients
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Hepatitis B
(virus)
350 million
carriers
By blood or
body fluids
Three vaccine doses
8
Leprosy
(bacteria)
2.8 million
affected; 1-2
million
disabled
Transmission by Antibiotic triple
extended
therapy daily for a year
physical contact
Source: New York Times (2006)
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Top Candidates for Disease Eradication
Rank
Disease
Est. Cases
(Date)
Transmission
9
Neonatal
Tetanus
(bacteria)
200,000 deaths Umbilical cord
per year; 95% cut with dirty
death rate
blade
10
Iodine
Deficiency
740 million
Breaking Cycle
Clean delivery
practices; vaccine for
mother and baby
Goiters in
Iodized salt
adults; brain
damage in fetus
Source: New York Times (2006)
What commonalities can you identify
among these diseases?
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“Orphan Diseases” and
“Neglected Tropical Diseases”
Ultimately, which diseases get attention is often more of a
political or economic decision than a medical one.
The term “orphan disease” is used to refer to diseases that
have been neglected because so few people suffer from them,
or the populations that suffer from them are so poor that
there is little economic incentive to develop therapies.
Many of these neglected diseases are found in the tropics,
owing to the poverty of populations in many tropical
regions—hence the term “neglected tropical diseases.”
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Global Infectious Disease Campaigns
Past and ongoing disease
eradication campaigns
Dahlem Workshop criteria for feasibility of
eradication
Success?
Disease
Dates
Biological
feasibility
Cost–benefit
positive
Broad support?
Yellow fever
1915–1977
No
No
No
No
Yaws
1954–1967
No
No
No
No
Malaria
1955–1969
No
Yes
Yes
No
Smallpox
1958–1979
Yes
Yes
Yes
Yes
Dracunculiasis
1980–?
Yes
Yes
Variable
ongoing
Polio
1988 –?
Yes
Yes
Variable
ongoing
Source: Adapted from Aylward et al. (2000)
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Smallpox Eradication
The eradication of smallpox remains
a high point in global public health.
In 1979, two years after the last
known naturally-transmitted case,
the WHO declared the disease
officially eradicated; by 1986,
routine vaccination had ceased in all
countries (WHO 2010).
Source: WHO (2010a)
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Source: CDC (1980)
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The smallpox eradication campaign from
1967 to 1979 probably cost US$200-300
million, but may have resulted in annual
savings of $2,500 million (Wickett 2002: 69).
Another estimate suggests that the
economic benefit of eradicating smallpox
may be as high as US$450 saved for every
dollar spent (Barrett 2004: 684).
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Sadly, over the past 30 years, humankind has not managed to
repeat this success with any other human disease.
The ecology of smallpox and the social setting in which it was
tackled made it a relatively “easy” target for eradication,
calling into question whether we can repeat this success with
any other disease.
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Written descriptions of smallpox
date as far back as 400 AD (CDC
2004). The disease may have
emerged from an animal poxvirus as
early as 10,000 BC (Wickett 2002).
The disease is primarily spread by
airborne transmission, but can also
be spread via fomites such as
infected bedding, although with
much lower transmissibility.
Source: Sahagún, B., circa 1585
This illustration from the sixteenth
century shows a smallpox victim.
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Smallpox had about a 30%
mortality rate, led to
blindness, and left many
of those infected
permanently disfigured.
A smallpox sufferer in Dekina, Nigeria, 1969
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Source: CDC and Conrad (1969)
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When the WHO’s global
eradication program was
launched in 1967 there
was still no effective
treatment for smallpox.
Source: CDC (1975)
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An effective vaccination was
available, however, developed from
a long history of experimentation
with smallpox inoculation.
What characteristics of
smallpox made it a relatively
“easy” target for eradication?
Source: CDC, Millar (1969)
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A variety of factors related to the ecology of
smallpox made it a good target for eradication.
+ No animal reservoir or vector
+ Distinctive symptoms made it easy to
recognize
+ People are only at risk when in the
presence of an infected person with
obvious symptoms
+ Vaccination is very effective
+ Vaccination is easy to administer and
lasts about ten years
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The smallpox campaign’s primary goal was mass vaccination
of at least 80% of every afflicted population in order to
ensure that herd immunity protected the remainder.
Owing to the remoteness of much of the afflicted population,
it soon became clear that this goal was unrealistic.
A poster promoting smallpox
and measles vaccination.
Source: CDC (date unknown)
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Fortunately, an
understanding of the
disease’s diffusion patterns
suggested another
strategy: ring vaccination.
The “x”s represent infected people and the
“o”s represent the people around them. A
dotted line between two individuals
indicates contact between them.
Each circle on the diagram encompasses the
individuals who would be vaccinated in a
ring vaccination campaign: this comprises
the infected person, the infected person’s
contacts, and contacts of those contacts.
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The world’s last naturally-acquired case of smallpox
was recorded in Somalia in October 1977.
Today, the virus remains only in several highsecurity facilities, and some countries continue to
keep stockpiles of the vaccine.
What are some of the arguments
for and against keeping stockpiles
of smallpox vaccine?
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Polio Eradication
Poliomyelitis (polio) is currently the primary global
target for eradication. Policymakers had hoped that the
disease would be eradicated by the year 2000, but
isolated pockets persist.
Many ecological and social aspects of the disease make
it a more difficult target for eradication than smallpox.
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Polio is a viral disease that is highly
infectious. Symptoms include
fever, fatigue, headache and
vomiting, making it difficult for a
layperson to differentiate mild
cases from a host of other
diseases by symptoms alone.
Infection leads to irreversible paralysis in
approximately one in 200 cases; among those
paralyzed, 5–10% die when breathing muscles
become immobilized.
Those who survive may require considerable
therapy to regain physical function.
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Source: CDC and Farmer (1963)
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The virus is primarily spread via the
fecal–oral route of transmission
and is commonly contracted from
contaminated water supplies.
The virus is also found at low
concentrations in oral secretions
and can be passed directly among
individuals through contact with
saliva or airborne droplets.
Source: CDC and Hilpertshauser (1963)
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Although there is no cure for polio, two
effective vaccines were developed in the
1950s: an injectable inactivated vaccine
and a live oral polio vaccine (OPV).
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The potential to control polio
with these vaccines was
quickly realized at a national
level and elimination
campaigns were initiated in
several countries.
This image shows an infant being
vaccinated against polio in Somalia,
which has had recent success in
eliminating polio.
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Source: WHO (2010d)
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The Global Polio Eradication
Initiative was launched in
1988, led by the WHO, Rotary
International, the US CDC,
and UNICEF.
Source: WHO (2010d)
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The eradication campaign focused
on four approaches:
• high infant immunization
coverage,
• surveillance for wild poliovirus,
• laboratory investigation of
paralysis cases in children,
• targeted “mop-up” campaigns.
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Despite great success, the
campaign began to falter between
2003 and 2005 as place-specific
challenges became apparent in
remaining pockets of transmission.
For instance, in Pakistan and
Afghanistan the remoteness of
many populations, conflict, and
cultural resistance to vaccination
led to polio outbreaks.
What characteristics of polio make it a
challenging target for eradication?
Source: CDC, NIP, and Rice, B. (date unknown)
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A variety of factors have made polio eradication a
challenging goal:
• the virus can persist asymptomatically in humans
and in the environment,
• the length of the campaign has led to the waning
of political and donor interest,
• war and instability have thwarted efforts in some
regions,
• significant social resistance has developed to
polio vaccination in some contexts.
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Source: WHO (2010b)
In 2010, there were a total of 908 cases of polio worldwide, most of which
in Tajikistan, Pakistan, and the Democratic Republic of Congo.
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Conclusion
Global campaigns to control disease provide an excellent illustration
of ways in which geographic knowledge can be applied to health
problems. Eradication efforts undoubtedly depend on a rich
understanding of the ecological, social, and spatial facets of diseases.
A combination of ecological, social, and spatial approaches can
similarly provide valuable insights for tackling other health problems.
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Discussion Questions
1.
2.
3.
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Compare the significance of ecological, social, and spatial factors in the
relative success of two of the following eradication campaigns: malaria,
smallpox, dracunculiasis, and polio. How can geographical approaches
to health elucidate the challenges of these campaigns?
Considering the ecological, spatial, and social aspects of polio and
dracunculiasis, which do you consider to have a greater likelihood of
eradication? Taking into account both social and ecological factors,
discuss whether you would support control, elimination, or eradication
of another disease you know about.
To what degree should the rights of the individual be protected in
eradication campaigns? In particular, should individuals have the right
to decline vaccination for themselves or their children?
Why or why not?
Anthamatten and Hazen
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Chapter 11
Discussion Questions
4.
5.
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Discuss the advantages and disadvantages of ecological, social, and
spatial approaches to health. When might each be useful or show its
limitations? What are the pros and cons of a biomedical approach to
health?
How would you describe the sub-discipline of health geography to a
layperson?
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Chapter 11
References
Aylward, R. B. (2006) ‘Eradicating polio: today's challenges and tomorrow's legacy’, Annals of Tropical Medicine and
Parasitology, 100: 401–13.
Barrett, R., Kuzawa, C. W., McDade, T. and Armelagos, G. J. (1998) ‘Emerging and re-emerging infectious diseases: the
third epidemiologic transition’, Annual Review of Anthropology, 27: 247–71.
[CDC] Centers for Disease Control and Conrad, L. (1969) “Image ID# 7170” Public Health Image Library [Online]. Available:
< http://phil.cdc.gov/phil/download.asp> (Accessed 12 Jan 2010).
CDC and Farmer, C. (1963) “Image ID# 2612” Public Health Image Library [Online]. Available: <
http://phil.cdc.gov/phil/download.asp> (Accessed 01 Dec 2010).
CDC and Hilpertshauser, M. (1963) “Image ID# 7224” Public Health Image Library [Online]. Available: <
http://phil.cdc.gov/phil/download.asp> (Accessed 01 Dec 2010).
CDC and Millar, J. (1969) “Image ID# 1985” Public Health Image Library [Online]. Available: <
http://phil.cdc.gov/phil/download.asp> (Accessed 05 Jan 2011).
CDC, NIP, and Rice, B. (date unknown) “Image ID# 134” Public Health Image Library [Online]. Available: <
http://phil.cdc.gov/phil/download.asp> (Accessed 05 Jan 2011).
CDC. (date unknown) “Image ID# 2564” Public Health Image Library [Online]. Available: <
http://phil.cdc.gov/phil/download.asp> (Accessed 12 Jan 2011).
CDC. (1975) “Image ID# 12291” Public Health Image Library [Online]. Available: < http://phil.cdc.gov/phil/download.asp>
(Accessed 05 Jan 2011).
CDC. (1980) “Image ID# 7079” Public Health Image Library [Online]. Available: < http://phil.cdc.gov/phil/download.asp>
(Accessed 30 Nov 2010).
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References
CDC. (2004). “Smallpox Disease Overview” Emergency Preparedness and Response [Online]. Available: <
http://www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp>
Dowdle, W. R. (1998) ‘The principles of disease elimination and eradication’, Bulletin of the World Health Organization, 76
Suppl 2: 22–5.
New York Times. (2006) (20 March 2006) Diseases on the Brink [Online]. Available:
<http://www.nytimes.com/ref/health/2006_BRINK_SERIES.html>.
Sahagún. B. Florentine Codex.
Wickett, J. (2002) ‘The final inch: the eradication of smallpox and beyond’, Social Scientist, 30: 62–78.
WHO. (2010a) Archives of the Smallpox Eradication Programme [Online]. Available:
<http://www.who.int/archives/fonds_collections/bytitle/fonds_6/en/index.html> [Accessed May 07, 2010].
WHO. (2010b) Polio This Week – As of 5 January 2011 [Online]. Available:
<http://www.polioeradication.org/Dataandmonitoring/Poliothisweek.aspx > (Accessed 06 Jan 2011).
WHO. (2010c) Smallpox [Online]. Available: <http://www.who.int/mediacentre/factsheets/smallpox/en/> (Accessed 16
March 2010).
WHO. (2010d). Somalia: Three Years Polio-Free. [Online] Available:
<http://www.who.int/features/galleries/somalia_photo_gallery/en/index.html> (Accessed 06 Jan 2011).
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