Professor Carter`s slides

DDT and Malaria Control:
Public Health vs.
Eric D. Carter, Ph.D. Geography
Anthropology Department
TEC-154, Spring 2011
Malaria: Global Impact
• Malaria today is in the
top 3 of causes of
mortality by infectious
disease (HIV/AIDS, TB)
• 300-500 million cases of
malaria each year
• 2000 children per day
die of malaria
• Impacts economic
WHO map of malaria transmission risk (2003)
WHO map of estimated incidence of clinical malaria episodes (2004)
Transmission Cycle of Malaria
• Vector-borne disease
• Agent: Plasmodium
– 2 major species: P.
falciparum, P. vivax, etc.
• Vector: Anopheles
– 400 species; 40 are
efficient vectors
Female A. gambiae mosquito taking
blood meal
Malaria: Long-term trends
• Global malaria
incidence declined
dramatically from
1945 to late 1960s.
– WHO global
eradication program
(using DDT)
• Resurgence of
malaria starting in
World Health Organization, 1999
DDT and Malaria Control
• DDT was once the most important weapon in
malaria control.
• Whether DDT should be used remains a
controversial issue.
• The controversy seems to pit
environmentalists (anti-DDT) against some
public health advocates (pro-DDT).
Goals for Today
• To shed some light on the history of DDT's use
in malaria eradication;
• To examine the debate over DDT’s use in
malaria control;
• To draw some historical lessons to provide
guidance for future action.
Where I’m coming from
A brief history of malaria
Malaria Control before DDT
• DDT arrives on the scene around 1945
• What technologies were used in malaria
control before?
– Mainly, methods of “environmental sanitation”
aimed at mosquito breeding areas.
Malaria Control before DDT
Drainage work in
Northwest Argentina
Malaria Control Before DDT
Drainage work in southern U.S. (Tennessee Valley Authority)
Malaria Control before DDT
Application of larvicides
(Paris green – copper aceto
arsenate) in TVA projects
Stream shading (“biological
tunnels”) in Argentina
Malaria Control Before DDT
Manipulation of water levels in
TVA reservoirs
Malaria Control Before DDT
Topographic mapping, frequent
environmental monitoring
Malaria Control Before DDT
• Technologies (e.g. drainage) associated with a
particular social and spatial organization of labor.
– The technologies do not “stand alone”
– New technologies cannot be simply “plugged in” to
existing models and systems
• Focus pre-DDT: unpredictable, disorderly and
dynamic nature (“think like a mosquito”)
• Focus post-DDT: homogenous, stable, predictable
human habitats (i.e. houses)
DDT and Malaria Control
• Why was DDT a
revolutionary technology
for malaria control?
– Simplicity
– Potency
– Residual action
– Safety
– Cost effectiveness
– Transferability
Anti-Malaria Spraying
in Guyana
DDT and Malaria Eradication
• How did the malaria
eradication program work?
– Define a territory
– Spray every house in the area
with DDT twice a year (indoor
residual spraying)
– Break transmission chain by
eliminating mosquitoes
– Treat remaining malaria cases
with pharmaceuticals
– Key: eliminate mosquitoes long
enough to wipe out the
parasite from a human
Malaria Eradication in Argentina
• Backing from the Perón
• Existing public health
infrastructure was good
• Involved other
• Military-style campaign
Malaria Eradication Brigades, 1947
Malaria Eradication in Argentina
• Immediate results
– Between Sept 1947 and
April 1948:
• 170,000 houses sprayed
• 43 tons of pure DDT
• 1 million liters of gasoline
– Malaria incidence dropped
by about 96 percent in that
“One Less Enemy”:
Peronist Propaganda
Global Eradication Campaign
• Success in Argentina, US,
Venezuela, led to Pan
American Health
Organization effort
• Led by Fred L. Soper, an
American epidemiologist,
and Carlos Alvarado, from
• Strategy adopted by WHO
for global malaria
eradication program in 1955
Fred L. Soper
Logic of Malaria Eradication
• Abundant faith in science
and technology
• Reductionist
• Technocratic
– Military logistics
– Benefit-cost analysis
• Modernization theory
Technology transfer
Foreign aid
Cold War context
Cultural change
India Malaria Eradication Campaign Poster, ca. 1960
Global distribution of malaria, 1946-1994
Source: Sachs and Malaney (2002)
Rise and Fall of Eradication
• 1955-1969: WHO Malaria
Eradication program
• Latin America & Caribbean,
• Very effective in some places
– Sri Lanka: 3 million cases (1945)
to 29 (1964)
• Mid-1960s: problems
• Rise of environmentalism
– Rachel Carson’s Silent Spring
• 1969: WHO abandons
eradication strategy
The DDT Debate
The DDT Debate
• Should the use of DDT be banned completely?
• DDT was banned in the US in 1972 and in
many other countries since.
• It was almost banned completely by
international treaty in 2004 (POPs: persistent
organic pollutants)
• A dilemma: DDT may save lives, but it is also
• Highly polemical debate
“The Malaria Clock: A Green Eco-imperialist Legacy of Death”
The Dangers of DDT
• Begins with Rachel
Carson’s book Silent
Spring (1962)
– Sparked the modern
• Compelling case against
DDT and other POPs
Rachel Carson
The Dangers of DDT
• DDT disrupts the
endocrine system and
bioaccumulates up
the food chain
• Impact on birds
– Robins, bald eagles,
peregrine falcons
Rachel Carson
The Dangers of DDT
• Probably carcinogenic
in humans
• Broader critique of
modern technology
disrupting the “balance
of nature”: ecology
becomes political
• Use of DDT and other
pesticides was out of
control by the 1960s
Rachel Carson
Uses of DDT in the 1950s – 1960s
Spraying cattle with DDT, Montana,
Mother spraying DDT, New York, 1945
Corbis photo archives
Corbis photo archives
Advertisement for Penn Salt Chemicals
Time Magazine, June 30, 1947.
critique of DDT
“Another such victory and I
am undone”
Cartoon by Bill Maudlin, 1962
The Dangers of DDT
• Carson was dismayed
by the indiscriminate
use of DDT and other
• Public health
advocates argue that
DDT spraying for
malaria control is
Treat one house for
malaria control in a
Treat one acre of
cotton in a growing
Based on estimates for Guyana; DR Roberts, et al. (1997)
DDT Resistance
• Another argument against DDT
is that insects eventually
develop resistance against it.
• This is true and the
mechanisms are well
understood: natural selection,
selective pressure
• DDT resistance is not the main
reason for the failure of the
global malaria eradication
• And, DDT has proved to be
effective in many places.
16.00 to 100.00
8.00 to 16.00
4.00 to 8.00
2.00 to 4.00
1.00 to 2.00
0.03 to 1.00
Annual Parasite Indexes per 1,000
Source: DR Roberts, et al. (1997)
Malaria Cases vs. Households Sprayed with
Insecticide, Mexico, 1959-1993
Source: Packard, The Making of a Tropical Disease
• DDT use for malaria control is appropriate in
some places and not in others.
– Diverse and uneven geography of risk
– Do we need a universal policy on DDT?
– Assessments of acceptable risk depend on local
• DDT is not a magic bullet. In fact, there is no
magic bullet.
– The technology of DDT was just one ingredient in
malaria eradication
– Where eradication failed, it wasn’t because DDT failed
• Public health infrastructure
• Adequate and sustained levels of funding
• Political support
– Need to de-emphasize technology in discussing
malaria control options
• Politically charged, morality-tale thinking
distracts us from making real achievements in
combating malaria.
– DDT’s symbolic burden
– DDT as a political football