DDT and Malaria Control: Public Health vs.

Environmentalism?

Eric D. Carter, Ph.D. GeographyAnthropology 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 development

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

parasite– 2 major species: P.

falciparum, P. vivax, etc.

• Vector: Anopheles mosquito– 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 1970s 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 eradication

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 population

Malaria Eradication in Argentina

• Backing from the Perón government

• Existing public health infrastructure was good

• Involved other technologies

• 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 time.

“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 Argentina

• 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, 1946-1994Source: Sachs and Malaney (2002)

Rise and Fall of Eradication• 1955-1969: WHO Malaria

Eradication program• Latin America & Caribbean,

Asia• 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 (1962)

• 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 hazardous.

• Highly polemical debate

“The Malaria Clock: A Green Eco-imperialist Legacy of Death”Junkscience.com

The Dangers of DDT

• Begins with Rachel Carson’s book Silent Spring (1962)– Sparked the modern

environmental movement

• 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

Mother spraying DDT, New York, 1945Corbis photo archives

Spraying cattle with DDT, Montana, 1947Corbis photo archives

Advertisement for Penn Salt ChemicalsTime Magazine, June 30, 1947. Source: http://www.someareboojums.org/blog/

“Another such victory and I am undone”Cartoon by Bill Maudlin, 1962Source: http://www.americaslibrary.gov/assets/aa/carson/aa_carson_consequenc_2_e.jpg

Early environmentalist critique of DDT

The Dangers of DDT

• Carson was dismayed by the indiscriminate use of DDT and other POPs

• Public health advocates argue that DDT spraying for malaria control is different

Treat one house for malaria control in a

year

Treat one acre of cotton in a growing

season

kilograms

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 program

• And, DDT has proved to be effective in many places.

0.03 to 1.001.00 to 2.002.00 to 4.004.00 to 8.008.00 to 16.0016.00 to 100.00

Annual Parasite Indexes per 1,000Source: DR Roberts, et al. (1997)

Malaria Cases vs. Households Sprayed with Insecticide, Mexico, 1959-1993Source: Packard, The Making of a Tropical Disease

Conclusions

Conclusions

• 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

circumstances

Conclusions

• 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

Conclusions

• Politically charged, morality-tale thinking distracts us from making real achievements in combating malaria.– DDT’s symbolic burden– DDT as a political football