Eradication Efforts: Malaria vs. Smallpox

In testimony before Congress in 1969, Surgeon General William Stewart famously said that it was time for the United States "to close the book on infectious disease." At the time of his statement, antibiotics and vaccines had left the medical community with a string of impressive victories, from the discovery of penicillin to the near eradication of smallpox and polio. The war, they thought, was almost over.           

Today, confronted with what have become known as emerging and re-emerging infectious diseases, we know better.  While the prevalence of malaria and tuberculosis infections has declined in the developed world, incidences have been increasing in already endemic regions.  In fact, forty-one % of the world's population now lives in areas where malaria is transmitted.(1)  In 2002, malaria was the fourth cause of death in children in developing countries after perinatal conditions, lower respiratory infections, and diarrheal diseases. These alarming figures continue despite over a century of malaria control efforts and the current unprecedented amount of funds allocated toward such efforts.  The large global burden of malaria in the present day gives us cause to stop and ponder what exactly went wrong and why so many infectious diseases still persists in spite of so much attention.

This article examines eradication efforts in the history of global health, focusing on malaria and smallpox.  A comparison of public health efforts targeted at the eradication of these two diseases reveals the importance of social factors, local involvement, and political will.

History of Malaria Control

Perhaps the most aggressive effort against malaria was the Global Malaria Eradication Program.  This program was launched by the World Health Organization in 1955 and depended on two novel tools: the drug chloroquine for treatment of infected individuals and the chemical DDT for mosquito control.(2) 

Armed with the knowledge of these formidable tools, malaria eradication efforts began with a focus on spraying houses with residual insecticides and the prescription of anti-malarial drugs for treatment.(3)  Initial successes included eradication in nations with temperate climates and seasonal malaria transmission. Some countries like India and Sri Lanka had dramatic reductions in the number of malaria outbreaks, later followed by increases to previous levels after efforts ceased. According to the World Health Organization, “other nations had negligible progress (such as Indonesia, Afghanistan, Haiti, and Nicaragua), and some nations were excluded completely from the eradication campaign (most of sub-Saharan Africa)”.(4) 
Yet the emergence of drug resistance in humans, widespread mosquito resistance to insecticides, massive population movements, and lack of community participation made long-term maintenance of the effort untenable. Moreover, the integration of ‘vertical’ anti-malarial programs—programs which relied upon a single, widespread tool —into ‘horizontal’ health services was generally performed without a careful consideration of the best means of achieving both optimum integration and malaria control. Consequently, the gains that had been achieved were lost in many areas, and in 1977, the goal of eradication was officially abandoned to one of control. (5)    

Later on, following the principles of primary health care outlined at the Alma Ata Conference in 1978, many countries proceeded to review their anti-malarial activities “based on the priorities at community level, and within an integrated health care system that makes optimal use of existing resources”.(6)  The basic principle was to adapt planned malaria control efforts to local conditions, taking into account the geographical variation in epidemiological and socioeconomic conditions. While the provision of early diagnosis and effective treatment was regarded as a basic right for all populations at risk, there was an increasing realization that different strategies to control malaria were needed for different malaria situations.                        

As seen through a glance at history, past efforts at eradication were able to reduce malaria in a few places, yet have been largely regarded as failures. While the emergence of resistance to DDT and anti-malarial drugs contributed to such failures, most endemic countries failed to eradicate the disease for a variety of reasons, most of which were not related to the lack of suitable tools. Two of the most common reasons were the prescription of a ‘one size- fits-all’ approach which did not take into account variation in the social and epidemiological characteristics of each targeted community, and the reality that poor health systems were incapable of effectively implementing novel tools and providing adequate surveillance.(7)

Smallpox Eradication

In stark contrast to turbulent history of malaria eradication efforts, smallpox was the first disease to be eradicated, due to the success of the Smallpox Eradication Program.  Smallpox eradication efforts began in 1967, the last endemic case appeared in 1977, and eradication was declared in May of 1980.  The declaration in 1980 that smallpox had been eradicated reawakened interest in disease eradication as a public health strategy. The smallpox program's success derived, in part, from lessons learned from the preceding costly failure of the malaria eradication campaign. Several biological, political, and social factors favored the eradication of smallpox, making the process relatively easy and quick compared to malaria eradication.(8)

The most important biological factors were that recurrent infectivity did not occur, there was no animal reservoir, and an effective vaccine was available.  Furthermore, infected individuals were easily identified due to the physical manifestation of disease symptoms.   In contrast to malaria, smallpox was easy to prevent, identify, and monitor.  In fact, management and surveillance were essential to the eventual eradication of smallpox.

My experience with smallpox eradication has shown that success occurs through strong management and proper coordination and that vertical programming can result in strengthened health-care infrastructures.” (9)Ciro de Quadros

Furthermore, there was substantial political motivation for the elimination of smallpox, as it was viewed as a disease that travelers might import into smallpox-free countries.  This provided a powerful stimulus for global eradication, allowing many resources to be allocated to the effort.  Yet smallpox eradication efforts often utilized coercion and “heavy-handed” strategies at end of campaign, specifically in South Asia.

“Coercion was justified by containment, but the containment concept was modified at least twice. Initially it simply meant vaccinating the known contacts of active smallpox cases…Containment was redefined in 1973 to mean that everyone in a village where active cases of smallpox had been detected had to be vaccinated, regardless of his or her prior immune status.” (10)

Unwarranted aggressiveness in delivering immunization was unsuited to building sustainable vaccination programs and coercion often left behind a residue of resentment that soured public attitudes toward future vaccination campaigns.  The same ethical standards of immunization followed in the developed world must be followed in the developing world as well.  It was later recommended that vaccination should be made compulsory, but exemptions should be allowed on the basis of proven religious or conscientious objections.

The achievement of smallpox eradication resulted not from possession of a magical new weapon such as a new vaccine, but from global cooperation.   It was based on old epidemiologic techniques, including intensive surveillance and disease reporting.  The way in which forces were marshaled on a global scale and applied to focused immunization at every local outbreak eventually led to victory. (11)

Conclusion

With wisdom beyond his time, Ronald Ross—the British officer who was the first to demonstrate that malaria parasites could be transmitted from infected patients to mosquitoes—wrote in 1911 that “malaria can be completely extirpated in a locality by the complete adoption of any one of the three great preventive measures, namely personal protection, mosquito reduction, and treatment”.  Ross also realized, however, that ‘it will never be possible for any general community to adopt or enforce any one of these measures completely’, that ‘all the measures are good and useful, and that each is most suitable under certain circumstances’, and that ‘these truths still continue to apply if we adopt not one single measure, but several combined’.(12)  To a great extent, these lessons still apply to the eradication of infectious diseases today, almost a century after Ross stated them at the Liverpool School of Tropical Medicine.

Given the mixed success of past eradication attempts, it is crucial to develop and evaluate current interventions in light of historical lessons.  Indeed, the age old adage that "those who cannot remember the past are doomed to repeat it" has a health corollary: the attitude that infectious disease is a problem easily remedied by advances in modern medicine and technology leaves us alarmingly vulnerable. 

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Footnotes

(1) Burattini, M. N., E. Massad, and F. A. B. Coutinho. 1993. Malaria transmission rates estimated from serological data. Epidemiology and Infection 111, (3) (Dec.): 503-23.

(2) The world health organization program to rid the world of malaria. 1959. The American Journal of Nursing 59, (10) (Oct.): 1402-4.

(3) Stapleton, Darwin H. 2004. Lessons of history? anti-malaria strategies of the international health board and the rockefeller foundation from the 1920s to the era of DDT. Public Health Reports (1974-) 119, (2) (Mar. - Apr.): 206-15.

(4) World Health Organization 1978. Malaria Control Strategy. Report by the Director General. Document A31/19. Geneva: WHO.

(5) Litsios, Socrates. Malaria control, the Cold War, and the postwar reorganization of international assistance. Medical Anthropology. 1997;17:255-78.

(6) World Health Organization 1978. Malaria Control Strategy. Report by the Director General. Document A31/19. Geneva: WHO.

(7) Packard, Randall. "Malaria Dreams: Postwar Visions of Health and Development in the Third World," Medical Anthropology 17 (1997): 279-296.

(8) Fenner F, Henderson DA, Arita I, Jezek Z, Ladnyi ID. Smallpox and its eradication. Geneva: World Health Organization; 1988.

(9) Quadros, C. “The Whole is Greater: How Polio was Eradicated from the Western Hemisphere.” In: Perlman and Roy. (Ch. 3).

(10) Paul Greenough, "Intimidation, Coercion, and Resistance in the Final Stages of the South Asian Smallpox Eradication Campaign, 1973-1975," Social Science and Medicine, Vol. 41, No. 5 (1995), 633-645.

(11) Glokpor GF, Agle AN. Epidemiological investigations. Smallpox Eradication Programme in Togo: 1969. Geneva: World Health Organization (WHO/SE/70.21); 1970.

(12) Stapleton, Darwin H. 2004. Lessons of history? anti-malaria strategies of the international health board and the rockefeller foundation from the 1920s to the era of DDT. Public Health Reports (1974-) 119, (2) (Mar. - Apr.): 206-15.