Disease Eradication

In many areas, disease is a significant barrier to development and there are numerous examples where elimination of a disease (the reduction of its incidence to zero in a defined geographical area) has provided significant economic benefits as well as increases in well-being.

The extension of this concept to the actual eradication of a disease - i.e., the permanent reduction to zero of the world-wide incidence of infection caused by a specific agent - has the obvious attraction that, if achieved, intervention measures are no longer needed. However, there are those who see such efforts as taking desperately needed resources away from basic health services.

The eradication of smallpox is the exemplar of the success of this approach. It has been estimated that some 350 million new infections, with 40 million deaths, would have occurred in the past twenty years if it had not been eradicated. This is, however, misleading, since it assumes 1967 incidence rates, and significant reduction in these rates could well have been achieved without an eradication campaign..

The special features of smallpox - its easy diagnosis, the lack of any reservoir or vector outside humans, the immunological simplicity of the virus and the existence of an effective vaccine - must also be borne in mind.

The failure of earlier campaigns should also be examined. Campaigns to eradicate yaws and malaria both began about 1955. Both floundered on ignorance of the natural history of the disease. In the case of yaws, the fact of a high prevalence of subclinical infections was not discovered until ten years into the programme. With malaria, it proved possible to interrupt transmission and eliminate the disease only in regions where favourable climatic and human factors existed.

Perhaps an even bigger problem with attempts to eliminate malaria in developing regions was the completely vertical approach adopted, with a demand for absolutely standardised (and frequently inappropriate) operations and a lack of community involvement.

To an extent, these lessons have been learned in the current campaigns to eradicate polio and measles. There is more flexibility in approach, more community involvement and more continuing research into effectiveness of procedures.

These campaigns have apparently been quite effective in eliminating the target diseases from certain regions but there are grounds for scepticism regarding the reaching of target dates for eradication. In the case of polio, there are pockets which are proving very difficult to reach, especially in areas of civil unrest in Africa, and the virus may be shed for prolonged periods in oral vaccine recipients and has, in some instances, reverted to virulence.

Despite this, there are some who would argue that the campaign to eradicate polio, even if ultimately unsuccessful, will have conferred considerable benefits. Firstly, there is the obvious human and economic benefit of the large reduction in morbidity and mortality that has been obtained.

In addition to this, eradication brings improved and additional advocacy and mobilisation of financial and human resources at global, national and local levels and from public and private sources, for both eradication-related activities and basic services. It frequently leads to an expanded role of the private sector in public health.

It may strengthen national health policy development, increase transparency and broaden the commitment to health. The systematic introduction of targets and indicators and mechanisms for delegating authority to districts may strengthen institutional arrangements.

The introduction of performance-based incentive models and the co-ordination of a strong training component with national plans may provide an ongoing benefit.

Programs set up under eradication campaigns can increase access to, and utilisation of, health services. They can establish surveillance as a key tool in disease control. For example, the majority of African countries use resources (including the laboratory specimen transport system) set up for the polio campaign also for surveillance of, and response to, other infectious diseases. Again, polio surveillance systems in Latin America were helpful in determining the scope of cholera outbreaks in the early 1990s, while the global polio laboratory network is a model for global infectious disease laboratory surveillance..

Another benefit of the global polio eradication campaign is its role in expanding computer capacity and the development of health information systems in developing countries.

Perhaps the greatest benefit has been the increase in enthusiasm for immunisation and other public health programs engendered in local and political officials by the success of polio eradication activities.

Enthusiasts claim that incidental benefits from the dracunculiasis (Guinea worm) eradication campaign exceed the direct effects from the reduction in cases. They point to improvements in agricultural production, school attendance, infant nutrition, care and immunisation, and the establishment of community-based health education, mobilisation and surveillance and claim that the Guinea worm eradication programme has probably done more to improve health care in some communities than primary health care programmes.

On the other hand, eradication campaigns may divert financial and human resources from basic services and from research. They may compromise local decision making by imposing external priorities and even result in the establishment of parallel structures. Personnel may be diverted and subjected to uncoordinated in-service training. Routine service delivery may be disrupted.

The best summation might be that eradication and elimination activities can make substantial contributions to sustainable health development but that such activities must be designed in such way that they provide maximum benefits to national health systems.