Topic: Under what conditions can a disease be successfully eradicated?

Introduction

Medically speaking, a disease is defined as a particular abnormal condition, a disorder of a structure or function that affects part or all of an organism, according to the World Health Organization (WHO). A disease is often regarded as a medical condition linked with specific symptoms and signs.

Eradication can be defined as the reduction of an infectious disease's prevalence in the global host population to zero. It is often mistaken as elimination, which describes either the decrease of an infectious disease's prevalence in the population of a region to zero or the reduction of the global prevalence to a negligible level.
The selection of diseases for eradication is based on various criteria, as both biological and technical features determine whether or not, a pathogenic organism is eradicable. The target must not have a non-human reservoir, and exaggerate in the environment. This connotes that sufficient information on the growth and transmission dynamics of the parasite is available at the time an eradication programmed is initiated. The disease to be eradicated should be clearly identifiable, and accurate diagnostic tools should exist. Economic, societal considerations and political support and commitment, are other essential factors that determine the feasibility of eradication.

Elimination and eradication of diseases

Elimination and eradication of human diseases have been the subject of a horde of conferences, workshops, symposia and public health initiatives for more than a century. While some of the eradication programmes of earlier years were unsuccessful, they contributed vastly to a better understanding of the biological, political, social and economic difficulties of achieving the final goal in disease control. Smallpox has been eradicated now, and other programmes are currently going on to eradicate poliomyelitis and guinea-worm disease.
Principal Indicators of Eradicability

Theoretically, all infectious diseases would be eradicable. In reality, there are different biological features of the organisms and technical factors of dealing them that make their potential eradication almost difficult. Three indicators were considered to be of primary importance:

a) an effective intervention is available to interrupt transmission of the agent;

b) practical diagnostic tools with sufficient sensitivity and specificity are available to detect levels of infection that can lead to transmission; and

c) humans are needed for the completion of the life-cycle of the agent, which has no other vertebrate reservoir and does not amplify in the surroundings.

The effectiveness of an intercession tool has both biological and operational attributes. Highly developed levels of sanitation and health systems development may make elimination possible in one geographical area but not in other areas.

Diagnostic tools also possess both biological and operational dimensions. The tools must be sufficiently sensitive and specific to detect an infection that may lead to transmission, and also sufficiently simple to be used globally in laboratories with a plethora of capabilities and resources.
Eradication is a feasible target of considerable intervention when humans host the microbe's life-cycle. An independent reservoir is not a roadblock to eradication if it can be targeted with effective intervening tools.

Economic Criteria

Conventional economic analytical techniques are not ideally suited to eradication programmes. It is unclear, for example, how to handle future benefits and cost, particularly long-term effects. Amongst the available techniques, the cost-effectiveness appeared to be the most useful when the outcome is expressed in health terms. It allows evaluation of disease eradication in relation to other health sector projects.

The costs and benefits of global eradication programmes can be classified into two categories -
A. direct effects and
B. consequent effects.

The direct effects are that no diseased cases or deaths would reoccur due to that disease. Control programmes can be ceased. The consequent effects are those that impact in either ways on the entire health care system. Precise efforts should be put in to optimise the effectiveness of both eradication and comprehensive health programmes.

Social and Political Criteria

A set of social and political criteria are summarised as follows:

• The success of a disease eradication programme is largely dependent on the degree of societal and political commitment to it from the beginning untill the end. Considering the potentially tremendous chances of failure, any proposal for eradication must be scrutinised intensively.

• The disease considered for eradication should be of public health importance, with broad international appeal, and be accepted as a worthy goal by all levels of society. There must be specific reasons for eradication.

• A technically viable intervention and eradication protocol must be identified, field-tested in a limited geographical area, and proven effective. The achievement of success in individual countries or within a region generates the momentum needed for international support.

• Political commitment must be gained at the optimum, following informed discussion at regional and local levels. A clear-cut commitment of resources from international sources is necessary from the start. World Health Assembly should make required resolutions for the success of any eradication programme.

In most of the cases, the problem is not that eradication programmes function too well but that primary health centres do not function well. Efforts are necessary to identify and qualify those factors responsible for amended functioning of eradication campaigns, and then apply them to primary health.
Conclusion

Microbes are dynamic and lively. They disperse locally, regionally, nationally and globally with ease in our centralised world, and when they find susceptible populations they re-emerge as public health problems. Surveillance and protraction of control measures are necessary to maintain accomplishments in infectious disease control unless transmission has been disrupted and the pathogen destroyed worldwide.

In summary, elimination and eradication programmes are commendable goals, but they carry with them a great responsibility. There is no room for failure. Cautious and deliberate evaluation is a prerequisite before venturing on any programme. Elimination and eradication of diseases are the superior goals of public health. The question is, whether these are to be achieved in the present or some near future.