Disease Elimination and Eradication

Disease Elimination and Eradication

Introduction

Elimination and the eradication of the human disease have been the subject of numerous conferences, workshops, planning sessions, and public health initiatives for more than a century. Although the malaria, yellow fever, and yaws eradication programmes of earlier years were unsuccessful, they contributed greatly to a better understanding of the biological, social, political, and economic complexities of achieving the ultimate goal in the disease control. Smallpox has been eradicated and programmes are currently under the way to eradicate poliomyelitis and guinea-worm disease.

The ultimate objective of any communicable disease control programme is the elimination, and then the eradication, of the targeted disease.

Definitions

Elimination of disease is defined as the reduction of case transmission to a predetermined very low level at which the disease is no longer a public health problem, like with kala-azar, filariasis, leprosy and neonatal and maternal tetanus elimination. After elimination is achieved, the disease prevention and the control efforts should actively continue in order to maintain the elimination status. Interruption of the control measures will result in re-emergence of the infection or the disease in the previously free areas.

Disease eradication is defined as an irreversible cessation of transmission of the causative agent through extermination of this causative agent from all countries of the world. When a disease is eradicated, the infection disappears from the world, no further cases of the disease occur anywhere and continued control measures are unnecessary.

Principal Indicators of Eradicability

In theory, if the right tools were available, all the infectious diseases would be eradicable. In reality, there are distinct biological features of the organisms and technical factors to dealing with them that make their potential eradicability. Today's categorization of a disease as not eradicable can change completely tomorrow, either because research efforts are successful in developing new and effective intervention tools or because those presumed obstructions to eradicability that seemed important in theory prove capable of being overcome in practice. Three indicators were considered to be of primary importance: an effective intervention is available to interrupt transmission of the agent; practical diagnostic tools with the sufficient sensitivity and specificity are available to detect levels of infection that can lead to transmission; and humans are essential for the life-cycle of the agent, which has no other vertebrate reservoir and does not amplify in the environment.

The effectiveness of an intervention tool has both the biological and the operational dimensions. Elimination validates the effectiveness of an intervention tool, but it does not necessarily make the agent a candidate for the eradication. Highly developed levels of sanitation and health systems development may make elimination possible in one geographical area but not in another.

Diagnostic tools also have both the biological and the operational dimensions. The tools must be sufficiently sensitive and specific to detect theinfection that can lead to the transmission, and also sufficiently simple to be applied globally by laboratories with a wide range of capabilities and resources. Eradication is a much more convincing target of deliberate intervention when the humans form an essential component of the agent's life-cycle. The independent reservoir is not an absolute barrier to the eradication if it can be targeted with the effective intervention tools.

The control, elimination or eradication of a disease, depends on identifying the various factors related to its occurrence, as well as the availability and implementation of effective prevention and control strategies. The political environment, which defines the political commitment, availability of resources and national and international support, is also an extremely important factor.

Global goals for elimination and eradication of the disease are built on the experience gained from the successful eradication of smallpox in 1977. At present, the global and regional targets for communicable disease elimination and eradication include: poliomyelitis eradication by 2005 (regional and global target); leprosy elimination by 2005 (regional and global target); maternal and neonatal tetanus elimination by 2005 (regional and global target); visceral leishmaniasis elimination by 2015 (regional target, Bangladesh, India and Nepal) and lymphatic filariasis elimination by 2015 (regional target). Three of these targets were set for the end of 2005 (eradication of poliomyelitis and elimination of filariasis and maternal and neonatal tetanus).

Disease elimination and the eradication programmes can be differentiated from ongoing health or disease control programmes by the urgency of the elimination and the eradication programmes and the requirement for targeted surveillance, rapid response capability, high standards of the performance, and a dedicated focal point at the national level. Eradication and the ongoing programmes constitute a potentially complementary approaches to the public health. There are the areas of potential overlap, conflict and synergy that must berecognisedand addressed. In manycases,the problem is not that eradication activities function too well but that the primary health care activities do not function well enough. Efforts are needed to identify andcharacterizethose factors responsible for the improvedfunctioning of the eradication campaigns, and then apply them to the primary health.

References

Gordis, L. Epidemiology. third edition. 2004.

Joshi, Banjara. Fundamentals of Epidemiology. Kathmandu: Quality Printing Press, 2007

Park, K. Park's Text Book of social and prevention Medicine. 18th edition. 2008.