Disease Elimination and Eradication

Disease elimination as a public-health problem means reducing a disease's burden below a specified threshold at which it is no longer considered a major public-health problem. Eradication means permanently reducing the worldwide incidence of infection caused by a particular disease agent to zero through deliberate efforts. The essential distinction is that elimination as a public-health problem can coexist with continuing cases and transmission, whereas eradication requires global absence of new infections.

What elimination as a public-health problem means

This is a threshold-based target, not necessarily a zero-case target. Its achievement is assessed using disease-specific indicators within a defined geographical area.

• For leprosy, the elimination threshold is a registered prevalence below 1 case per 10,000 population; meeting this threshold does not mean that transmission has stopped.
• Achievement at the national level can coexist with higher disease burdens in particular districts or communities.
• Continued interventions remain necessary, including case detection, treatment and surveillance, to sustain the achievement and address remaining disease.

What eradication requires

Eradication is a global and permanent endpoint. A country cannot independently eradicate a disease in the strict public-health sense while infection continues elsewhere.

• The target is zero worldwide incidence of infection, rather than a burden below an acceptable threshold.
• Once eradication is securely established, routine interventions needed to prevent natural transmission are no longer required.
• Smallpox, declared eradicated in 1980, is the standard example of successful human disease eradication.

Why the distinction matters for health programmes

Elimination of transmission is another distinct endpoint: it means reducing new infections to zero in a defined geographical area, while measures remain necessary to prevent re-establishment. It should not be confused with elimination as a public-health problem.

• Programme assessment must specify the indicator, threshold and geographical area before claiming that elimination has been achieved.
• An elimination declaration should not lead to withdrawal of diagnostic and treatment services, because residual disease and transmission may remain.
• Equitable access to surveillance, diagnosis and treatment matters because an aggregate target can conceal underserved populations with substantial disease burdens.