Perspectives and limits in the eradication of infectious diseases

Eradication of an infectious disease on a global scale means that transmission of the disease has been completely vanished and the disease caused by the infection has totally disappeared. Regional eradication represents disappearance of an infection from a certain area or region whereas elsewhere it continues to be transmitted. Smallpox which was finally eradicated in 1977 had been progressively eliminated from one continent after another in the preceding years. At the present time regional elimination of paralytic poliomyelitis has almost succeeded in the USA, the United Kingdom, Europe and Asia through routine use of Sabin live oral vaccine. Paralysis associated with the use of this vaccine has continued with an extremely low incidence-rate. Contact-infection and spread of virus excreted by recently-vaccinated persons occur to a significant extent and fortunately with polioviruses mostly unchanged in virulence. The second disease with attempted regional elimination is measles. In the USA county-wide elimination was successful in 1985 in all but a minority of counties. There followed two years with many more cases before a decline in incidence resumed once again. Elsewhere the general sponsoring of immunization under the expanded programme (EPI) of WHO is slowly taking effect.