[Achievements and failure of WHO during realization of the control programmes of the communicable diseases during twentieth century].

Eradication of smallpox in 1977 in the world was the greatest achievement of the health status of the world population. It is also greatest cost benefit achievement not only in the health control programmes, but also in general economy. This achievement was possible from from two main reasons: (a) because vertical, well organized programmes was implemented and (b) during realization of the program change of strategy was introduced.