Surveillance of orthopoxvirus infections, and associated research, in the period after smallpox eradication.

In 1980, the World Health Assembly declared the global eradication of smallpox and recommended the universal discontinuation of smallpox vaccination; nevertheless, it recommended that surveillance and research on orthopoxvirus infections should continue. By early 1982, all except 8 countries in the world had stopped routine vaccination programmes and all except 1 no longer required an international certificate of smallpox vaccination for travellers. Since 1978, as a result of continuing active surveillance, 176 smallpox rumours have been investigated in 60 countries. Two of these concerned the two laboratory-associated cases that occurred in the United Kingdom in 1978; all the others were false alarms. Special surveillance programmes for human monkeypox have been developed in West and Central Africa. The number of laboratories retaining variola virus stocks has been reduced to four. Investigations to determine the identity and origin of the six known isolates of "whitepox" virus have continued. Research on mapping of variola DNA and on monoclonal antibodies against certain orthopoxvirus antigens is continuing. All these measures are aimed at ensuring that the achievement of smallpox eradication is permanent.