[Circulation of virus and interspecies contamination in wild animals]

Paradoxically, just when we have succeeded in eradicating and/or bringing under control the major viral infections (smallpox, poliomyelitis, measles) numerous viral infections are emerging in man and in animals. Changes in our social environment, technological and ecological equilibrium have facilitated this phenomenon. Furthermore, certain of these viruses have demonstrated an almost unlimited capacity to adapt genetically to environmental change. HIV has already infected 40 million individuals, but monkeypox, Ebola, simian herpes can cause epidemics with serious if not fatal outcomes. Haemorrhagic fever epidemics have resulted from human contact with Flavivirus infected rodents and insects. Paramyxoviruses and morbiliviruses can cause fatal outcomes in man and animals. And the three influenza epidemics having occurred in the 20th century all came from the type A avian reservoir. The often complex combinations of predisposing factors having facilitated the emergence of several epidemics merit further consideration.