Revue scientifique et technique
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Influenza is a highly contagious, acute illness which has afflicted humans and animals since ancient times. Influenza viruses are part of the Orthomyxoviridae family and are grouped into types A, B and C according to antigenic characteristics of the core proteins. Influenza A viruses infect a large variety of animal species, including humans, pigs, horses, sea mammals and birds, occasionally producing devastating pandemics in humans, such as in 1918, when over twenty million deaths occurred world-wide. ⋯ Pigs have been considered the leading contender for the role of intermediary because these animals may serve as hosts for productive infections of both avian and human viruses and, in addition, the evidence strongly suggests that pigs have been involved in interspecies transmission of influenza viruses, particularly the spread of H1N1 viruses to humans. Global surveillance of influenza is maintained by a network of laboratories sponsored by the World Health Organization. The main control measure for influenza in human populations is immunoprophylaxis, aimed at the epidemics occurring between pandemics.
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West Nile virus (WNV) has emerged in recent years in temperate regions of Europe and North America, presenting a threat to both public and animal health. The most serious manifestation of infection is fatal encephalitis in humans and horses, as well as mortality in certain domestic and wild birds. ⋯ During this outbreak, mortality was observed in humans, horses, a cat and numerous species of wild birds, particularly members of the family Corvidae (crows). The author reviews basic information and summarises recent developments in the epidemiology and epizootiology of WNV.