Understanding the Ecology and Epidemiology of Avian Influenza Viruses: Implications for Zoonotic Potential

摘要

Influenza originally referred to epidemics of acute, rapidly spreading catarrhal fevers in humans which have subsequently been shown to be caused by an orthomyxovirus (41). Today, orthomyxoviruses are known to cause significant numbers of natural infections and disease in humans (Homo sapiens), horses (Equus caballus), pigs (Sus scmfa) and various bird species, and sporadic cases of naturally occurring disease in mink (Mustela vison) and various marine mammals (24,52,91). However, there is additionalevidence to suggest the potential for other mammals to be infected based upon experimental studies and serologic surveys of domestic, laboratory and wild mammalian populations (10,64). However, rodents, carnivores and ungulate ruminants do not appear tobe natural reservoirs nor are they involved as biological vectors of influenza virus transmission between animal species experiencing endemic influenza. In general, influenza viruses replicate in epithelial cells of the upper respiratory tract or gastrointestinal tract and outcomes of such infections include no clinical signs, upper respiratory disease, pneumonia and occasionally death. In birds, most infections are subclinlcal. However, in poultry, influenza infections have caused clinical respiratory disease or drops in egg production, and a few specific avian influenza virus strains have caused severe disseminated infections with systemic disease and high death losses (21).