Starting from the principled similarity and possibilities of variation of the antigenic components (Figure 1) of type A influenza viruses extremely widespread in nature, the author discusses the role and importance of avian influenza within the influenza entity. Based upon the two external antigens, at present 14 haemagglutinin and 9 neuraminidase subtypes or serotypes are known (Table 1). The influenza viruses, isolated in Hungary, at the Veterinary Institute of Debrecen since 1969 are grouped by subtype and avian species in Table 2. Influenza studies conducted in South China and Northern America suggest that waterfowl act as the natural reservoirs of influenza virus, which is explained by the high incidence of symptomless infection, the intestinal form, and by the aquatic origin of life. Although influenza viruses mostly persist in the species to which they have adapted themselves, they may cross the species barrier. With regard to the animal kingdom and humans, this is most likely to occur in South China, a region considered to be an influenza epicentre, where the transmission of influenza viruses from waterfowl to men most probably takes place through pigs, after much variation (Figure 2 and Table 3). Namely, in that region the close coexistence of the three species, the high density of the human and animal population, the optimal climatic and geographic conditions and the existing high susceptibility create a possibility for a chain of infection to develop. This is why avian influenza, especially the influenza of waterfowl, has great importance both in historic perspective and at the present time.
|Number of pages||6|
|Journal||Magyar Allatorvosok Lapja|
|Publication status||Published - Dec 1 1997|
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