Recent advances on avian influenza ecology

The ecology of influenza A viruses, beginning with the Zoogeographic Region, is always related to the biological characteristics of the reservoirs and the eventual role of the epiphenomena. The ecology of influenza viruses is a very dynamic system in which certain structural constants (reservoir migrations) and other important environmental variables coexist. This system influences both the biology of reservoirs and that of epiphenomena, and in turn their interactions with the virus. High viral loads in feces of infected birds allow fecal-oral transmission. However, this route does not fully account for the efficiency of avian influenza virus (AIV) spread since dilution of infectious feces in water progressively decreases the chances of virus/host interaction. Recent studies showed that preen oil gland secretion, by which all aquatic birds make their feathers waterproof, could support a natural concentration mechanism of AIVs from water to birds’ bodies, thus favouring virus spread and persistence in the aquatic environment. We demonstrate a novel viral transmission route that adds to, and possibly contributes to explain the knowledge of long-distance movements and long-term infectivity of lowly and highly pathogenic AIVs in nature.