Over the past two years, around a hundred countries around the world have reported outbreaks of bird flu highly pathogenic (H5N1). And what worried the international scientific community was not only the recent report of the virus in cattle, together with the finding of genetic material in unpasteurized bovine milk (thus demonstrating resistance to pasteurization temperatures), but also the continuous spread of the virus across the five continents, including mammals such as minks, bears, foxes, seals and sea lions, but also dogs and cats, and even some endangered species.
What does it mean? Simply that more and more species are susceptible to the virus, that the host spectrum expands month after month and that, based on the lessons left by the latest pandemic, the more a virus is able to circulate between animal species, the more it can undergo mutations, improving its adaptability.
How much should man worry? In the last twenty years they have been reported less than a thousand cases of H5N1 infection (one recently in Texas), but with a very high mortality rate (52%) and with a marked neurotropism of the virus, that is, with a marked affinity towards the cells of the nervous system. Fortunately, however, no cases of human-to-human contagion have been reported: therefore human-to-human transmission does not yet appear to occur. We don’t know if this eventuality will ever occur, but since it is an influenza virus, traditionally capable of undergoing strong genetic recombination, it is right to follow the problem carefully.
For this reason, eco-epidemiological surveillance is of vital importance: following the evolution and habitats of the virus, as well as monitoring and evaluating transmission mechanisms, is essential to help plan epidemic intervention and management plans. Without forgetting that 70% of emerging infectious diseases affect humans originate from the animal worldso history teaches that the risk to human health remains potential but, as stated by the World Health Organization (WHO) and the World Organization for Animal Health (WOAH), not entirely impossible.
For this purpose, collaboration between the various sectors of animal and human health should be encouraged, in what would truly be an example of a One–Health.
