There are two most important aspects that make it possible to hypothesise that intensive animal husbandry even plays a role in preventing the passage of influenza viruses from animals to humans:
- A first important aspect: in past centuries, the world’s population lived in rural areas in close contact with various species of domestic poultry and pigs, which favoured contagion and viral reassortment between humans and animals. Since the advent of intensive livestock farming, the vast majority of the population has shied away from direct contact with animals, leaving this task to a few insiders: the possibility of new pandemic influenza viruses emerging has consequently been greatly reduced.
Furthermore, if we take into account the cases of direct contagion between birds and humans in recent decades, we realise that 99% of the cases occurred in rural environments in poor countries, where coexistence between humans and animals was similar to that of previous centuries. Fortunately, inter-human contagion has never occurred from these few cases so far, as the WHO has also stated.
- A second important aspect is that strict biosecurity procedures are put in place in intensive livestock farms, operators wear protective clothing, and above all, the network of periodic checks makes it possible to immediately identify the outbreak of influenza disease and to achieve its subsequent eradication. This was not the case in the rural world of past centuries and is still not feasible in those environments today.
The combination of these factors and actions clearly demonstrate the fundamental role that intensive livestock farming plays in the prevention of future human pandemics caused by influenza viruses of avian origin, contrary to the claims of animal welfare associations.
As for the spread of influenza viruses to wild birds from domestic birds, contagion is clearly possible, but it is mainly wild birds that infect domestic birds.
This is one of the reasons why birds on intensively protected farms are reared in enclosed buildings. It is known that free-range flocks have a risk of contracting bird flu hundreds of times higher than indoor flocks.
Historical studies on influenza epidemics have shown that highly pathogenic viruses were practically endemic in poultry in Europe, Asia and America from 1877 to 1958. At that time, intensive rearing of domestic poultry species did not exist and poultry production took place only and exclusively in rural environments: it is evident that these extensively reared domestic birds were perfectly capable of infecting wild birds, with an even greater capacity for infection, since they were reared outdoors.
In conclusion: the mutation of the influenza virus from low pathogenicity (typical of wild birds) to high pathogenicity (often found in domestic birds) occurs in nature regardless of the type of domestic bird husbandry (intensive or rural).
But intensively protected farms are indoors and therefore have a much lower chance of contracting bird flu than extensive free-range or rural farms.
We can therefore recognise an important role of intensively protected farms in preventing the spread of avian influenza and, consequently, in reducing the possibility of virus mutations capable of generating influenza pandemics in humans.
The editorial staff of M.A.C.
- AVIAN INFLUENZA: What really is bird flu? Who should we believe?
- AVIAN INFLUENZA: keeping birds indoors prevents pandemics
- AVIAN INFLUENZA: intensive farming prevents it
