The avian virus is causing fear again. The alarm was raised after there was the second human case of avian flu in the United States, in Texas, in a dairy worker who had come into contact with infected cattle. The person tested positive in the United States for the current H5n1 strain
of highly pathogenic avian influenza through dairy cattle.
The US Department of Agriculture confirmed on April 2 the presence of dairy cattle infected with the A/H5N1 avian influenza virus on a farm in Idaho. It is the fifth American state to be affected by the epidemic after Texas, Kansas, Michigan and New Mexico. Preliminary investigations have concluded that the virus strain detected in the latest case is similar to those previously found in the US states of Texas and Kansas and appears to have been introduced by wild birds.
So far there are no signs that the disease is spreading more easily between people, according to American officials. According to experts, authorities from different sectors should still work together in a One Health perspective to limit the exposure of mammals, including humans, to avian influenza viruses.
Is it safe to consume milk?
At the moment, the Statute authorities underline, the level of risk to human health remains low; however, people with close or prolonged, unprotected exposures to infected animals or contaminated environments are at increased risk of infection.
Federal officials have stressed that milk sold to the general public remains safe to drink. No worries regarding commercial milk “because the products are pasteurized before entering the market”, specifies the Agriculture Department.
A changing scenario
However, the scenario could change, especially in the European Union. The European Center for Disease Prevention and Control (ECDC) is convinced of this and, through the words of Angeliki Melidou, ECDC's main expert on respiratory viruses, launches a warning: “The transmission” of avian influenza “from infected birds to “Human influenza remains a rare event, with no confirmed human infections identified in the EU/European Economic Area. However, the possibility of avian influenza viruses adapting to humans and causing a pandemic remains a cause for concern.”
The alarm is already ringing in the Old Continent. “The avian influenza virus continues to spread in the European Union, and elsewhere, causing high mortality among wild birds, spillovers (i.e. species jumps) between wild and domestic mammals and outbreaks on farms.” This is highlighted by the European Food Safety Authority EFSA, in a note which takes stock of what emerges from a scientific report signed together with the European Center for Disease Prevention and Control (ECDC), in which the risk factors for a potential influenza pandemic and related mitigation measures.
The risk of spillover
What conditions could drive viral evolution? Experts have identified certain species of farmed fur animals (e.g. mink or foxes), which are highly susceptible to influenza viruses, as possible spread factors. “Although mammal-to-mammal transmission has not yet been confirmed, wild mammals could act as 'bridge' hosts between wild birds, domestic animals and humans. Even companion animals, such as cats, that live in home and have access to the outside, in open air environments, can be a potential vehicle of transmission”, warn the European authorities.
Farming in areas rich in aquatic birds, with outdoor production and/or poor biosecurity, “may facilitate the introduction of the virus into farms and its further spread”, continues EFSA. “Extreme weather events and climate changes – he underlines – play an additional role in the evolution of the situation because they can influence the ecology and demography of wild birds and therefore influence how the disease develops over time, experts have found “.