The EU's Food Safety Agency (EFSA) warned on Wednesday of a large-scale bird flu pandemic if the virus becomes transmissible between people as humans lack immunity against the virus.
This comes a day after Texas reported that the H5N1 strain of avian influenza, commonly known as bird flu, had been detected in a person who had contact with dairy cows presumed to be infected with the virus.
The spread of bird flu is a concern for governments and the poultry industry due to the devastation it can cause to flocks, and a risk of human transmission.
The number of bird flu outbreaks has been lower so far this season but it spread geographically, including to Antarctica, and to an increasing number of mammals, raising the risk of it evolving into a bigger threat to humans.
To date there has been no sustained human-to-human transmission observed and bird flu transmission from infected animals to humans is rare.
However, these viruses continue to evolve globally, and with the migration of wild birds, new strains carrying potential mutations for mammalian adaptation could be selected, EFSA said.
"If avian A(H5N1) influenza viruses acquire the ability to spread efficiently among humans, large‐scale transmission could occur due to the lack of immune defences against H5 viruses in humans," EFSA said in a report.
Some 887 cases of human infection with H5N1 avian influenza, were reported globally between January 2003 and Feb. 26 this year, the World Health Organisation (WHO) said in its latest report. Of these 462 were fatal, accounting for a rate of 52%.
The majority of human cases were detected in people with unprotected exposure to sick or dead poultry, live poultry markets or a contaminated environment.
Wild mammals could act as bridge hosts between wild birds, domestic animals and humans, EFSA said. Companion animals, such as cats living in households and with access to the outdoors, could also be a potential vehicle for transmission, it added.
In addition to poultry and dairy cows reported in the United States, mammals hit by the virus include goats, cats, foxes, racoons, skunks, polar and grizzly bears and elephant seals.
EFSA called for enhanced surveillance for humans and animals, ensuring access to rapid diagnostics, promoting collaboration between the animal and human sectors and implementing preventive measures such as vaccination.
