However, viruses that had acquired characteristics for spillover to humans were not only the highly pathogenic viruses, but also low pathogenic viruses, “that do not cause very serious disease, but can circulate in the population and slowly can acquire these mutations,” Broglia explained.
This makes surveillance on low pathogenic viruses “a cornerstone” to spot these mutations and characteristics that can lead to human adaptation, he said.
Test, test, test
Adaptation of avian influenza viruses to mammals can happen through genetic mutations and also through the mixing of genetic material between viruses. The interaction between wildlife, poultry, livestock and people is a driver for spillover.
“Are we creating the condition for this happening? What kind of poultry breeding system are we implementing? Why so many outbreaks in poultry farms in certain areas? And why so many jumps in mammal species?” Broglia asked, urging countries to think about how human activities facilitate the spread of such viruses.
There were close to 100 human infections last year, said Colzani at the ECDC. Those often happen in occupational settings, where humans are exposed to sick animals.
Colzani told POLITICO it would be “good practice” to test people when animal outbreaks occur — even if a person exposed to sick animals doesn’t show any symptoms “to detect if there is any silent transmission.”