Scientists are raising the alarm about US cases of H5N1 in cows as transmission to humans is easier. Here in Europe, steps are being taken to prepare. A strain of bird flu that jumped to dairy cows and then farmworkers in the US this spring could become a global health risk – but the extent of the threat is unknown and officials in Europe and elsewhere could be caught unprepared if it escalates.
The US cases are the latest upswell of a highly pathogenic avian influenza (H5N1) that has been circulating among migratory birds and in recent years, mostly in Europe and the Americas. Since March, the strain has cropped up in 145 cattle herds in 12 US states and infected , all of whom went on to recover from their illnesses. There has been no evidence of human-to-human spread, which is a key marker of pandemic threat, while no human cases of the strain have been reported in Europe, and the European Centre for Disease Prevention and Control (ECDC) says is at low risk of infection.
Even so, experts say there are enough warning signs that European countries should already be monitoring the virus and getting ready to respond quickly if that changes. Waiting until the virus emerges among people on this side of the Atlantic would allow H5N1 to spread unchecked for long enough that it becomes difficult, if not impossible, to quash. “Things can change very fast, and it's difficult to put a precise timeline on it, because it depends on what the emergence process looks like,” Colin Russ.