Avian flu alert: Understanding the circulating influenza virus H5N1's threat

For a little over three years now, scientists have been tracking a genetically distinct influenza virus, originally affecting birds (avian influenza) and mammals in the Americas (Figure 1), that is now causing a widespread outbreak in cattle across the United States (US). Reports of 13 human cases from close contact with dairy animals in the US have cast a spotlight on the evolving nature and zoonotic potential of avian influenza viruses. These reports have also raised an alert in organisations working on pandemic preparedness across the world, advocating close monitoring and assessment of current threat levels. While the current avian influenza outbreak in the US poses a low public health threat due to limited human-to-human transmission, we should be attentive to the potential of this zoonotic virus to cause significant disruptions.