#18,582
While there are good reasons to believe that some (perhaps, many) cases have gone undetected, the above graph showing the uptick of confirmed human H5N1 infections in the Americas since last fall suggests the virus is gaining momentum.
In early December, PAHO (the Pan American Health Organization) released a 20-page Epidemiological Alert: Human Cases of Avian Influenza A(H5N1) in the Americas Region - 3 December 2024, which urged that member states `. . . ensure preparedness for a potential influenza pandemic at all levels (14, 15).'
In early January PAHO unveiled their Interactive Dashboard To Monitor HPAI H5 In the Americas.
Yesterday PAHO released a new, updated, 32-page Epidemiological Update on H5N1, which summarizes HPAI H5 activity (primarily in the Americas) during 2024, and once again calls upon Member states to proactively prepare to deal with a potential influenza pandemic.PAHO/WHO urges Member States to work collaboratively and intersectorally to preserve animal health and protect public health. It is essential that avian influenza preventive measures be implemented at the source, protocols for detection, notification, and rapid response to outbreaks in animals be established, surveillance for both animal and human influenza be strengthened, epidemiological and virological investigations be carried out in relation to animal outbreaks and human infections, sharing of genetic information about viruses, fostering collaboration between animal and human health settings, effective risk communication, and ensuring preparedness for a potential influenza pandemic at all levels (24, 25).
While surveillance and reporting from vast swaths of Northern Canada, and much of the interior of South America are limited, the level of activity (in birds, mammals, and humans) reported in the United States over the past year (see below) illustrates how pervasive the virus has become.
Much of this document deals with specific advice for public health agencies in Member states; on the identification, testing, investigation, and reporting of HPAI H5 cases. Other sections deal with reagents and laboratory testing algorithms, the sequencing of viruses, and the management of human cases.
Of course, we've stood on the precipice before with H5N1, only to see the virus retreat. That could well happen again. But it is fair to say that this time `feels' different.
The clade 2.3.4.4b virus has managed to spread across 90% of the globe, and has not only expanded its avian host range, it has made huge inroads into mammals (see examples below).
But the simple fact is we've seen it has happen at least twice before (the 1957 H2N2 pandemic, and the 1968 H3N2 pandemic), where an avian virus reassorted with seasonal flu, producing a new, easily transmitted hybrid.
The only thing certain is that another pandemic will come. And any preparations we make now due to concerns over H5N1, could pay big dividends later.
