A highly virulent, and prevalent among birds, strain of avian flu has been detected in dairy cows in Nevada, according to the USDA Animal and Plant Health Inspection Service (APHIS). This has put public health officials on the alert as fear it could mutate and spread to more people. So far there have been 67 cases of the disease in humans, and one death.
H5N1 emerged in 1997 and since then, has spread globally by migratory birds, resulting in infections in animals on every continent. Most of the U.S. infections to date have been among people who work with birds or cows.
Scientists say these new cow infections with a different type of virus mark an inflection point in the nation’s efforts to contain the virus: It may be here to stay.
The Nevada cow infections are the first detection of H5N1 D1.1 in dairy cattle. All previous detections in these animals have been H5N1 clade 2.3.4.4b, genotype B3.13. Genotype D1.1 is the predominant genotype found in animals so far. It has been identified in wild birds, mammals, and spillovers into domestic poultry.
Luckily, the prospects for vaccines are good if needed, “current vaccine candidates neutralize the circulating strains in vitro, and these strains so far are susceptible to antiviral agents. Studies have shown the safety and immunogenicity of A(H5N1) vaccines and the need for a two-dose prime–boost approach and use with adjuvants,” wrote Ison, MG, et al. in their Dec. 24 NEJM.
They added that, “Work is ongoing to complete candidate vaccines for clinical use, if needed. Furthermore, studies are ongoing to develop messenger RNA–based A(H5N1) vaccines and other novel vaccines that can provide protection against a broad range of influenza viruses, including A(H5N1). Circulating isolates are susceptible to ll approved neuraminidase inhibitors, adamantanes, and baloxavir marboxil.”
HPAI says these infections in Nevada do not change its eradication strategy, but “…is a testament to the strength of our National Milk Testing Strategy (NTMS). In the interest of sharing information of import to the scientific community, APHIS will publish a technical brief on the findings on our website and post the sequence data on GenBank in the coming week.”
This development also highlights the need for more interagency cooperation and genomics, and the urgent need to be vigilant of emerging mutations and regular assessment of the threat of human-to-human transmission.
Additional on-farm investigation, testing, and gathering additional epidemiological information to better understand this detection and limit further disease spread.
