Spillover of highly pathogenic avian influenza virus H5N1 to dairy cattle
Professor Dr. Salah Mahdi Hassan,
Professor of Poultry Diseases / Poultry Health and Care Expert,
8/8/2024
A recent study published in Nature magazine on 25/7/2024 showed an in-depth analysis of the clinical , pathological and epidemiological properties of unprecedented transmission of highly pathogenic avian influenza virus (H5N1) to dairy cattle in many state in the USA.
The study was under name ( spillover of the highly pathogenic avian influenza virus H5N1 to dairy cattle) .The study showed the clinical signs that monitored on cows, which began to decrease of feed intake, a change in the components of bio-waste of cattle, and great difficulties in respiration, droop in milk production, which is often accompanied by change in both the color and the nature of milk .
A detailed analysis, of the complete virus sequencing of the isolated viruses, from different types of cows, in infected farms, the presence of the complex infection pattern between cow species, which was determined on the ability of the virus to cross species barriers.
The isolation of the virus was done from milk produced by infected cattle and from different tissues, with a sign that there was a high-quality presence of the causative virus in the epithelial tissues of the udder of infected cows.
The study show evidence of the presence of evidence suggests that isolated viruses are transmitted between cattle, as demonstrated by a case that occurred in cattle herds after healthy cattle were entered to the farm from infected herds in another state. This critical note highlights the state of the ability of infected cattle by the virus and with no signs of clinical signs, of transmission the disease to other farms, and thus will be of great concern to the efforts that try to contain the disease. As the study reported the presence of the causative virus in 6 of 19 original nasal samples, and in 4 of 8 urine samples, from apparently healthy cattle, which confirms its current subclinical carrier.
The H5N1 virus has caused losses in the most recent major outbreak recorded in domestic and wild birds, since its appearance in the United States in 2022, resulting in a great loss of millions of birds, and quickly became the causative virus that is very severe in mammals, where there was reports of infection in cats, red foxes, bears, seals and even polar bears.
The current study has added to the list, this case by providing the first known outbreak in cattle . The research specifically identified a new discovery gene of the virus B3.13, which combines the remaining Eurasian wild bird and American bird strains. The reduction revealed that the strains of the virus isolated from cattle are closely related, suggesting routes of transmission between farms and between species, including from cattle to cats and raccoons.
The animal susceptibility of the virus is a looming concern, especially as it adapts to new hosts, which could increase the risk of pandemics.
Finally, the article published by ( Caserta et.al., 2024) is a comprehensive analysis of the H5N1 virus in milk cows, its transmission tactics, the urgent need to take action to prevent further spread, and the potential risks to human health.
https://www.nature.com/articles/s41586-024-07849-4
