In a current examine printed within the journal Rising Infectious Illnesses, researchers in Alaska, United States of America (US) reported a pure an infection of a extremely pathogenic avian influenza (HPAI) A(H5N1) or hen flu virus in a younger, free-ranging polar bear that was discovered useless in Alaska in 2023. They highlighted the importance of continued wildlife well being surveillance by the neighborhood in addition to by hunters within the Arctic.
Dispatch: Extremely Pathogenic Avian Influenza Virus A(H5N1) Clade 2.3.4.4b An infection in Free-Ranging Polar Bear, Alaska, USA. Picture Credit score: Alexey Seafarer / Shutterstock
Background
First detected in October 2020 in Europe, the HPAI A(H5N1) clade 2.3.4.4b virus has since typically contaminated varied mammal species globally ever since. In North America, pure hen flu infections have been noticed in a number of bear species, together with Asiatic black bears, American black bears, grizzly bears, and Kodiak brown bears. Animals in captivity, together with sloth bears, Asiatic black bears, and big pandas, have been reported to contract different influenza A(H1N1) viruses. Moreover, antibodies towards H3 and H6 influenza subtypes recommend earlier pure exposures to hen flu viruses. Notably, seroconversion has been famous in Barent Sea polar bears and Alaskan brown bears however not within the southern Beaufort Sea polar bears.
Curiously, genome evaluation of Alaskan wildlife influenza viruses has each unreassorted and reassorted strains. The HPAI virus genotype A3 was seemingly launched into Alaska by way of the East Asia–Australia Flyway in November 2021. Since then, it has been detected in varied wild birds, together with California condors in Arizona, and mammals resembling crimson foxes, fishers, martens, raccoons, and brown bears alongside the Pacific Flyway.
Polar bears (Ursus maritimus) are labeled as a threatened species beneath the US Endangered Species Act. Understanding their well being threats is essential for conservation efforts and growing efficient administration methods. Within the current examine, researchers report the case of a male polar bear naturally contaminated with the HPAI H5N1 virus that succumbed to the an infection.
Concerning the examine
The North Slope Borough Division of Wildlife Administration (NSB DWM) in Alaska researches wildlife well being and maintains packages for monitoring the harvest of marine mammals, together with polar bears, by the neighborhood. The Alaska Workplace of the State Veterinarian oversees wildlife surveillance for the presence of notifiable infectious illnesses. After figuring out HPAI H5N1 in birds of prey and a crimson fox in April 2022, the Workplace of the State Veterinarian started collaborating with NSB DWM for surveillance testing of avian influenza in birds and different wildlife.
Native residents reported discovering a useless polar bear close to Level Barrow, Alaska, in August 2023. A postmortem examination was carried out. The bear was discovered to be a 120 cm-long juvenile male in a situation of average to superior decomposition. After a gross examination, tissue samples had been collected and glued in 10% buffered formalin for histopathologic examination. Swab samples had been additionally collected and saved at −50°C. They had been processed for routine histopathologic examination with eosin and hematoxylin staining. Swab specimens had been examined for the influenza virus matrix gene by polymerase chain response (PCR). Immunohistochemistry was carried out utilizing an influenza A virus polyclonal antibody. Additional, molecular affirmation and virus genome characterization had been carried out.
Outcomes and dialogue
Gross examination revealed liver and lung congestion, ulcerative pores and skin lesions, sanguinal effusion, cerebral swelling and congestion, and an empty abdomen. The most important histopathologic findings had been granulocytic and mononuclear meningoencephalitis with microgliosis, neuronophagia, vasculitis, neuronal necrosis, and parenchymal rarefaction. Moreover, the researchers recognized focal lipid pneumonia, pulmonary edema, and multifocal ulcerative dermatitis. Swab specimens had been discovered to be unfavorable for the influenza virus matrix gene. Regardless of unfavorable PCR exams, immunohistochemistry detected influenza A virus antigen in neurons and microglial cells. Molecular evaluation recognized HPAI virus genotype A3, a Eurasian influenza virus. The virus was first detected in Alaska in April 2022 and was probably the most detected genotype within the area throughout August–December 2023. Full genome sequences for the virus infecting the polar bear had been deposited in GenBank and GISAID (brief for world initiative on sharing all influenza knowledge).
Conclusion
In conclusion, the invention of HPAI H5N1 in a polar bear signifies the virus’s skill to spill over into varied mammalian species, emphasizing the necessity for vigilant monitoring (each community- and hunter-based) of wildlife well being to detect rising pathogens early. The profitable detection of the virus via collaborative efforts between wildlife administration departments and state veterinarians highlights the significance of built-in surveillance methods in monitoring and responding to wildlife well being points. Since polar bears and different wildlife are integral to the subsistence way of life and meals safety of Indigenous communities within the Arctic, detecting HPAI H5N1 highlights potential zoonotic dangers. This requires methods to mitigate the impression on conventional meals sources and safeguard public well being. The findings present beneficial knowledge on the unfold and impression of HPAI H5N1 within the Arctic area, contributing to the broader scientific understanding of influenza virus ecology and cross-species transmission dynamics.
