A/H5N1 outbreak in Argentine Elephant Seals suggests mammal-to-mammal transmission
A new study published in Nature Communications investigates the outbreak of highly pathogenic avian influenza (HPAI) H5N1 in marine mammals, specifically elephant seals, along the coast of Argentina from 2022 to 2023. It highlights the alarming spread of the virus among marine mammals and its connections to outbreaks in other South American countries. The study employs phylogenetic analysis of H5N1 virus genomes from various species to understand the transmission pathways and genetic characteristics of the virus. The researchers identify significant pathways of H5N1 virus spread among marine mammals in South America, emphasizing the interconnectedness of outbreaks across countries such as Argentina, Brazil, Chile, Peru, and Uruguay.
Phylogenetic analysis reveals that the strains affecting marine mammals in Argentina are closely related to those found in avian hosts and other mammals in the region, indicating a potential for cross-species transmission. The genomic analysis shows that the viruses from pinnipeds (seals) and terns form a distinct clade that shares a set of mammalian adaptation mutations. This genetic similarity supports the hypothesis of transmission between these mammalian hosts. The findings raise concerns about the ecological impact of H5N1 outbreaks on marine mammal populations, as the virus has caused mass mortality events, particularly among breeding colonies of terns and seals.
