Credit FAO/WOAH
#17,634
Although H5N1 was only first detected in South America 10 months ago, it has already spread 6,000 miles down the continent - killing hundreds of thousands of birds, and tens of thousands of marine mammals in the process - and is now threatening to jump to Antarctica.
As it travels, it encounters new hosts, and local avian/swine/human flu viruses, which can contribute to its continued evolution. Already, numerous new genotypes have been identified. Last March, in Preprint: Highly Pathogenic Avian Influenza A (H5N1) in Marine Mammals and Seabirds in Peru, its authors wrote:
These viruses are rapidly accruing mutations as they spread south. Peruvian viruses do not contain PB2 E627K or D701N mutations linked to mammalian host adaptation and enhanced transmission, but at least 8 novel polymorphic sites warrant further examination.
Yesterday the FAO/WOAH OFFLU Network published a 14-page statement on the impacts, and challenges, facing South America since the arrival of HPAI H5N1. Due to its length I've only reproduced the abstract.
Follow the link to read it in its entirety. I'll have a brief postscript after the break.
23 August 2023
OFFLU ad-hoc group on HPAI H5 in wildlife of South America and Antarctica
Abstract
This report summarizes the spread of high pathogenicity avian influenza of the subtype H5 (HPAI H5) clade 2.3.4.4b in South America since it was first detected in the region in October 2022, and evaluates the risk for incursion into Antarctica in the near future. The focus of the report is on HPAI H5 in wildlife, and not spread in poultry or rare spillover to humans, as these are the subject of other reports. We do recognize and fully support a One Health approach to HPAI H5: an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals (both wild and domestic) and ecosystems.
Since HPAI H5 was first reported in Colombia in October 2022 (WAHIS, 2022a), it has spread across South America with devastating consequences for its wild bird and mammal populations (GamarraToledo et al, 2023b; Leguia et al, 2023). In Peru and Chile, more than 500,000 wild birds of at least 65 species and more than 20,000 wild mammals of at least 15 species were reported dead, with actual mortality likely many times larger. This mortality is a potential threat to the conservation of several wild animal species.
For example, HPAI-H5-associated losses included about 36% of the endangered Peruvian pelican (Pelecanus thagus) population in Peru, about 13% of the vulnerable Humboldt penguin (Spheniscus humboldti) population in Chile, and about 9% of the South American sea lion (Otaria flavescens) population in Peru and Chile.
After its first detection in South America, HPAI H5 virus has spread rapidly to the southern tip of South America (south of 40°S latitude), a distance of more than 6000 km in just three months. The recently reported detection of this virus in a South American sea lion at Puerto Williams, Chile (54.9S), is the southernmost detection of the virus to date.
There is a substantial risk it will continue southwards and in the near future reach Antarctica and its offshore islands, which are home to more than 100 million breeding birds, 6 species of pinnipeds and 17 species of cetaceans. This risk may be increased in coming months due to the spring migration of wild birds from South America to breeding sites in the Antarctic.
The negative impact of HPAI H5 on Antarctic wild birds and mammal populations could be immense, both because of their likely susceptibility to mortality from this virus, and their occurrence in dense colonies of up to thousands of pinnipeds and hundreds of thousands of birds, allowing efficient virus transmission.
Although little can be done to stop HPAI H5 from spreading to Antarctica and causing mortality in Antarctic wild birds and mammals, there are several detection and response options possible. These include surveillance and accurate documentation of HPAI-H5-associated mortality events, and following guidelines to reduce risk of human-mediated virus spread.
In the Northern hemisphere, migratory birds spend their summers in their high latitude breeding areas in Alaska, Canada, Siberia, and the Arctic. There they may share avian viruses picked up on their trek north, which may then be dispersed along their migratory routes in the fall (see Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1).
Should HPAI H5 establish a foothold in the Antarctic, we could find ourselves dealing with yet another annual source for unpredictable reassorted avian flu viruses.
As this statement points out, there is little we can do to prevent it from happening, but there are some steps (like removing infected carcasses from the wild) which may slow its progress. Just as importantly, we need to improve our surveillance and reporting from the region.
So that if something more challenging does emerge - we'll know about it as early as possible.
