The bird flu is a poultry disease caused by certain types of viruses that normally infect birds. This disease is caused by several influenza A viruses.
An international scientific team with researchers from the CSIC that investigates the presence and impact of highly pathogenic bird flu come in here Antarctic fauna has established that the virus has spread to the northern Antarctic region of the Weddell Sea and that could pose a threat to the conservation of nature wild fauna.
CSIC researchers led by the virologist Antonio Alcamí, from the Severo Ochoa Molecular Biology Center (CSIC-UAM), with the coordination of the Spanish Polar Committee and the support of the Spanish Research Agency, all three dependent on the Ministry of Science, Innovation and Universities have installed a molecular diagnostic laboratory at Spain’s Gabriel de Castilla Antarctic base and confirmed on February 24 the presence of the highly pathogenic bird flu virus (HPAI) H5N1 in remains of dead skuas, a species of bird related to seagulls, found at Argentina’s Primavera Antarctic base.
Following the discovery, an international expedition was launched on March 13 on board the Australis sailboat (HPAI Australis Expedition) with the participation of CSIC researchers Begoña Aguado and Antonio Alcamí to to monitor the presence of the virus in the region of the Antarctic Peninsula and the northern Weddell Sea.
The team found that hunters are the hardest-hit species to date, and that the high mortality rates show that this could have long-term implications for their conservation at a regional level.
The evolution of highly pathogenic bird flu
The HPAI H5N1 virus initially developed in poultry, but has recently adapted to spread better among poultry wild fauna. Since 2020, its unprecedented spread has resulted significant mortality among wild birds and mammals almost everywhere in the world. After arriving in South America in late 2022, the arrival in Antarctica was planned for subsequent years and was finally confirmed in February 2024.
The country’s arrival on the southern continent has raised concerns consequences for Antarctica’s wildlife populations, as many species are already classified as endangered or critically endangered. Moreover, the high mortality is under wild faunaas has been observed on other continents such as South America, could go unnoticed here due to the distance from the Antarctic continent and limited access to regular monitoring.
“Therefore, implementing surveillance tools that are feasible in an Antarctic context could help monitor the impact of the HPAI virus in the coming years,” said Meagan Dewar, expedition leader.
Multidisciplinary team to study the extent of highly pathogenic bird flu
“The close collaboration of an interdisciplinary scientific team, consisting of biologists, veterinarians, virologists and an experienced crew in the Antarctic region, was decisive for the success of the expedition,” says CSIC researcher Antonio Alcamí. This team is trained to move from mere suspicion to taking samples and analyzing them. The expedition went to investigate the region of the PAntarctica and the northern Weddell Seaa region where surveillance efforts by the National Antarctic Programs have been limited, but where the Scientific Committee for Antarctic Research (SCAR)-Antarctic Wildlife Health Network (AWHN) has received reports from researchers, ornithologists and the general public of life-threatening events or diseases among wild fauna.
Once on site, the team conducted a preliminary examination of sick individuals or unusual mortality among faunaand then collected samples to analyze the virus. In addition to collecting non-invasive samples from sick individuals, hundreds of fecal samples were also taken from apparently healthy animals to investigate the prevalence of the virus in them. Similarly, air and water samples were also collected which will help determine the presence of the virus in the vicinity of the area.
On board a molecular diagnostic laboratory
On board the ship, CSIC researchers installed a diagnostic laboratory. “Having a specialized laboratory on board the sailboat was crucial for the expedition, as it allowed the team to use advanced methods to quickly detect the HPAI virus and sequence its genome,” says Begoña Aguado. This onboard analysis, which has not been performed to date, represents a notable logistical advance for HPAI virus surveillance in the Antarctic region, as confirmation is rapid and does not rely on sending samples to distant analysis facilities.
During the expedition, the team explored ten wildlife-rich areas between the South Shetland Islands, the Northern Weddell Sea and the Danger Islands. The presence of the HPAI virus was confirmed by multiple laboratory tests, including PCR specific for influenza virus and the H5 subtype, followed by sequencing of the protease cleavage region, which defines with 100% certainty the presence of the HPAI virus. The virus was identified in hunter remains at four landing points (Hope Bay, Devil Island, Paulet Island, and Beak Island) and was detected in numerous specimen types, including the brain, suggesting neurotropism of HPAI virus infection in this species.
Of the locations visited, Beak Island stands out because it is home to a large colony of hunters. While 80 living hunters were counted during the visit, more than 50 were found dead. Of these 50, 10 were analyzed and all tested positive.
On another island of the same archipelago (Isla Heroína), where a large colony of Adelie penguins lives, there is also a mass death of these animals with more than 500 bodies at the surveyed site, indicating that an abnormal mortality event may have occurred involving multiple thousands of penguins would have died. Although the team suspects that the event may have been caused by the HPAI virus, the presence of the virus has not been confirmed by PCR and other tests will be developed in the coming months to determine the cause of the deaths.
Testing healthy fauna
The institutes that are part of the expedition will also analyze samples using multiple techniques wild fauna apparently healthy, as well as an extra set of corpse samples. These upcoming analyzes will provide more information about the presence of the virus in apparently healthy animals and about the genetics of the viruses detected. This data will help understand how the virus has spread over time and space. In addition, tissues from infected cadavers will be analyzed to understand how the virus causes disease and death, and to help understand which tissues are best suited to detect the virus.