Scientists from the British Antarctic Survey (BAS) have confirmed the detection of an outbreak of highly pathogenic avian influenza (HPAI, caused by the H5N1 virus) in populations of subantarctic skuas (Catharacta antarctica - Stercorarius antarcticus) in the Bird Island, in the South Georgia (South Sandwich) Islands, which represent the first known cases of this disease in the Antarctic region.
Following reports of several potentially symptomatic birds and unexplained mortality, BAS staff on Bird Island took samples for analysis. The collected swabs were sent to the United Kingdom and analyzed by the Animal and Plant Health Agency laboratories in Weybridge, where the presence of the H5N1 virus was confirmed, a pathogen that is causing serious mortality episodes (mainly in birds but also in mammals). and other groups of animals) in various areas of the planet.
Natural routes (infection between wild birds) are the main means of spread of HPAI and it is likely that the spread of the disease was caused by the return of birds from their migration to South America, where there is a large number of HPAI cases. BAS and the Government of South Georgia - South Sandwich Islands "remain alert to new cases and scientific and visitor programs currently continue under enhanced biosecurity measures," according to a note released by BAS itself.
The government of Georgia Island-Sandwich Island published on Monday, October 23, a first information note on the appearance of these cases of avian flu and the measures adopted.
The BAS has two research stations in South Georgia, including one on Bird Island, where confirmed cases with the presence of H5N1 were identified. After knowing the results of the analyzes, most of the field work related to animal handling was suspended, the BAS has indicated. Additionally, biosecurity measures have been intensified, including enhanced cleaning of clothing and field equipment, as well as observation of high-density wildlife areas.
The appearance of this first outbreak of avian flu in the Antarctic region, although the Georgia Islands are 2,000 km from the Antarctic continent, raises scientific concern about possible effects on many other species of birds, especially penguins.
"Key elements of the broader scientific program at Bird Island remain under caution, including long-term monitoring of marine predators such as wandering, black-browed and grey-headed albatrosses, northern and southern giant petrels, macaroni penguins and and gentoo penguins," indicates this official scientific body of the United Kingdom.
"It is not possible to forecast the impacts of HPAI in South Georgia, as transmission and mortality patterns in Europe and America have been highly variable. Local government and BAS "will continue to work together to monitor the impact of wildlife on Bird Island and the possible spread to other areas," details the official note.
Avian influenza is a viral disease that mainly affects birds. Low pathogenic avian influenza viruses are common in wild birds and often do not cause signs of illness. However, some strains of the virus, including H5 and H7, are highly pathogenic in domestic poultry and can cause high mortality if they escape into wild bird populations. These are known as highly pathogenic avian influenza (HPAI), reminds the BAS.
The current HPAI H5N1 outbreak began in 2022 and has led to the deaths of large numbers of seabirds in the Northern Hemisphere, southern Africa and around the Atlantic and Pacific oceans and throughout South America. While it remains predominantly a virus that affects birds, some mammals have been infected during the current outbreak. This is often due to predators and scavengers consuming infected birds or carcasses, but cases have also been observed in some marine mammals where this mode of transmission would not apply.
Although it is primarily a virus that is transmitted between birds, the World Health Organization (WHO) has noted that, while the number of cases in humans is extremely rare, the increasing number of detections of the current H5N1 strain among mammals raises concern. that the virus can adapt. infect humans more easily.
The main means of spread of HPAI is through natural routes and the confirmed presence of the disease on the South American continent made it very likely that it would reach South Georgia in the 2023-24 season. In preparation, the Government of South Georgia and the South Sandwich Islands (GSGSSI) updated its guidance on the risk and response to HPAI in the Territory. These included enhanced biosafety procedures and mitigation measures to be implemented for different groups/activities depending on the HPAI risk at each scientific or visitor landing site.
While the source of the disease on Bird Island is not certain, it is likely that it was introduced through sub-Antarctic skuas returning from their migration in Argentina, where there are known to be a large number of cases.
"The presence of HPAI could have serious implications for the abundant seabird colonies in the Antarctic region and the local government and the BAS are working in partnership to monitor current impacts," indicates the scientific entity.
