Why has the deadly bird flu has not reached Australia so far?

Why has the deadly bird flu has not reached Australia so far?

Australia and the rest of Oceaniens are the last regions that are free of the highly pathogenic tribe of the bird flu, which worldwide to Massive deaths in birds and led a big outbreak at Dilk cattle caused in the United States. Why the animals in this southern region have been spared an infection so far remains a mystery, but scientists have several theories.

Frank Wong, virologist at the Csiro Australian Center for Disease Preparedness in Geelong, explains that Australia is geographically isolated and has no living poultry imports. Many bird species of the country are endemic and do not hike in regions in which the virus is spread.

Michelle Wille, virologist at the Center for Pathogen Genomics at the University of Melbourne, emphasizes that the arrival of the virus in Australia is "a question of when, not the OB".

bird examination

Wille believes that long-distance migrants such as coastal birds and seabirds that move from Siberia and Alaska to Australia via Southeast Asia are most likely to bring the virus into the country.

This week Australian scientists started, including will, to test the first of almost 1,000 migratory birds on the virus. In the coming weeks, the Wedge-Sailed Shearwaters team (Ardenna Pacifica) and Short-Sailed Shearwaters (Ardenna Tenuirostris) will capture them from northern autumn to southern spring. At night, the scissors sleepers sleep in earth holes and are relatively easy to catch. The researchers will remove the birds on the virus and remove blood to test for antibodies that show an earlier exposure. They will test in particular on the H5N1-Clade 2.3.4.4b, which caused massive bird death and diseases in some mammals.

The researchers will travel to seven locations in all of Australia, which range from Broome in the northwest to Lord Howe Island in the east and Phillip Island in the south.

fatal ducks?

Will indicate that another possible transmission path of the virus via duck . Scientists believe that migrating ducks and geese in other parts of the world can spread the disease without developing it themselves.

This is because the epithelial cells of the ducks have a sensor, known as Rig-I, who recognizes an impact influenza virus and triggers an immune response that usually ensures that it is warded off. Kirsty Short, virologist at the University of Queensland in Brisbane, explains that ducks may have developed such defense mechanisms through repeated infections with fewer pathogenic virus forms in Asia, which gives them existing immunity. Although they do not become sick from H5N1, they can still transmit the virus and ducks gather in lakes and ponds with other birds, which increases the likelihood of disease distribution.

isolated ecosystems

Another reason why Oceania is currently free of the virus is that the duck species of the region are endemic and do not tend to migrate abroad.

This isolation is partially explained by a biogeographic border, which is known as the Wallace line and was first described in 1859 by natural scientist Alfred Russel Wallace. This line runs through Indonesia. Many animal species tend to stay on one side of the line or the other, and due to this isolation, the animals are different on each side. Michael Andersen, evolutionary biologist at the University of New Mexico in Albuquerque, describes this phenomenon as "a big secret" of the world.

The sharp dividing line could also mean that the virus is not adapted to animals east of the Wallace line, explains Wong. "Bird flu viruses, including this highly pathogenic bird flu virus, are particularly well adapted to certain species," he says. Birds in Australia could have a genetic profile that deals with the ordinary path of infection of the virus, but so far nobody has tested this hypothesis.

Although many duck types are short-distance migrants and tend to not exceed the Wallace line, there are a few species-including the Pacific black duck (Anas Superciliosa) and the pipelated pipe dent (dendrocygna guttata)-that do this, and will believe that they could introduce H5N1 into the region.

If the virus is detected, veterinarians will intervene immediately to euthanases the affected population, which has already happened, as H7N3 and H7N9 strains of the flu in Victoria in May.

Short says that the effects on Australia's birds, mammals and ecosystems are unclear when it comes to this, but probably many species are susceptible. "It's a big research gap," she adds.