Millions of poultry birds across different regions of the world have been infected in recent months by a strain of avian influenza virus, which is both lethal and highly infectious. Now, scientists are troubled about these bird flu outbreaks.
What researchers have found to be more concerning is the spread of this deadly virus strain in wild birds, according to a paper in Nature. The bug appears to be spreading more easily in the wild than ever. This can make outbreaks more difficult to contain, as wild birds can carry them globally through their migrations.
Outbreaks put vulnerable species at great risk and could impact humans as well.
About the virus
Researchers say the H5N1 virus strain has been responsible for almost 3,000 outbreaks in poultry populations across countries since October. These led to the culling of an estimated 77 million birds to check further spread.
In addition, non-poultry birds (including wild birds) numbering around 400,000 died in about 2,600 outbreaks.
The H5N1 strain was first seen in commercial geese about the year 1996 in Asia. By the early part of the 2000s, it had spread to poultry in Europe and Africa.
The highly infectious virus started causing mass deaths among wild bird populations by the year 2005, starting in East Asia and then spreading to Europe. There have been recurring outbreaks of the strain in wild birds since that time in many countries around the world.
According to scientists, it now appears the virus has adapted more to wild birds as a result of frequent spillovers. It has “now become an emerging wildlife disease,” said wildlife geneticist Andy Ramey.
A new H5N1 clade 184.108.40.206 virus emerged in 2014. This highly pathogenic H5 lineage did not kill all the wild birds that were infected with it, thus enabling the virus to spread to North America. Scientists say the 220.127.116.11 viruses are at the center of most outbreaks since their emergence, including the present ones.
One disturbing thing is that infections among wild birds are under-reported. Just a small part of cases are diagnosed, Ramey said. Improved monitoring is needed to get a better picture of the number of wild birds that have and die from it.
Possible threat to humans
Human beings can catch the virus, but infections are not very common. There have been only two reported cases since October – one in the U.S. and one in the U.K.
Scientists fear, however, that rising infections in wild birds could pose a threat to people. This may create more avenues for spillovers into humans. And such spillovers are thought to have been responsible for an increased adaptation of the virus in wild birds.
Where these infected birds choose to head to in the course of their migration determines where the next outbreaks would occur. Researchers think large outbreaks may continue in parts of Asia and Europe because of this. Infections could soon be seen in regions of the world that are not affected at present.
Bird flu viruses mutate slowly over time. But they can become more transmissible in humans and other species with the right mutation, according to Ian Barr of Melbourne’s Doherty Institute. The bugs have been likened to “ticking time bombs.”
Experts say there is an urgent need for improved infection monitoring among wild birds to reduce future outbreak risks. Targeted surveillance of areas with a high likelihood of holding the virus could still make some difference where resources are limited.
Reducing bird populations in production facilities would also help to curb the spread, according to experts. The development of a potent vaccine for poultry will aid in combating the outbreaks as well.