WHO is “hugely concerned” but is Australia at risk?

Scientists have reported horrifying scenes of South American beaches littered with the bodies of 17,400 baby elephant seals. The virus has killed polar and grizzly bears, decimated Peruvian pelican populations and infected bottlenose dolphins, lions and skunks.

The virus has devastated the world’s largest colony of northern gannets in the UK, killing 70 per cent of the population and turning the eyes of survivors from blue-white to black. Scientists don’t know why.

And, for the first time, bird flu has spread to Antarctica, where it could have a catastrophic effect on penguins and seals.

“These viruses seem to be jumping to mammals and coming back to birds, which is something we really haven’t seen before,” Ward said. “The more often this happens, the more likely it is that at some point these viruses will begin to acquire undesirable characteristics that would then allow them to be transmitted from human to human. The example of cattle in the United States goes that way.”

First cow infection leads to latest human case

Charging

On March 25, U.S. officials announced that the virus had infected a herd of dairy cows in Texas, the first cases of bird flu in cattle. A month later, at least 34 herds in nine states were sick with the flu.

A new genomic analysis shows that the strain has been circulating undetected in cows since early January and may have gained at least one adaptation related to viral spread in mammals.

In the midst of the cow outbreak, a dairy farm worker fell ill with the virus which, unusually, manifested as conjunctivitis. The strain could not be transmitted to another person and the man recovered.

But the incident led WHO chief scientist Dr Jeremy Farrar to say he had enormous concern about a scenario in which the virus “evolves and develops the ability to infect humans and then, critically, the ability to pass from one human being to another.”

Infection in pigs could be particularly dangerous because they are “mixing vessels” that can contract human and bird flu strains, Ward said.

In a co-infected pig, “one virus could distinguish characteristics from the other,” Ward said. “That kind of situation can create one of these super viruses that has the ability to transmit much more easily.”

Why is Australia still virus-free?

Despite the concern, humans remain a “dead-end” host for bird flu. The virus has never achieved sustained human-to-human transmission and remains an adapted disease in birds, said Dr. Frank Wong, a bird flu expert for WHO at CSIRO’s Australian Center for Disease Preparedness.

“There is still no conclusive evidence that cattle are transmitting each other through respiratory infection,” Wong said. “When cattle are sampled, the viral load is mainly found in the mammary glands, udders and milk, and not in the respiratory tract of the cows.”

The virus may have spread among cows through unsterilized milking equipment or feed, rather than through the air like COVID-19, limiting its potential to take off as a human pandemic.

Australia remains a holdout for the disease, Wong said, due to strict biosecurity laws and the fact that the continent is not a major stopover for migratory duck and geese species that carry the virus. But a Department of Agriculture, Fisheries and Forestry report recently raised the risk of highly pathogenic bird flu reaching Australia to high. The report says migratory shorebirds, shearwaters and nomadic waterfowl are species that could bring the virus to Australia.

Charging

The first sign of the disease here, Wong said, would likely come from a mass die-off of wild birds or a suddenly sick flock of backyard chickens. Detection of the virus in poultry would trigger a rapid “culling” measure, or culling of affected flocks, which is how authorities eliminated eight previous outbreaks of the disease.

DAFF investigates mass bird die-offs and also carries out general surveillance of wild bird feces for the presence of the virus. Wong’s lab checks whether positive samples are from the exotic, problematic variant or the low-pathogenic strain that circulates naturally.

The clade behind the latest global outbreak has never been detected in Australia.

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