Using the genetic contents of toilet flushings to monitor the prevalence of viruses was a striking Covid-era achievement. Similar techniques may help detect the arrival of highly pathogenic bird flu, which recently landed on our icy southern doorstep.
It’s hoped an avian equivalent of Covid wastewater testing will emerge from a new project funded by Te Niwha, an infectious diseases research platform formed in Covid’s wake. Professor Jemma Geoghegan, an evolutionary virologist at the University of Otago, co-leads the project. “We want to include environmental detection because it’s sometimes too difficult to get samples directly from birds,” she says. Environmental samples that could contain the flu’s tell-tale RNA sequence might include water or droppings.
The team will initially study existing viruses as a proxy for the lethal bird flu. “First, we need to know if we can use environmental samples to detect viruses we already have,” she says. “There are low pathogenic strains of avian influenza virus that have always been in aquatic birds.” By taking samples in New Zealand and the sub-Antarctic islands, the team also aim to learn how mild strains spread.
In February, two flu-infected skua corpses were found on mainland Antarctica opposite Tierra del Fuego, the closest cases to New Zealand yet. That’s the current frontline of the highly pathogenic H5N1 virus strain that was discovered in Europe in 2020 and spread by migratory birds around the globe. Oceania is the only region to so far escape, says Nigel French, distinguished professor of infectious disease epidemiology and public health at Massey University.
He says the strain is causing great concern, as many millions of birds have died. It is also affecting mammals, including marine mammals and fur-farmed carnivores. “That’s a concern, because humans are mammals. At the moment, person-to-person transmission is very low risk. But if it evolves to become transmissible between mammals, that would have serious consequences. It has a 60% mortality rate in humans.”
The Antarctic’s dense bird populations, which facilitate disease spread, are breaking up for winter. Bruce McKinlay, a Department of Conservation (DOC) technical adviser on ecology, believes this could slow the disease’s march around the region.
We can only speculate how it might spread to here from Antarctica or elsewhere, he says. “It could even come down to vagrant birds that do pop up here unexpectedly. It only takes one.” However the disease arrives here, McKinlay suspects waterfowl would spread it rapidly. “The shoveller duck moves across the whole country in seven days. The natural gut flora of waterfowl carry a lot of flu virus, giving them a basic ability to live with avian influenza. That dispersal will probably limit our ability to manage the disease in wild birds.”
A vaccine for the deadly flu is registered overseas for poultry, although many countries don’t vaccinate (the Poultry Industry Association of NZ hasn’t decided whether it will). DOC is trialling it on black stilt/kakī, shore plover/tūturuatu, red-crowned kākāriki and kākāpō, all of which are captive or intensively managed.
“It’s a safety and efficacy trial to look at the level of antibodies they gain,” says McKinlay. But vaccinating wild birds, even taonga and threatened species, will be futile, he says, because they’re so mobile. “No one should be expecting wide-scale vaccination in wild birds.” He is somewhat reassured the disease isn’t reported to have caused extinctions overseas, but notes survival is already precarious for many of our native species.
Bird flu causes neurological disease, and McKinlay wants people to report any any signs of it to the Ministry for Primary Industries hotline. Infected birds may tremble, fall over or have crooked necks. Take photos, he says, but stay away and don’t touch. “We don’t want birds being moved around by caring people.”
