In May of that year, Department of Conservation (Doc) kakapo science adviser Dr Andrew Digby raised the alarm, posting on Twitter that staff were working to understand what had caused a spate of the respiratory disease aspergillosis in kakapo chicks and adults.
At the time, four kakapo chicks and an adult bird had died in less than a month.
By the end of the aspergillosis outbreak on Codfish Island, 21 birds were infected, and the illness caused the deaths of two adult kakapo and seven chicks.
Genomics Aotearoa director Prof Peter Dearden said this week that after the first wave of aspergillosis, other birds were treated as though they had the disease without it being "completely confirmed".
It therefore remained unclear how much of the population was infected.
The disease was not fatal for all the birds that contracted it, but the only reason more birds did not die was the "massive amount of effort" by wildlife vets and other conservationists at the time, Prof Dearden said.
What scientists had now confirmed, but what remained highly unexpected, was that it was a single strain of the black mould aspergillus that was behind the crisis.
Exposure to aspergillus usually only affected people with weakened immune systems or other underlying issues.
Researchers had looked to identify the underlying cause but were unable to find anything — what they could find was "one strain" of aspergillus.
"If you were a human patient with aspergillus, you would probably have multiple strains through the environment, because basically your body is a good place to grow mould if your immune system doesn’t work.
"To find that these birds all have the same strain — it’s actually that strain that’s the problem," he said.
The black mould that might be growing on windows at a person’s home was genetically diverse.
"That’s the crucial thing. There seems to be there’s some source somewhere that we haven’t managed to completely nail down — that’s certainly carried by humans — that seems to have infected them all with this same strain of aspergillus.
"That is unexpected, and that’s why it took two years to get this paper out — we had to do a little work to convince the reviewers that this was even possible."
From the time of the outbreak, researchers used genomics to sample and test the whole island where the outbreak took place.
Everything from the dead kakapo to the nests and feeding areas, to boats, clothing, beaches, people and equipment were tested.
What stood out was the single strain of aspergillus.
The finding was so unusual that the journal the researchers submitted to initially rejected the study.
However, the uniqueness of the finding managed to attract interest from scientists, doctors, geneticists and immunologists from around the world who contributed their time and expertise to the study.
Researchers from universities in the United Kingdom, United States and Canada, as well as hospitals in the Netherlands and across New Zealand contributed, Prof Dearden said.
Dr Digby said the collaboration among researchers had been "amazing and inspirational".
As a result of their findings, Doc was doing things differently.
The department was more cautious about human contact, they were more hands off, and they did not foster chicks between nests as often to avoid spreading disease.
