When the 1918 flu reached Samoa from New Zealand it incapacitated 90 percent of adults, killed about a quarter of the population, and tarnished the relationship between the two countries, medical historian Ryan McLane says.
The SS Talune left Auckland harbour with a clean "bill of health" 100 years ago, despite the captain knowing there were sick people on the ship even as the second wave of the deadly 'Spanish flu' epidemic ravaging the city.
The ship travelled around the Pacific Islands, leaving flu in its wake.
Clinician and historian Ryan McLane, who is a communicable diseases specialist and a health advisor at the Ministry of Foreign Affairs and Trade, says Samoa was the worst-hit country in the world.
He explains to Afternoons' Jesse Mulligan why the tragedy happened the way it did, and how it tarnished the relationship between the country and New Zealand.
"Fiji, somewhere between five and seven percent of the population died, Tonga between five and nine percent - and Western Samoa to the best of our knowledge was hit worse that anywhere else on the planet.
"Roughly a quarter of the local population died in eight weeks."
More about the 1918 flu and its effects in Samoa:
McLane says the characteristics of the 1918 strain of flu made things worse for Samoa.
"The 1918 influenza was strange in many ways - it struck in the middle of summer, it was the second wave in the same year…"
"More than anything else, influenza normally kills infants and the very old … this particular variant of the 1918 exclusively or nearly exclusively killed 18-45 or 50 year olds, which were the people most active in society.
"So when I say that a quarter of the population of Samoa died, we're talking about more than half of the young adults dying in the space of eight weeks.
"It actually broke the country for a short period - 90 percent of the adults were simultaneously bedridden and were not able to do anything … when they recovered, the majority of their leadership had died.
"The traditional leadership, the church leadership, the teachers, the trading factors - these individuals in many cases they lost 60 to 70 percent of those people or more of those people to the flu."
He says the story of the flu in Samoa is really the story of the SS Talune.
"The Talune had a set voyage where they went to Fiji and western Polynesia mostly to pick up perishable goods like fruit.
"They'd stop in Fiji, pick up workers, travel on to Samoa, Tonga, back to Fiji to drop off the workers and then back to New Zealand … they did this most months.
He says the ship was given a clean bill of health when it left Auckland.
"People think that the bill of health means that the ship wasn't infected, that's not true: the bill of health is signed at the last port it was in, stating that there were no infectious diseases active in that port.
He says the clean bill of health was more intended to stop the spread of other infectious diseases - smallpox, cholera and plague being the big three.
"We didn't know anything about viruses … the majority of doctors then seemed to have believed that influenza was caused by 'miasma' which is a gas that either came from rotting organic debris or just out of the ground.
"They didn't recognise it as infectious - they were starting to understand that but at the time as I said probably the majority would not have agreed that it was infectious.
"In mid-October, Auckland was absolutely racked with the second wave of the 1918 influenza, however it had not been declared a reportable disease for public health purposes yet.
"There was no way to stop ships leaving the harbour, or no reason seen to have ships stopped."
He says it was also made worse by Armistice Day celebrations.
"This struck in New Zealand and then in the Pacific right at the end of the First World War, which means that exactly at the time governments were trying to put in place quarantines or control the spread of this disease you had your armistice day celebrations which across the Pacific were some of the largest parties ever seen in those countries.
"In Suva they state that that [Armistice Day] was the largest event they'd ever seen and people came in from all over the country, so it became this perfect way to transmit influenza again to anybody that might not have caught it the first time it appeared."
However, it was the stark difference between Western and American Samoa that caused the rift with New Zealand.
"For a number of reasons, American Samoa 50km away had absolutely no one die from the influenza," McLane says.
"The Western Samoans, which had been occupied by New Zealand only 4 years before, taken from the Germans, looked across and said 'why did this happen to us, what was it that allowed this into our country when in American Samoa the disease never penetrated?'.
"That was one of the things that helped inspire the Mau - which was the rebellion or long-term protest movement against New Zealand occupation of Western Samoa."
The division between New Zealand and the Mau led to the Black Saturday incident in 1929 when a march to welcome home two members who had been exiled in New Zealand erupted into a fracas that prompted police to fire on the crowd, leaving at least eight people dead.
However, McLane says even had the SS Talune never gone to the Pacific Islands, another vessel likely would have.
"The Niagara, which some people blame for infecting New Zealand, stopped in Fiji before New Zealand, and there were a number of other ships."
He says it's possible that may have had a different outcome, however.
"In Australia, where they had quite an effective quarantine, it kept it out just for a matter of months but that was long enough to have the virus actually degrade quite a bit in mortality - it was much less dangerous when it penetrated Australia than when it came to New Zealand.
"So, they may have had a much better outcome [in Samoa] simply by keeping the virus out for another few months, but I think they eventually would have become infected."