The cruise ship hantavirus outbreak offered a real-life simulation exercise. Did we pass?

A lifelessly irruption on a sail ship. Passengers from dozens of countries around the domain. A worldwide effort to bring people home safe — including multiple Canadians — as more infections kept appearing.

The reality of the last few weeks has been unsettling enough. But what if it hadn’t been hantavirus?

What if the rare animal-transmitted infection that found its way onboard a cruise had been something more insidious, more contagious, more surprising?

Let's hope we won't learn the answers to those what-ifs any time soon. But what we do know is warning enough.

Before global health officials had any idea that a rodent-borne illness was silently spreading on a weeks-long Atlantic cruise, a Dutch passenger died on board. His wife — while unknowingly carrying the virus — disembarked at the remote island of Saint Helena, flew to South Africa, and later collapsed in the Johannesburg airport and died in hospital.

A British man with signs of pneumonia was evacuated for medical care. A third passenger, from Germany, who was still on the ship, later died as well.

Dozens more left the MV Hondius mid-cruise, travelled home, and went about their lives. They flew on planes and waited in busy airports. They may have come into contact with untold numbers of other people, including here in Canada.

All over a period of several weeks.

All while more passengers on board started showing symptoms.

All before any test for hantavirus actually came back positive.

In recent days, new cases began appearing off the ship as well. Since the Dutch-flagged Hondius docked in the Canary Islands over the weekend, as part of a coordinated World Health Organization (WHO) effort to get roughly 46 passengers and crew safely back home, several more individuals have fallen ill.

In the U.S., one passenger showed mild symptoms during transport to an isolation facility, while another tested positive, health officials there said on Sunday night. A French national on a chartered flight back to Paris also developed symptoms, French officials announced the same day. 

Meanwhile a symptomatic passenger from Switzerland is being treated at a hospital in Zurich, and there's an additional suspected case on the remote island of Tristan da Cunha, where the ship stopped in mid-April.

That's a dozen confirmed or suspected infections and counting. And it's hard to fathom the amount of contact tracing needed to hunt down other possible cases.

Canadians from hantavirus-hit ship isolating, currently have no symptoms: B.C. Health officer

This outbreak has now been unfolding for nearly six weeks, and the virus itself can incubate inside someone's body for a month or more before any symptoms show up. Even more challenging: the crisis involves nearly 150 people from 23 different countries, possibly more. 

And though scientists suspect patient zero caught the virus during a birdwatching excursion on land, there is still no official explanation for how a rare pathogen found its way onto a cruise ship.

Enough mistakes, missteps, or bad luck, and it could have led to a worse scenario, given the uncertainties and complexities involved — especially if this was a different threat.

This particular pathogen, the Andes strain of hantavirus that's proven capable of causing sporadic human-to-human outbreaks, is not expected to spark another pandemic.

It is deadly, there is no question, but it isn't brand new, rapidly evolving or unusually contagious. Most people catch it directly from rodents, not each other. WHO officials are unequivocal about that. 

"This is not COVID, this is not influenza," said Maria Van Kerkhove, director of epidemic and pandemic management, during a Thursday briefing. "It spreads very, very differently."

"The circumstances here were just an unfortunate and rare series of events," the Stanford University researcher said.

Why aren't all hantavirus quarantines the same length?

Dr. Isaac Bogoch, an infectious disease specialist in Toronto, also said he would be "shocked" if there weren't more infections in the days, or even weeks, ahead.

"If everyone does their role, people will be identified, they can be isolated safely, they can receive appropriate medical care, and this outbreak can be quelled," he said. "But that's a big if."

That "big if" will play out for weeks to come. And what if this had been, say, an evolving strain of bird flu, or some other pathogen finally making an explosive jump from animals into humans? 

Well, the ship would've already sailed, so to speak. 

"There's going to be an increasing frequency of spillover events to humans, and then, of course, potential for subsequent human-to-human transmission and outbreaks like this," Bogoch said. "We have to be prepared for rapid international coordination."

If this hantavirus outbreak offers a trial run for a worst-case scenario — a real-life simulation exercise of sorts — it's evident there is no universal playbook for what containment efforts should look like during such an unusual outbreak.

How long, exactly, should possible contacts be isolated from others? Should people without symptoms get tested, or only those showing signs of active disease?

The WHO recommended a "cautionary approach," involving daily monitoring and either home- or facility-based quarantine for 42 days.

Some countries asked individuals from the ship to self-isolate at home for around six weeks, while in Spain, nationals flown into Madrid are undergoing mandatory quarantine in a military hospital.

Certain countries, such as the U.S. And U.K., appear to be testing at least some returning passengers, regardless of symptoms; others, including Canada, have not.

Canada's isolation approach also varies, since passengers have flown back to different provinces at different times. Some returned on their own after leaving mid-cruise and are isolating at home in Ontario and Quebec.

Others are being encouraged to stay at their homes in Alberta and Ontario after possible exposure to a hantavirus case on a flight. Four more travellers were brought back to B.C. After being stuck on the ship for several weeks.

In B.C., where passengers are being sent to pre-arranged lodgings for at least three weeks, an isolation period which could be extended up to the WHO's recommendation of 42 days, if necessary. 

Speaking candidly to the media on Monday, B.C.'s provincial health officer, Dr. Bonnie Henry, said all four people are symptom-free so far, but suggested there have been shifting decisions behind the scenes over how best to handle them.

In terms of isolation time frames, when does the clock start? Henry said there were discussions around whether to backdate the start of isolation to May 6, but it was later decided to start the isolation period upon the passengers' arrival in B.C.

Discussions are also underway in Canada about when to test for hantavirus, Henry added, since there is still "very little known" about when tests are helpful.

Those varying efforts — province by province, country by country — may remain somewhat uncertain, but should be enough to stamp out this cluster of hantavirus cases and protect the broader public. 

Even so, the Hondius crisis offers a cautionary tale for what can happen when a virus moves faster than any global efforts to contain it.

A different pathogen, a different setting, a different streak of bad luck? It could have been worse.

Senior Health & Medical Reporter

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