After 15 years of reporting on infectious disease outbreaks, what continues to fascinate me about them is the challenge of making high-stakes decisions under uncertainty.
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After 15 years of reporting on infectious disease outbreaks, what continues to fascinate me about them is the challenge of making high-stakes decisions under uncertainty. The hantavirus outbreak on the MV Hondius is a perfect example.
My story in Science is here (and a thread to come):
https://www.science.org/content/article/what-do-passengers-cruise-ship-hit-hantavirusTake a concrete and looming decision:
The MV Hondius left for Tenerife on Wednesday evening and should arrive this weekend. So what to do then with the people currently on board the ship? Should they be put in quarantine? Or can they just go home? On a commercial flight? How do you monitor them? -
Take a concrete and looming decision:
The MV Hondius left for Tenerife on Wednesday evening and should arrive this weekend. So what to do then with the people currently on board the ship? Should they be put in quarantine? Or can they just go home? On a commercial flight? How do you monitor them?One question, of course, is what the scientific evidence suggests about human to human spread of this virus.
And that's already where it gets complicated, so let's do it bit by bit: -
One question, of course, is what the scientific evidence suggests about human to human spread of this virus.
And that's already where it gets complicated, so let's do it bit by bit:Hantaviruses are generally not transmitted from human to human. Instead, humans catch the virus from rodents carrying the pathogen, usually by breathing in dust contaminated with their urine, saliva, or droppings—or by being bitten or scratched by the animals.
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Hantaviruses are generally not transmitted from human to human. Instead, humans catch the virus from rodents carrying the pathogen, usually by breathing in dust contaminated with their urine, saliva, or droppings—or by being bitten or scratched by the animals.
But when Andes virus was discovered in 1995, a different pattern quickly emerged. Take this 1996 outbreak:
The first patient was a 41-year old man in the town of El Bolson in the foothills of Patagonia. Three weeks after he first noticed symptoms, his 70-year old mother and then his doctor fell ill.
https://wwwnc.cdc.gov/eid/article/3/2/97-0210_article -
But when Andes virus was discovered in 1995, a different pattern quickly emerged. Take this 1996 outbreak:
The first patient was a 41-year old man in the town of El Bolson in the foothills of Patagonia. Three weeks after he first noticed symptoms, his 70-year old mother and then his doctor fell ill.
https://wwwnc.cdc.gov/eid/article/3/2/97-0210_articleBut what is really striking is what happened then:
Almost 4 weeks after the doctor’s first symptoms, his wife, herself a doctor, also fell ill. She travelled to a hospital in Buenos Aires, where a doctor spent an hour examining her.
24 days later, this doctor too became ill. -
But what is really striking is what happened then:
Almost 4 weeks after the doctor’s first symptoms, his wife, herself a doctor, also fell ill. She travelled to a hospital in Buenos Aires, where a doctor spent an hour examining her.
24 days later, this doctor too became ill.And then there’s the 2018/19 outbreak in Chubut Province. The researchers who investigated that outbreak write that it was touched off when the index case attended a birthday party for 90 minutes while feeling sick. Five guests at that party later fell sick themselves.
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And then there’s the 2018/19 outbreak in Chubut Province. The researchers who investigated that outbreak write that it was touched off when the index case attended a birthday party for 90 minutes while feeling sick. Five guests at that party later fell sick themselves.
Those guests then touched off further rounds of human-to-human transmission.
“On the basis of evidence from five reconstructed person-to-person transmission events, the route of infection in secondary cases was possibly through inhalation of droplets or aerosolized virions.”
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Those guests then touched off further rounds of human-to-human transmission.
“On the basis of evidence from five reconstructed person-to-person transmission events, the route of infection in secondary cases was possibly through inhalation of droplets or aerosolized virions.”Yes, there have been questions raised about the strength of the evidence of human-to-human transmission incl this review that says “despite claims of authors from Argentina and Chile of the existence of human-to-human transmission of ANDV, the balance of the evidence does not support this claim”.
https://academic.oup.com/jid/article/226/8/1362/6369311 -
Yes, there have been questions raised about the strength of the evidence of human-to-human transmission incl this review that says “despite claims of authors from Argentina and Chile of the existence of human-to-human transmission of ANDV, the balance of the evidence does not support this claim”.
https://academic.oup.com/jid/article/226/8/1362/6369311But, my personal take: I think there is plenty of evidence.
As virologist Gustavo Palacios told me it’s a question of where the bar is set. “Did I formally prove that this virus transmits from human to human? Well, probably I did not, but I think that based on most of the evidence you can conclude that.” -
But, my personal take: I think there is plenty of evidence.
As virologist Gustavo Palacios told me it’s a question of where the bar is set. “Did I formally prove that this virus transmits from human to human? Well, probably I did not, but I think that based on most of the evidence you can conclude that.”So that’s part of the scientific question answered to my satisfaction at least: There’s pretty good evidence of some human to human spread of this virus.
Now the question is: Okay, but how likely is that to happen and under what circumstances? And that’s where it gets even less certain. -
So that’s part of the scientific question answered to my satisfaction at least: There’s pretty good evidence of some human to human spread of this virus.
Now the question is: Okay, but how likely is that to happen and under what circumstances? And that’s where it gets even less certain.The most basic answer is that human to human transmission appears pretty rare.
Remember that in 30 years of history of this virus we only have a few good examples.
Human-to-human transmission also seems to usually require close contact. So think spouses, intimate partners. (Yes, there are exceptions. There always are.)
And patients were most likely to spread the virus just around the time they developed first symptoms, incl. just before. -
The most basic answer is that human to human transmission appears pretty rare.
Remember that in 30 years of history of this virus we only have a few good examples.
Human-to-human transmission also seems to usually require close contact. So think spouses, intimate partners. (Yes, there are exceptions. There always are.)
And patients were most likely to spread the virus just around the time they developed first symptoms, incl. just before.So that's the science before all this. Does the outbreak change any of that? Has the virus learnt to spread better?
No reason to think so.
1. Still not clear how much it actually spread on the ship.
2. A cruise ship is exactly where you'd expect a virus to spread that is not great at spreading. -
So that's the science before all this. Does the outbreak change any of that? Has the virus learnt to spread better?
No reason to think so.
1. Still not clear how much it actually spread on the ship.
2. A cruise ship is exactly where you'd expect a virus to spread that is not great at spreading.So take all of that uncertainty in terms of the scientific evidence and now mix in the media hype, politicians trying to score points, a public still reeling from the pandemic plus an incentive for organizations to err on the side of caution.
This is what makes this so fascinating to me. -
So take all of that uncertainty in terms of the scientific evidence and now mix in the media hype, politicians trying to score points, a public still reeling from the pandemic plus an incentive for organizations to err on the side of caution.
This is what makes this so fascinating to me.I think how this plays out the next few days will tell us something about the state of public health and the world. "This is a test of the emergency broadcasting system", epidemiologist Mike Osterholm told me. "This is not an international crisis, but it serves as a test of international crisis response"
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I think how this plays out the next few days will tell us something about the state of public health and the world. "This is a test of the emergency broadcasting system", epidemiologist Mike Osterholm told me. "This is not an international crisis, but it serves as a test of international crisis response"
I'll leave things here for now. Barely made it to the end of this thread because there is so much going on.
We'll leave the actual plans for passengers for another day/thread.
Do read the story (and share it):
https://www.science.org/content/article/what-do-passengers-cruise-ship-hit-hantavirus -
So that’s part of the scientific question answered to my satisfaction at least: There’s pretty good evidence of some human to human spread of this virus.
Now the question is: Okay, but how likely is that to happen and under what circumstances? And that’s where it gets even less certain.@kakape Likelyhood seems quite high: five people at a birthday party in a short time (90 minutes). But this was when the source case was symptomatic.
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I'll leave things here for now. Barely made it to the end of this thread because there is so much going on.
We'll leave the actual plans for passengers for another day/thread.
Do read the story (and share it):
https://www.science.org/content/article/what-do-passengers-cruise-ship-hit-hantavirus@kakape Kai, in your opinion, is there any chance this will turn into a global pandemic the scale of COVID? Assuming government responses are as bad as they were then.
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