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Saturday, October 25, 2014

What would Thucydides do? How to create negative atmospheric pressure in the Ebola hot-zone

(Crossposted at Watts Up With That)
To keep pathogens from escaping, contagious disease laboratories and isolation rooms use negative atmospheric pressure (or negative relative air pressure) that pulls air in through all doors and cracks. Barriers are not enough. At the inevitable openings in the barriers, the movement of the pathogen must be inward, not outward. The same logic applies to the Ebola hot-zone countries of West Africa. Barriers in the form of travel restrictions and quarantines can help keep the contagion from spreading, but they cannot do the job by themselves. There has to be "negative air pressure," where it is safer for Ebola hot zone residents to stay put than to flee. 
That requires greatly reducing the rate of transmission within the hot zone, and the only way to achieve that is by using immune survivors to separate and treat the sick, a strategy developed by the Greeks 2400 years ago. The special challenge with ebola is how contagious it is to anyone who tries to provide care. By systematically hiring and developing a survivor-based treatment system that hurdle can be overcome. They can give aid without themselves becoming a vector of transmission, allowing the epidemic within the hot zone to be rolled back, reducing pressure to flee. 
 At present our national policies are working ever more powerfully in the opposite direction, creating strong incentives for infected and possibly infected people to flee to the United States from West Africa. An example of a policy that is creating an undesirable “positive atmospheric pressure” in the Ebola hot-zone (or equivalently, a negative relative pressure in the United States) is the promise that CDC Director Tom Frieden issued last week, telling the world that if anyone arrives at a major American airport with history or symptoms that indicate possible Ebola infection they will be whisked straight to the hospital, providing the strongest possible incentive for people who think they might be infected to come here for treatment.
At the same time, Frieden insists that travel from Liberia, Guinea and Sierra Leone to the United States should remain unrestricted, providing opportunity as well as incentive for hot-zone residents to flee here. From Frieden’s October 9thinterview on Fox News:
Staff from CDC and the Department of Homeland Security’s Customers & Border Protection will begin new layers of entry screening, first at John F. Kennedy International Airport in New York this Saturday, and in the following week at four additional airports … [which] … receive almost 95 percent of the American-bound travelers from the Ebola-affected countries.
Travelers from those countries will be escorted to an area of the airport set aside for screening. There they will be observed for signs of illness, asked a series of health and exposure questions, and given information on Ebola and information on monitoring themselves for symptoms for 21 days. Their temperature will be checked, and if there’s any concern about their health, they’ll be referred to the local public health authority for further evaluation or monitoring.
This funneling of hot-zone travelers through screening here in the U.S. was just made mandatory, guaranteeing care to the possibly infected. The resulting outward pressure—motivating infected people to move to a previously uninfected continent—will spread the infection, not contain it. Set aside that the CDC is supposed to give priority to American lives and should first and foremost work to keep Ebola from coming here, intercontinental spread of Ebola is a disaster for the whole world. Each breach of containment endangers everyone everywhere. 
Broad screening by it self would be fine. We have always tried to stop contagion from entering our borders. But screening together with a refusal to apply travel restrictions is an invitation to disaster, creating an obvious and powerful negative pressure on our side of the Atlantic that will suck Ebola here in volume. 
Creating negative pressure in the hot zone is not so easy
So long as the contagion keeps expanding within the hot-zone itself the pressure on residents to flee will keep increasing. But fighting transmission inside the hot zone is a labor intensive enterprise. Health care workers have to first diagnose who is infected and who is not, then isolate and treat the sick, all of which presents a high risk of transmission to the people doing this work. 
Ebola is perhaps the most infectious pathogen ever encountered, transmissible by a single particle. The repeated assurances that Ebola is not highly contagious apply only while patients remain asymptomatic. Once they start explosively erupting at both ends, protection for anyone in attendance must be perfect, which is very difficult to achieve, a factor that the CDC and our news media has been slow to acknowledge.
Three weeks ago NPR ran a happy talk segment on how easy it is to stop the spread of Ebola that completely ignored the problem of transmission through health care workers:
So to stop the chain of transmission, all health workers in Texas have to do is get the people possibly infected by the sick man into isolation before these people show signs of Ebola.
Then R0 drops to zero. And Texas is free of Ebola.
Then we all found out how difficult it is to keep health workers from getting the disease. The transmission rate, R-naught, does not drop to zero. With enough training and equipment transmission might be lowered dramatically, but only at impossible cost. Here a hospital director reacts to the CDC’s prep call (via Brian Preston):
Ebola Preparation “will bankrupt my hospital!” “Treating one Ebola patient requires, full time, 20 medical staff. Mostly ICU (intensive care unit) people. So that would wipe out an ICU in an average-sized hospital.”
At extreme expense we might be able to protect medical workers from contamination in a very limited number of Ebola cases. In Africa, forget it. But immune survivors do not need to be protected from contamination and this is a resource that Africa has in rapidly growing numbers. 
Immune survivors can make it both safer and more remunerative for hot-zone residents to stay put
Survivors have full immunity only to the Ebola strain they were infected with, but if they provide care in their local area they should be okay. Dr. Bruce Ribner onPBS:
Ebola virus is a new infection on this continent, but our colleagues across the ocean have been dealing with it for 40 years now, and so there is strong epidemiologic evidence that, once an individual has resolved Ebola virus infection, they are immune to that strain, recognizing that there are five different strains of Ebola virus.
Designate local isolation compounds for triage and treatment, drop off people and supplies, and no one comes out without a clean bill of health, bleached clothes, and a nice chlorinated shower. The immunity (in most cases) of the survivors means they could provide care without transmitting the disease, allowing the contagion to be rolled back, and the income they receive (this is where aid money comes in) would prop up the local economy, all of which would work to keep hot-zone residents in place.
If coming to America is off the table then flight from the Ebola hot-zones is a very daunting proposition. Africa is not a thriving land of opportunity and travel is more of a way to catch disease than avoid it. Thus if transmission within the hot-zone can be drastically reduced, negative atmospheric pressure is readily attainable, and this is what the use of immune survivors allows. Not being vectors, they can intercede to stop transmission in the cases under their care.
Some of these survivor health-workers will get infected with different strains and despite some cross immunity some of these re-infected health workers will surely die, but the fact that they are largely immune will allow the work of isolation and treatment to continue, which is simply not possible otherwise on any major scale.
The immune-survivor treatment strategy was implemented by the Greeks 2400 years ago
When I started advocating the immune-survivor strategy six weeks ago, I sent my post to Stanford health economist Jay Bhattacharya and he said, hey that’s what the Greeks did, sending me the following citation from Thucydides:
But whatever instances there may have been of such devotion, more often the sick and the dying were tended by the pitying care of those who had recovered, because they knew the course of the disease and were themselves free from apprehension. For no one was ever attacked a second time, or not with a fatal result. All men congratulated them, and they themselves, in the excess of their joy at the moment, had an innocent fancy that they could not die of any other sickness.
According to a report published by the CDC (back when they knew stuff) the Athenian plague could well have been Ebola. 

I am not the only one to advocate the deployment of immune survivors today. The day after I published my post Dr. Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, wrote the following in The New York Times:
The United Nations … should also coordinate the recruitment and training around the world of medical and nursing staff, in particular by bringing in local residents who have survived Ebola, and are no longer at risk of infection.
We have one immune survivor here in the United States, Dr. Kent Brantly, and with luck and prayers he may soon be joined by Nina Pham and Amber Vinson, but West Africa has a few thousand, and with the infection rate expected to soon reach 10,000 per week, that will become another 3000 survivors a week. The resource is there, we just have to use it, but the rationalizations provided by CDC Director Frieden show that he is looking in the opposite direction.
Frieden wants non-immune aid workers to go to Africa
That’s what he keeps saying whenever he tries to explain why he is against travel restrictions, that restrictions will make it harder for aid workers to travel to Africa:
One strategy that won’t stop this epidemic is isolating affected countries or sealing borders. When countries are isolated, it is harder to get medical supplies and personnel deployed to stop the spread of Ebola.
As one of the authors of whatever restrictions would be imposed, Frieden would have a chance to attach whatever exceptions he deems necessary for getting aid workers in and out, but set that aside. His premise to begin with is that outsiders should be going in and providing treatment. Like the happy talkers at NPR (who were trying to explain why Frieden is so confident that Ebola will not spread in the United States), Frieden ignores the problem of health care workers as a disease vector. About people who are being tracked and monitored he says:
The moment if they have any symptoms, if they have fever, they will be isolated. That is how you break the chain of transmission.
Yeah, not really. For a very small number of Ebola patients, at huge expense,maybe, if levels of protection and training are vastly improved. For Africa? Send in supplies and a small number of organizers at most, but no one from the outside should be sent in to deal with possibly infected subjects. They will just become disease vectors, both within Africa, and if they return without first undergoing a full period of quarantine they will bring it back here. 
Certainly don't send our military, or theNational Guard, and unexposed natives should not be recruited either. Turn the job over to the immune survivors. That is the only way to stop the contagion, and this critical resource is not here in America. It only exists in Africa, so stop bringing Ebola patients here!
Frieden keeps insisting that efforts to contain Ebola geographically will cause it to spread geographically
It is a bizarre contention. All non-government commentators regard isolation and treatment as complimentary strategies but Frieden insists they are either/or:
Restricting travel or trade to and from a community makes it harder to control in the isolated area, eventually putting the rest of the country at even greater risk. Isolating communities also increases people’s distrust of government, making them less likely to co-operate to help stop the spread of Ebola.
He is equating isolation with abandonment, which is a non sequitur. Does a patient placed in an isolation room become harder to control? Does being cared for in isolation make him more distrustful, and make observers distrustful, or does it make every one thankful? Frieden’s strained efforts to support this weak narrative are illogical to the point of dishonesty:
When a wildfire breaks out we don’t fence it off. We go in to extinguish it before one of the random sparks sets off another outbreak somewhere else.
Really, the guy’s never heard of a firebreak? We actually set fires, sacrificing part of the tree population to save the rest. Not that we should do that in Africa, but c’mon dude. Don’t just lie about stuff!
Travel restrictions may indeed have some downsides, but they also have a most important upside: they stop sick people from traveling around the world spreading disease. The question, which Frieden never even attempts to address, is whether the downsides he puts forward outweigh the upside in terms of disease transmission. Indeed, it is perfectly clear that Frieden is not accounting the upside at all, since he implicitly assumes it would be outweighed by the flimsiest of hypothesized downsides.
In reality, it is hard to think of any downside to travel restrictions that could begin to compare to the importance of keeping the Ebola-infected from freely carrying the disease wherever they want. The first imperative is to stop Ebola from making its way around the world and as director of the CDC it is Frieden’s first responsibility to make sure it doesn’t travel here. If other countries are also self-protective that is good. It will limit the spread of Ebola which makes everyone safer.
Is Frieden (and/or Obama) trying to reduce outward pressure by holing the containment vessel?
As meteorologists know, relative atmospheric pressure can be a tricky concept. Because air pushes in different places, distinguishing cause and effect can take some care, and this applies to the disease transmission analogy as well.
To achieve negative pressure in the Ebola hot-zone containment is obviously not enough. Transmission within the hot zone must be greatly reduced or else pressure to flee will build and build until it inevitably explodes. Could Frieden be looking at this looming build-up of pressure and getting the causality backwards? Is he proceeding on the idea that, if we never have containment in the first place, then the pressure cannot build enough to have an explosion?
Actions suggest that he and others may actually be trying to reduce outward pressure by getting rid of containment up front and even encouraging people to flee. Witness the “Ebola Outbreak-related Immigration Relief Measures” issued by the U.S. immigration service in mid-August, which the CDC would surely have had input on.
Some of the measures are reasonable, allowing “Nationals of Guinea, Liberia and Sierra Leone Currently in the United States” to stay here for now instead of forcing them to go back to the hot zone when their visas expire, but the measures gratuitously go much further, providing extreme incentive for residents of these countries to get themselves into the United States ASAP.
The really damaging relief measure (pressure relief measure?) is the first, which offers an opportunity for, “[c]hange or extension of nonimmigrant status for an individual currently in the United States, even if the request is filed after the authorized period of admission has expired.”
A change of status means a change from non-immigrant to immigrant status, thus any West African who is here on a tourist visa is eligible to be immediately switched to permanent resident status, leading to citizenship, and here’s the kicker: as Doug Ross noticed, there is no cut-off date for who is eligible for this change of status.
Instead of applying only to West Africans who were already here in mid-August, any Ebola-zone citizens who can get themselves over here on a tourist visa are immediately eligible to switch to permanent resident status, providing huge incentive for immediate mass outflow from West Africa to the United States. Obama/Frieden are offering them a once-in-a-lifetime jump-to-the-head-of-the-line opportunity to become American citizens.
We know Obama’s motivation, but why is the CDC going along?
President Obama, being a politician, can of course have political motivations for incentivizing West Africans to come here for citizenship. His intentional collapse of our southern border suggests that one of the ways that he wants to “fundamentally transform America” is by importing a new electorate, more to his liking. (DHS let a huge contract for the internal transport of unaccompanied illegal alien minors months before the vast wave of “unaccompanied minors” arrived, proving that the entire crisis was engineered by Obama.)
But CDC Director Frieden is supposed to be non-partisan, guided only by the objective requirements for keeping his countrymen safe from disease. How can a medical doctor be supportive of a ramped-up influx of immigrants from West Africa that is highly incentivized to carry Ebola?
Friedan’s big career-making achievement was dramatic reductions of tuberculosis in New York City and India, accomplished by systematic tracking, isolation and treatment of the infected. His oft-repeated mantra on Ebola is the same. “We know how to stop Ebola,” he says, by tracking, isolating, and treating infected individuals. Could he be fixated on tracking as a means?
Frieden wants people who could be infected with Ebola to fly so that they won’t travel “over land”
Note the particular language Frieden uses to explain why he thinks travel restrictions will be counter-productive. He keeps saying he wants the possibly infected to travel by means that enable tracking. That points directly to a preference for airline travel:
FRIEDEN: Right now, we know who’s coming in. If we try to eliminate travel, the possibility that some will travel over land, will come from other places, and we don’t know that they’re coming in, will mean that we won’t be able to do multiple things. … Borders can be porous — may I finish? – especially in this part of the world. We won’t be able to check them for fever when they leave, we won’t be able to check them for fever when they arrive. We won’t be able, as we do currently, to take a detailed history to see if they were exposed when they arrive.
When they arrive, we wouldn’t be able to impose (ph) quarantine as we now can if they have high-risk contact. We wouldn’t be able to obtain detailed locating information, which we do now, including not only name and date of birth, but e-mail addresses, cell phone numbers, address, addresses of friends, so that we could identify and locate them.
We wouldn’t be able to provide all of that information, as we do now, to state and local health departments, so that they can monitor them under supervision. We wouldn’t be able to impose controlled release, conditional release on them, or active monitoring, if they’re exposed, or to, in other ways…
The whole point of tracking is to stop further transmission so that we don’t have to do more tracking. The fact that a mode of travel enables tracking isn’t a plus if it also multiplies the need to track, as around the world commercial jet travel obviously does. In Frieden’s accounting the smallest amount of un-tracked contagion is more dangerous than a wide open and highly incentivized avenue of tracked contagion, because this is what we are talking about here.
The “overland” spread of Ebola that is Frieden’s sole concern would be extremely difficult under a travel ban. Even if frightened people could make their way out of Liberia and Guinea and Sierra Leone by ground travel (very difficult, snce many neighboring countries have closed their borders) they would still need to fly to reach the United States, which requires a visa, which requires a passport, which would still identify them as coming from a hot-zone country. The other possibility is that they fly to Mexico or Canada and travel overland at this end, but a) these crossings are within in our power to control, and b) if we impose a travel ban then Mexico and Canada will surely follow suit.
Frieden focuses entirely on the relatively tiny number of cases where a few West Africans might still get in by these untracked routes (a number that might well be decreased, not increased, by travel restrictions), and he completely ignores ignores the vast majority of cases where travel restrictions would keep the possibly Ebola-infected out. This selective accounting is not legitimate. It is basic economics and basic epidemiology that all impacts have to be fully accounted. Only looking at untracked flow is like buying merchandise for $100 a pop, selling it for $1 a pop, and thinking you are making money because you are only counting the flow of $1 receipts.
NIAID head directly mis-states travel requirements
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, does not seem to be aware of how travel documentation works. On Sunday he claimed that:
“If you say, ‘Nobody comes in from Sierra Leone, Liberia or Guinea,’ there are so many other ways to get into the country. You can go to one of the other countries and then get back in [to the United States].”
Wrong. Escapees from the hot-zone would only be able to get here via “other countries” if those other countries start issuing them passports that hide their true origin. Frieden and Fauci are doctors, not travel agents, but the entire USCIS knows that their claim about border hoppers being able to fly to the United States is wrong.
Regardless of Fauci’s confusion, the underlying error is still the same. Even if travel restrictions did somehow lead to an increase in un-tracked travel across the Atlantic (highly dubious), this increased avenue for Ebola transmission would still be tiny compared to the vast wide-open “above ground” highway for Ebola transmission that a travel ban would close off.
These supposed experts are acting as if there is no danger so long as we can track transmission, ignoring what a desperate game it is try to smother every outracing tendril from each outbreak. It’s like trying to stamp out an intrusion of cockroaches before any can escape through a crack.
Learning the wrong lesson from Nigeria’s close call
With heroic effort Nigeria just pulled off the squash-all-the-cockroaches feat, dedicating thousands of man hours of urgent detective work to successfully run down and isolate each multiplying pathway of Ebola exposure before they could multiply out of reach and consume a city of 21 million.
It was a very near thing and Frieden and Fauci are clearly learning the wrong lesson from it. They view it as confirmation that tracking works and can “stop Ebola in its tracks,” but the real lesson of Nigeria is the tremendous danger that just one infected airline passenger can pose. Realizing how lucky they were, Nigeria learned its lesson and stopped its hot-zone flights.
Much better not to let possibly infected people enter in the first place. Once an Ebola-infected person arrives a country might be quick enough to stop the contagion by tracking, monitoring and isolating individuals, but if the contagion gets away from them they will have to stop it the old fashioned way, the Greek way, by making use of the immune survivors as they emerge one by one from the spreading catastrophe.
Every nation has to be prepared for those same three stages of Ebola prevention and response. First we try to keep it from entering. If that fails then we try to contain the outbreak with tracking, monitoring and isolation of exposed individuals, and if that fails and there is an epidemic, only immune survivors can roll it back. Frieden and Fauci are fixated only on the middle third of this puzzle, the tracking. They aren’t concerned with keeping Ebola from getting here and they aren’t looking at how to fight it if it breaks out. Neither are they merely absent from these other battlefields but their fixation on tracking has them aggressively bringing Ebola here when the only people who can safely treat the disease are in Africa.
A perfect storm of illogic
Put Frieden’s apparent belief that tracking is a panacea together with his apparent confusion about cause and effect and they support each other. This seems to be his actual thinking: that if we let the infected out of the hot zone (while carefully tracking) then there won’t be an explosion because the pressure won’t have a chance to build up.
Could it be that simple, that he just doesn’t understand atmospheric pressure, where the whole point of creating negative pressure is to stop the outflow of the pathogen, so if pressure is reduced by the outflow of the pathogen that means we failed? Is the guy just that stupid? Or does he have some horrific political agenda like President Obama? (Definitely possible, since untracked TB and other infectious diseases pouring over our unenforced southern border elicit no protest from him.)
Either way, Congress better provide some countervailing force and quickly because the CDC is working hard to bring the negative pressure to our side of the Atlantic, sucking Ebola in. It is clear what we should be doing: imposing travel restrictions and using hot-zone Ebola survivors to separate and treat the newly infected. Then the problem won’t just stay in West Africa, it will be solved there.
The alternative, if Obama and Frieden can’t be stopped, is that we suffer our own Ebola epidemic, where the only way to avoid decimation or worse will be to deploy our own rapidly growing army of immune survivors. It’s either Thucydides in Africa or Thucydides in America, our choice.

UPDATE: Spencer case shows that we do NOT want free travel for returning aid workers, and it shows how quickly the tracking-hope could disappear

Spencer had been working with ebola infected people in Africa, came  back to America, started feeling weak, and the next day used several subway lines to go on an across-the-city bowling trip. But this was still a best-case-scenario because when his symptoms started to get worse Spencer knew it was probably ebola, isolated himself, and let everyone know.

The Dallas case was a similar best-case-scenario. Duncan knew he had recent physical contact with a person who died of Ebola. That's why he initially went to the hospital when he only had a mild fever, and when the ambulance later came to get him at his apartment his daughter told the EMTs that he likely had Ebola, so everybody was on alert. They still made mistakes, but nothing compared to what would have happened if they had no idea what was the matter with him.

The nightmare scenario is what happens when some ignorant person comes down with Ebola and has no idea he has Ebola. Suppose an out-of-it druggie were to pick up Ebola from Dr. Spencer's long trek through the subway system--maybe Spencer coughed on somebody, who knows, the guy was full of Ebola at that point--so a week or two from now this hapless druggie spends a couple of days on the streets and in the subway while he is in the massive shedding stage of Ebola infection, bleeding, puking and crapping in public rest-rooms and alleys and tracking his mess through public places.

Then it's goodbye to any hope for tracing the pathways of possible exposure. If it gets on the seats, grab-rails and hand straps of a handful of subway cars it will pass hand to hand, doorknob to doorknob, far beyond the subway system in a matter of hours. A single germ is infective, the tiniest drop of blood contains millions of germs, and we'd have this disintegrating person slathering infectious fluids everywhere he goes. If this just goes on for one day there will be a rampant epidemic starting in NYC but not stopping there.

The danger is EXTREME, yet not only are Frieden and Obama still adamant against travel restrictions, but they are at the same time providing huge incentives for possibly Ebola-exposed people to make use of that allowance to come here, both in the form of promises of first-rate care and through a once-in-a-lifetime offer of U.S. citizenship for anyone who can himself here from the Ebola hot zone, creating massive positive pressure for Ebola to flow out of the hot zone and into the United States. These policies are horrific, and the consequences will be too.

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