Tag Archives: Dallas

Ebola’s mortality rate may depend on several factors:

  • The particular strain of Ebola.
  • The age and underlying health of the patient.
  • How ill the patient is when s/he begins receiving care.
  • The quality of the care the patient receives.
  • The availability of antibody treatments such as ZMAPP or serum taken from survivors.

Prior Outbreaks

Before this year most Ebola outbreaks have been confined to rural areas, and treatment has been what was feasible in a tent. The West African epidemic is of the Ebola Zaire strain, for which WHO reports mortality rates from prior epidemics ranging from 44% to 90%. [WHO 9/14]

West Africa

It was initially thought that the mortality rate for the West African epidemic was around 55%. [Reuters 8/5/14]  In September, however, a scholarly article in the New England Journal of Medicine calculated the mortality rate in Guinea, Liberia and Sierra Leone at around 70%. [NEJM 9/23/14]  A Sierra Leone study of 44 patients [Reuters 10/29/14] showed 74% overall mortality, but broke the figure down in illuminating ways:

  • 57% of people under age 21 died, compared to 94% of those over the age of 45. Older patients have greater mortality risk.
  • 33% of patients with less than 100,000 copies of the virus per milliliter of blood at diagnosis ultimately died, compared with 94% of those whose had more than 10 million copies per milliliter. As we’ve previously suspected, mortality is highly dependent on how sick a patient is when treatment starts.

A thrilling anecdote from Liberia is also suggestive: A student nurse named Fatu Kekula cared for four household members, and managed to save three of them, achieving a 25% mortality rate. [LA Times 10/6/14]  She avoided infection herself using a resourceful combination of surgical gloves, plastic bags, raincoats and copious amounts of chlorinated water. Critically, she was able to give them IV drips, and she was on call essentially 24/7. What happened to any four patients has no statistical significance, but the demonstration that such a good outcome is even possible is heartening.


Nigeria had an outbreak sparked by a single air traveler from Liberia. Despite many high-risk contacts — and many incidents of quarantine-breaking and other misconduct — in the end there were only 19 cases, of which 7 died, for a mortality rate of just 37%. [WHO c.10/15/14] The number of cases is small, so this figure isn’t too statistically significant. One may speculate, however, that the lower mortality rate in Nigeria reflects two main factors: (1) better quality of health care, and (2) the fact that many patients were being monitored daily, so were presumably given care as soon as they began showing symptoms. The single patient who traveled to Senegal survived, and the child who traveled to Mali died, but neither case tells us anything about overall mortality rates.

The U.S. and Europe

The number of cases treated in western countries is also small, so even less statistically meaningful than the figure for Nigeria. As in Nigeria, most of these patients received treatment as soon as symptoms were noticed, which may be a significant benefit. Disregarding patients still in treatment, the figures, from the excellent New York Times Ebola Facts page, are as follows:

  • United States: 8 patients, of which 1 died and 7 recovered, for a mortality rate of 13%.
  • Europe: 8 patients, of which 3 died and 5 recovered, for a mortality rate of 38%.

Since the figures are so small the difference between Europe and the U.S. could easily be random. But it’s interesting to note that Thomas Eric Duncan, the patient who died in Dallas, had initially been turned away by the hospital, and only started receiving care after he had become so ill that he had to be transported by ambulance. His two nurses, in contrast, began receiving care soon after they first developed fevers, and both have recovered fully. CNN’s discussion of the factors that affect survival in western countries is a bit dated but still worth a look: [CNN 10/20/14]

Dr. Paul Farmer, a Harvard professor and co-founder of the charity Partners in Health, has expressed the hope that with top-notch care the mortality rate for Ebola could be as low as 10%. [London Review of Books 10/23/14] This isn’t inconsistent with the U.S. experience, keeping in mind the low sample number. It will be wonderful if it proves possible to substantially reduce the mortality rate in the African setting. An improved standard of care would not directly help stop the epidemic, but it would indirectly contribute to stopping transmission if it encouraged more people to enter clinics rather than staying at home, which increases the risk of infecting other household members.

Added 10/31/14: Paul Farmer’s emphasis on quality of care implicitly criticizes the way some twenty Ebola outbreaks have been handled since 1976, most notably by Médecins Sans Frontières / Doctors Without Borders (“MSF”). I would characterize the MSF approach as embodying three priorities:

1. Stop the Outbreak, by Isolating Patients.
2. Protect Staff from Getting Infected.
3. Cure as Many Patients as Possible.

For nearly 40 years MSF has been stunningly successful at achieving these goals, often in remote rural settings with extremely limited infrastructure. I’m sure Dr. Farmer would hasten to agree that we owe MSF and its peers an enormous debt of gratitude for their extraordinary service to humanity.

My own view is that MSF’s priorities are correct. Stopping the outbreak must always be job #1. One wants also to minimize risk to staff, but some risk is inevitable and must be accepted in order to end an Ebola outbreak. Curing patients is every doctor’s objective, but if a choice must be made stopping the epidemic is more important. Similarly, if staff start becoming infected at excessive rates we would lose the ability to either stop the outbreak or cure patients.

Saying that these priorities are correct does not, however, answer the question of how much can and should be done to cure patients.

My understanding, for example, is that MSF typically does no blood work apart from an initial test to confirm the diagnosis and final tests to confirm a cure. Often there would be no lab available to do additional testing anyway; it’s difficult and risky for a staff member wearing goggles and three layers of gloves to take a blood sample; puncturing the skin of an Ebola patient can lead to infection and/or uncontrolled bleeding; getting a blood sample takes precious time away from other patients; blood tests would cost money that might be better spent elsewhere; etc. etc. When regular blood tests are available, as in western hospitals, care can be customized to the patient’s individual needs. Infections can be identified and halted; imbalances in electrolytes identified and corrected, etc.

I presume that MSF would agree that a higher standard of care would be desirable, wherever it is feasible. The real question in each situation is where do you strike the balance between an aspiration for the best standard of care and the need to quickly isolate patients to stop the outbreak, as well as constraints of money and infrastructure. It may be that the MSF approach should be implemented quickly as soon as an outbreak is identified, then upgraded as time and resources permit.

Dr. Farmer’s push for a higher standard of care is directly opposed to a recent WHO proposal for “clinics” that would isolate patients but offer little or no medical care. [AP 10/2/14] This is a desperate response to the situation in Monrovia several weeks back where patients were being cared for at home — often infecting many household members — because there were no beds available. Since there now appear to be open beds it may be hoped that we don’t have to do in this inhumane direction, which explicitly sacrifices patient care to the overriding goal of stopping the epidemic.  [Economist 11/1/14]

Antibody Treatments

A handful of U.S. and African patients received the few available doses of ZMAPP, an artificial antibody treatment that has been successfully tested in monkeys. The U.S. patients survived and several of the African patients died, but the numbers are too small to reach any conclusions about its effectiveness. Similarly, several U.S. patients received antibodies in serum taken from survivors. The fact that they survived is encouraging, but again the numbers are too small at this point to support conclusions.


There are really only three things you need to know about Ebola. Each of them is a serious problem, of a distinct type. But the only solution to all three issues is to end the epidemic in West Africa as soon as possible.

1. Humanitarian Crisis in West Africa

In case you’ve been distracted by the news from Dallas, the real issue is in Liberia, Sierra Leone and Guinea, where the epidemic is continuing to grow exponentially. In case you aren’t aware how bad it is my last blog post will better inform you. These countries urgently need our help to moderate and eventually end this terrible situation.

2. Risk of Spread to Other Poor Countries

There will continue to be isolated cases of Ebola in the Western world: A traveler will occasionally fall ill, as in Dallas. A healthcare worker will occasionally be infected, as in Spain. Each patient may possibly infect a few more people, but with care and attention any little outbreak should be readily brought under control. Hard though it is to believe, Ebola really isn’t very contagious, relative to common diseases like measles and the flu. The total number of people affected in developed countries will probably be on the order of how many people are struck by lightning. Accidents, suicides, and many other diseases present far greater risks in our world.

In a poor country, however, with weak healthcare infrastructure, and crowded slums, Ebola might gain a foothold. It is hard to imagine that the world would ever again allow an epidemic to get as far out of hand as the one in West Africa, but it’s possible. And that has the potential to multiply the disruption, sickness and death of the current epidemic many fold.

3. Risk of Mutation

The last worry is the possibility that Ebola could mutate to become more infectious. The Ebola Reston strain seemed to pass between monkeys through the air, so this anxiety isn’t entirely fanciful. [CNN 10/6/14] The best way to prevent such a mutation is to stop the cycle of human-to-human infection in West Africa. The more rolls of the dice Ebola gets the greater the risk that a mutation will increase its ability to infect. Which could obviously be a big problem.

Conclusion: We Must Stop the Epidemic

The brouhaha about Dallas, and most recently about the Spanish nurse’s puppy, is predictable, but we need to return our attention to the main point. For all three of the reasons mentioned above job #1 is ending the epidemic in West Africa. Cutting off travel and the like may seem to make us safer, but in fact they make us less safe, by exacerbating all three of these primary issues. We’ve got to stop the epidemic!

(I’ve oversimplified a bit: If you’re a healthcare worker you need to know more, precisely in order to avoid as many as possible of the blunders which have characterized the responses in Dallas and in Spain. And if you’re in West Africa of course you need to think about a lot of additional issues.)

Like sparks from a burning building, travelers are carrying Ebola around the world. What’s been happening? What will happen? What can we do?

The Ebola Diaspora

People travel for lots of reasons, some related to the epidemic, some not.

  • Now as always people will want to travel for business, tourism, or to spend time with family or friends. With Ebola increasingly out of control more and more of the people traveling from West Africa will turn out to be infected. I’ll address later in this post the idea of stopping travel altogether, but in short it wouldn’t work, except perhaps to delay the inevitable.
  • As life becomes more difficult in the affected countries people will have an additional reason to travel, seeking either a temporary respite or an extended or permanent refuge. If things get really bad this could change from a trickle to a panicky exodus.
  • People who have been exposed to Ebola, but are not yet symptomatic, may have a special incentive to travel to a country with a modern healthcare system. Such passengers also have a strong incentive to lie about their Ebola exposure, as the traveler from Liberia to Texas apparently did. [CNN 10/3/14] This could be a particular problem for developed Western countries, but also for more prosperous African countries such as Nigeria and South Africa.
  • Fever monitors in airports should prove to be an effective method of barring symptomatic patients from air travel. Update 10/6/14: It has been suggested that ibuprofen could be used to hide a person’s fever in order to get a symptomatic patient through airport screening. [Reuters 10/3/14]  I don’t know whether this is true, but if so it would be a weakness in the screening process.
  • Symptomatic patients may still slip across porous borders on the ground, but airport controls somewhat reduce the spread of Ebola and nearly eliminate the already-low risk to the airplane’s crew and passengers. Port authorities in the affected countries and their neighbors are attempting to do the same type of screening of ship’s crews. [AFP 9/29/14]

The bottom line is that people infected with Ebola will travel to other countries, on the ground and by air and by sea. Wherever they go they will fall ill, and potentially infect others, setting off local Ebola outbreaks. Everything will depend on the location and the response. Stable countries with capable healthcare systems and effective governments should be able to snuff out their Ebola outbreaks fairly easily, depending on the the level of noncompliance they encounter. Poor countries with crowded slums and limited healthcare may not be so lucky.

What’s Been Happening?

Apart from medical evacuations we know of just three cases in which someone infected with Ebola traveled outside of Guinea, Liberia and Sierra Leone.

Nigeria – Patrick Sawyer

Patrick Sawyer, a Liberian-American diplomat, traveled on July 20 from Monrovia to Lagos via Togo despite having severe Ebola symptoms, including vomiting repeatedly during his flights. He collapsed in the airport and was taken to a hospital where he died a few days later, but not before infecting half a dozen people who themselves went on to infect a dozen more. Nigeria identified and tracked 894 contacts of Sawyer and other infected people, of which 20 came down with Ebola and 8 died. [Washington Post 9/30/14] Details are in my earlier posts: Arrogance and Privilege Imperil Nigeria’s Attempt to Contain Ebola and How Contagious is Ebola?

This story involves multiple instances of noncompliance with quarantine orders and lying, as well as many cases in which hospital staff were unnecessarily infected. Nevertheless, Nigeria’s persistent contact tracing and isolation measures, and capable healthcare system, eventually brought the outbreak (apparently) to a close.

Senegal – A Guinean Student

A 21-year-old student named Mamadou Alimuo Diallo was under surveillance in Guinea because several relatives had fallen ill with Ebola. He nevertheless traveled by car to Dakar, Senegal, despite the fact that the border between Guinea and Senegal was supposed to be closed. He arrived in Dakar on August 20, and stayed in the large household of his uncle. He began feeling ill on the 23rd and went to a medical facility seeking treatment for fever, diarrhea and vomiting, but concealed his contact with Ebola patients, and was sent back to his uncle’s home. He was eventually admitted to a hospital for Ebola treatment on the 26th. [USNews 9/1/14]  Some 67 people with whom the student had been in contact were monitored, but none came down with the disease. The student recovered and returned to Guinea. [Modern Ghana 9/10/14]

Senegal apparently did a good job of contact tracing but really just got lucky, since this situation illustrated a lot of problems:

  • The student broke quarantine in Guinea.
  • The student was able to get into Senegal despite the fact that the border was supposedly closed.
  • The student lied about contact with Ebola patients on the 23rd, putting medical staff and family members at risk by going back to his uncle’s home.

It may be that Senegal’s medical facilities used better precautions than those in other countries, or it may be that the student was for some reason just not very infectious. But you couldn’t even call this an outbreak since there was no transmission of the virus in Senegal.

Dallas – Thomas E. Duncan

Thomas Duncan is a Liberian who traveled by plane from Monrovia to Dallas, Texas, arriving on Sept. 20. He lied on an exit form which asked whether he had had any contact with Ebola patients, since on Sept. 15 he had helped carry a stricken neighbor back into her apartment (after she had been turned away from a hospital). His temperature was taken at the Monrovia airport but was not elevated. [NYT 10/2/14]  On the 24th he developed symptoms and on the 26th went to the Texas Health Presbyterian Hospital Dallas. Although he told hospital staff that he had recently traveled from Liberia this information didn’t reach the diagnostic team and they sent him home. Update 10/4/14: The hospital has changed its story and admitted that in fact the entire diagnostic team had access to the fact that Duncan came from Liberia. [NYT 10/3/14] Reportedly, however, on his first hospital visit Duncan falsely denied having contact in Liberia with anyone who was ill. [AP 10/2/14]  On the 28th Duncan was taken to the hospital by ambulance and placed in isolation, with laboratory confirmation of Ebola on the 30th. [NYT 9/30/14]

The people at greatest risk were the four people in the apartment where he stayed in Dallas. They were initially told to stay at home, but were “noncompliant,” including sending at least one of their children to school! [Dallas Business Journal 10/2/14] Formal quarantine orders were then issued requiring them to stay home and not to receive visitors, and a police guard was posted. [Yahoo 10/3/14] Bureaucratic snags delayed cleaning of the contaminated apartment for several days after Duncan went into hospital. They subsequently have been moved to a lovely isolated home donated by a member of “a Dallas faith community.” [NYT 10/3/14]

A total of 12 to 18 people are believed to have had direct contact with Duncan, and they may in turn have had contact with around 100 other people. Those with direct contact are being monitored. This includes 5 school-age children. [Dallas Business Journal 10/1/14Updated 10/4/14: About 50 people are being monitored daily, of which 10 had direct contact with Duncan. [CDC 10/4/14]

Lots of mistakes have been made already, and it’s reasonable to guess that several people will pay for them with their lives:

  • Duncan shouldn’t have traveled or stayed with his relatives so soon after his contact with an Ebola patient, and he shouldn’t have lied about it on the exit form.
  • It’s incredibly stupid that the hospital sent Duncan home after he presented with a fever and told them he had come from Liberia.
    • Very possibly inadequate infection prevention procedures were taken while he was in the hospital, which presents a risk that healthcare workers were infected. Patrick Sawyer infected several doctors and nurses and the entire hospital had to be closed for a month-long decontamination! [Africa Independent Television 9/9/14]
    • This also of course increased the risk to the family where he was staying and any other people he contacted over the next couple of days.
  • It’s mind-boggling that students who had direct contact with Duncan might have been sent to school! And the other unstated “noncompliance” by the household where Duncan had been staying is worrisome.
    • Nigeria closed all schools in the entire country at the height of its Ebola outbreak to protect its children!  [BBC 8/27/14]
  • The delay in cleaning the apartment is inept but in point of fact those people are all so thoroughly exposed that it may not make a difference.

Since the mean incubation period is 11 days and Duncan’s symptoms started on Sept. 24 we can expect the first wave of infections in a few days, with hospital staff following a few days later. That’s if he’s as infectious as Patrick Sawyer; if instead he’s like the Senegal student nobody will be infected!

Mali – The Little Girl With a Nosebleed

Added 10/29/14. On October 19 a two-year-old girl was taken by her grandmother on public transport from a funeral in Guinea to Kayes in western Mali, including a two-hour stopover in Bamako, Mali’s capital and largest city. The child had developed a nosebleed in Guinea, so was symptomatic for the entire trip. The child was examined by a healthcare worker on Oct. 20, admitted to a hospital on Oct. 21, tested positive for Ebola on Oct. 23, and died the next day. Initially, some 43 close contacts were monitored, including 10 healthcare providers. [WHO 10/24/14]  This unfortunately has the potential for several to many infections, especially including the healthcare workers. The silver lining is the fact that the initial case was — eventually — identified, so her contacts could be traced. “If you have one case very early on and you catch it, you’re actually lucky,” says [Dr. Samba Sow from the National Center for Disease Control, CNAM, in Bamako] “If you don’t detect that first case you run the risk of people who are contagious staying in the community without being reported and that’s when you run the risk of an epidemic.” [VoA 10/29/14] At last report 82 contacts were being monitored. [Reuters 10/28/14]

Update 10/31/14: It now appears that the little girl traveled on buses and taxis or otherwise had contact with 141 people, of whom 57 have not yet been identified and found. [Reuters 10/31/14] This could be a disaster for Mali, or wherever those people were going. Or the day could be saved once again by the limited contagiousness of the Ebola virus.

What Will Happen?

Travelers infected with Ebola will continue to pop up from time to time, all over the world. The outcome in each case will depend on intelligence, resources, compliance with quarantines and luck.

  • One assumes that the resources available will enable developed countries to stop Ebola fairly quickly. The classic technique of isolation, contact tracing and monitoring has worked in dozens of rural outbreaks as well as in Nigeria, despite serious noncompliance. 
  • This should be true in Dallas, despite stupidity at the hospital and noncompliance by the family which have increased risk, and may cause unnecessary deaths.
  • The real problem is when Ebola pops up in a poor country with a weak healthcare system, especially in a crowded slum, and especially when there are endemic diseases like malaria that can cause similar symptoms. If Ebola gets established in such a situation it could become another Liberia.

Update 10/6/14: Northeastern University researcher Alessandro Vespignani has developed a computer model which predicted, as of Oct. 1, the likelihood of an infected person traveling to particular countries over the first three weeks of October. [Boston Globe 10/1/14] The ten countries with the highest probabilities are, in order: Ghana (46%), France, Senegal, U.S. (25%), Ivory Coast, U.K., Nigeria, Mali, Belgium and Morocco (about 10%). Of course the U.S. has already identified one such traveler, but it would seem that we still have about a one in four chance of encountering another by the end of the month. One question which isn’t clear from the article is whether the investigators took into account the possibility of a travel bias towards countries with good healthcare systems by people who are concerned about the possibility of having been exposed to the virus. The investigators are posting updating predictions at this link: Ebola – MoBS.

As noted above, the big concern is when one of these people arrives in a poor country with a weak healthcare system. The biggest worry is Ghana, followed by Senegal, Ivory Coast, Mali and Morocco. Nigeria is also high on the list but they showed considerable skill in quashing the Patrick Sawyer outbreak so may be somewhat less at risk (unless the virus gets loose in the ungovernable northern region). The slums of India or South America would also be quite vulnerable but the likelihood of travel there is much less.

What Can We Do?

There are just a few things we can — and must — do.

Limit Travel From Affected Countries?

There will no doubt be a move in America to bar travelers from the three affected countries (Guinea, Liberia and Sierra Leone). This has a superficial appeal, on the same reasoning as the cordon sanitaire around an epidemic ravaged city. (This is discussed in an earlier post: Ebola Quarantines) WHO takes the view, however, that travel bans are counter-productive. [AlJazeera 9/22/14] Not only do travel bans have detrimental economic consequences, but they can worsen the epidemic itself by hindering relief efforts. 
This article makes the case rather persuasively:

It’s also questionable how effective a travel ban would be. The Guinean student demonstrated how porous African land borders are, even when theoretically “closed.” Someone who really wanted to leave the affected countries could get out. Rich and privileged people may have multiple passports, that could be used to conceal their nationalities and/or their itineraries. And there would always have to be exceptions, of one sort or another. A ban might slow the process of seeding Ebola all around the world, but it wouldn’t altogether stop it. Update 10/6/14: The Northeastern University computer model mentioned above elegantly quantifies this. Even with an 80% reduction in flights from the affected countries the probability of an infected person arriving in a given country is only delayed by 3 to 4 weeks. [MoBS Lab 10/1/14]

Update 10/6/14: Despite the arguments against it, I see two possible reasons why a travel ban may nevertheless happen: (1) it may be forced on politicians by a panicky electorate, and/or (2) the numbers of infected travelers may become excessive, due either to a general exodus or medical tourism by people who suspect (or know) that they are infected.

The five-day Hajj (Muslim pilgrimage to Mecca) started on Oct. 2. Saudi Arabia denied visas to residents of the three West African countries, and asked travelers to fill out a medical screening form that details their travels for the previous three weeks. [BBC 10/2/14] Of course people may lie, but it certainly is to be hoped that this year’s Hajj at least will be Ebola-free.

Quarantine Arriving Travelers

Travelers from suspect countries could be quarantined for 21 days before being allowed into the country. This is a tried and true Medieval technique but it’s a really poor fit with our fast-paced globalized world. A non-starter.

Continue to Screen Travelers

Thomas Duncan’s temperature was taken at the Monrovia airport as part of the screening system put in place following the Patrick Sawyer debacle. This part of the process worked as intended, to keep symptomatic travelers off planes. He was asked all the right questions; though unfortunately he lied. This sort of screening is the best you can do, and it’s helpful, even though it can’t prevent pre-symptomatic people like Duncan from traveling.

It would be helpful to add arrival screening of people who have been in affected countries (or U.S. states!) but it’s difficult to identify those people and it would be a huge project to screen everyone on arrival.

Be Prepared

Healthcare providers all over the world must be alert to the possibility of Ebola. In this case Duncan didn’t lie about coming from Liberia (although there’s no indication he told anyone about his contact with an Ebola patient) but there was a lapse in communication within the hospital. This sort of mistake can be fatal! Both to healthcare providers and others who may be needlessly exposed when an Ebola patient is sent home.

Poor countries with weak healthcare systems must be especially vigilant to spot any unusual patterns of disease or death before Ebola has a chance to get intrenched.

There’s not much we can do as individuals, except perhaps to practice good general hygiene, including frequent hand washing. Oh, and if someone is visiting from West Africa feel free to ask whether they’ve had close contact with Ebola patients in the last three weeks…

End the Epidemic

The only definitive solution is to end the West African epidemic. In addition to compelling humanitarian reasons we need to wipe out Ebola everywhere (in humans, anyway) in order to feel fully safe in our own lives.

In April, early in the West African epidemic, the New York Times published an Op-Ed piece entitled “Ebola Virus: A Grim, African Reality.” It closed with this paragraph:

Ebola in Guinea is not the Next Big One, an incipient pandemic destined to circle the world, as some anxious observers might imagine. It’s a very grim and local misery, visited upon a small group of unfortunate West Africans, toward whom we should bow in sympathy and continue sending help. It’s not about our fears and dreads. It’s about them.

I felt then as I feel now: Ebola is not just an African problem, it’s a human problem.