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Ebola will be back, because there are animal reservoirs, but it’s great news that fourteen days have gone by since the last known case in the D.R.C. The outbreak will not officially be declared over until 42 days go by (twice the maximum incubation period of 21 days) since the last known case, but the end is in sight. Reuters, 3/3/20.

The existential threat posed by Ebola has been nearly eliminated by the development of effective vaccines that can protect healthcare providers and wide rings of potential contacts, as well as the deployment of rather good therapies. A mutation might temporarily slip this leash, but one can be rather confident that a vaccine against any variant could be developed rather quickly.

The world’s attention now turns to COVID-19…

The Ebola vaccine was an enormous advance, but it only works before infection. Two antibody therapies – ZMapp and remdesivir — cut the death rate by a factor of two or three when given soon after infection, but 1/4 to 1/3 of patients still died. Now two new monoclonal antibodies cut the death rate to around 10% when given soon after infection. New York Times, 8/12/19.

This is an absolute game changer. Not only will it cure many more people, but it will afford an incentive for people who may have been exposed to come in for treatment instead of shunning clinics as death traps. Even in the dangerous conflict zone of the current epidemic this may tip the balance in favor of humanity. It also points the way for development of similar treatments for related diseases such as Marburg.

We owe a debt of gratitude to the individuals and companies who have doggedly pursued the antibody approach.

Update 8/22/19: An article in the LA Times points out that it’s premature to call the new treatments a “cure” since 10% of patients die even when treated early, and survivors are often still impaired. I considered raising this point in my original article but decided that the positive impact of using the somewhat exaggerated term outweighed the risk of creating unsupportable expectations. As I point out, as does the LA Times article, getting people to treatment centers early is critical for their survival prospects as well as for quelling outbreaks. Saving 90% from a disease that kills 70% of untreated patients is a worthy goal even though the remaining deaths are still tragic, and might disillusion some who relied on the term “cure” without reading the fine print.

The Democratic Republic of the Congo (the “DRC”) has a good record of controlling Ebola, but this time is different.

The central problem is that standard procedures cannot be fully implemented because the outbreak is in a conflict zone, North Kivu in the northeastern part of the DRC. Violence has been so serious that the CDC has withdrawn three of its Ebola experts to Kinshasa, 1,500 kilometers away. Axios, Oct. 18, 2018. Update: The director of the CDC argued for leaving experts in the outbreak zone but was overruled by the Trump administration. Stat, Oct. 24, 2018.

Additionally, it is becoming clear that a much greater proportion of new infections than in prior outbreaks are in children. This may be due to traditional healers who are unwittingly infecting children brought to them for treatment of malaria. PBS, Oct. 20, 2018. This new vector of transmission needs to be confirmed and controlled.

The PBS report also notes that,

Over the past three or four weeks, a growing proportion of cases have been people who were not identified as contacts of previous cases. And increasingly, even retrospective attempts to figure out how these people became infected are failing to chart the links.

This, along with the growth in cases, is a key indication that the epidemic is spinning out of control. Update: An excellent piece in Stat has a slightly more optimistic spin, saying that community cooperation is increasing. Stat, Oct. 25, 2018.

WHO expressed concern last week but failed to declare the epidemic a public health emergency of international concern (a “PHEIC”). WHO’s Statement, 10/17/18. WHO is understandably afraid of causing unnecessary alarm, but critics fear a repetition of its tragic inaction in the early stages of the West African epidemic. Stat, 10/17/1.

The availability of an effective vaccine is a tremendous advantage, but you have to know whom to immunize, and the conflict is impeding the standard contact-tracing process. The new transmission mode to children must be found and countered. It’s still possible that the North Kiva outbreak can be confined, but the risk that it will blossom into a big regional epidemic has dramatically increased.

For the first time, a suspected Ebola case has appeared in the Congo’s conflict zone. A doctor in the town of Oicha, in North Kivu province, is strongly suspected of being infected, despite having initially tested negative for the virus.  “Oicha is almost entirely surrounded by ADF Ugandan Islamist militia, and there are ‘extremely serious security concerns’ following many civilian killings,” according to WHO’s head of emergency operations.  Africa News, Aug. 24, 2018.

It’s hard enough to contain Ebola in normal conditions. There is reason for concern that the strategies that eventually worked in West Africa may not be able to stop an epidemic in a conflict zone.

There’s also good news, however: Two of the first ten recipients of the mAb114 treatment have recovered. This is one of five five experimental treatments Congo approved for use in the outbreak that was declared on Aug. 1.  Washington Post, Aug. 25, 2018.

Fully recovered Ebola patients are in general no longer infectious, but there are exceptions.

Isolated cases have long been reported if virus persisting in the eye and in sperm. Now there is a definitive study showing both persistence and active infectiousness in sperm at least 2-1/2 years after recovery, with no reason to think that infectiousness might not continue indefinitely. https://www.sciencesetavenir.fr/sante/ebola-le-sperme-peut-proteger-le-virus-pendant-2-5-ans_125545

From a public health standpoint the sperm of recovered patients is a reservoir from which Ebola disease can re-emerge into the population. This isn’t a huge deal since periodic recurrences were already to be expected from animal reservoirs. It is of concern, however, that outbreaks from sperm infection would likely occur in densely populated areas rather than in the remote jungle villages that are most exposed to wild animals. It also means that countries with no animal reservoirs, and no experience with Ebola, could have outbreaks arising from a visiting or migrating survivor. A sexually active survivor could unknowingly infect multiple partners over an extended period since he himself will not fall ill. Public health agencies need to be vigilant to identify and snuff out any new outbreaks stemming from this source. On the other hand, the lack of such outbreaks so far is somewhat reassuring.

Testing of male survivors might allow concern to be lifted from some and focused on others. Surviving males, unless definitively tested negative, should be strongly encouraged to use condoms. They and their partners should be encouraged to promptly report any suspicious symptoms (though the same pattern of fear and denial is likely to recur in future outbreaks). The right of survivors to medical privacy will be in tension with public health concerns. Survivors known or suspected to be infected could be unfairly ostracized and stigmatized.

Ebola is endemic in the Congo but previously was confined to remote places where it could be rather easily snuffed out. Now it has reached a major city. Cross your fingers that it can be stopped.

Update June 28, 2018: Rapid response and deployment of a new vaccine contained the outbreak, as reported in the New York Times. More than 3,200 people — contacts and health providers — were vaccinated, and none fell ill. As reported in the article, 29 died out of 53 confirmed or probable Ebola cases. This outbreak began in a remote village, presumably from bush meat or other contact with infected wild animals.

It’s relatively easy to think of ways in which things could go wrong, especially when dealing with a deadly disease like Ebola. I’m not optimistic about the likely course of events in West Africa, as you might gather from previous posts. But in this post I want to make an honest effort to envision what success would look like, then work backwards to see how it might be possible to get there from here. What follows is fantasy, but with a serious purpose.

Victory Over Ebola!

It has been 42 days and there have been no new cases in any of the countries affected by the West African epidemic! The last patient has either recovered or, sadly, died. Temporary facilities have been disassembled or burned, and hospital buildings thoroughly disinfected. Everyone has been through a harrowing experience but generous aid and technical assistance from around the world should help the affected countries get back on their feet.

Animal reservoirs of Ebola still exist; it would be wonderful to extinguish the virus worldwide but it’s really hard to imagine that. Ongoing efforts will be needed to discourage contact with infected animals, such as bush meat and fruit that may have been partially eaten by infected bats. Vaccination may reduce the risk of future outbreaks, although it will be difficult to maintain universal immunity in still-poor countries, and a vaccine might not confer immunity against a new strain. So as long as Ebola exists in the wild there will continue to be occasional rural outbreaks. The world obviously must never again let Ebola get out of control!

Mopping Up

The “Effective Reproduction Rate” (Re) [Discussed in The Ebola Chain Reaction] was held down below one, month after month. That is, each person who came down with Ebola infected on average less than one other susceptible person. This was true not only in the aggregate but also in each country and region and neighborhood. The number of patients being cared for peaked, then began a slow but consistent decline, as the number of new patients each day was fewer than the day before. American troops were drawn down, then withdrawn completely, as there was no more need for additional beds.

Winning the War

Gradually, Re was forced lower and lower, down below one and then well below. How was this accomplished? Some combination of these factors:

  1. There were enough Ebola isolation beds for everyone who came down with the disease, in all affected countries, and the public had so much confidence in the care in those facilities that just about everyone who came down with Ebola was admitted to one before other family members were infected. Treatment measures and drugs like ZMapp improved the survival rate somewhat; this reduced suffering and contributed to confidence but didn’t otherwise help bring the epidemic to a stop.
  2. An Ebola vaccine, though not available in sufficient quantities to immunize everyone, was strategically given to American soldiers, healthcare providers and others who were likely to be exposed. Except for President Ellen Johnson Sirleaf and her husband the vaccine was not given out based on money or position.
  3. Infection of healthcare providers was almost completely stopped by:
    1. Universal availability of infection control gear.
    2. Comprehensive training of staff at all healthcare facilities.
    3. Procedures to minimize exposure of unprotected staff during admission or when an admitted patient begins showing Ebola symptoms.
    4. The Ebola vaccine, when it became available.
  4. Traditional funeral and burial practices were suspended by general consent after a massive public information campaign.
  5. People stopped breaking quarantine and/or lying about their Ebola exposure [Discussed in my first post], due to a broad consensus supported by religious and other opinion leaders.
  6. Urban modes of transmission turned out not to be significant, or were greatly reduced by changes in behaviors and other measures.

It would be great if one could imagine the final stage taking place before a vaccine is available, since that won’t be until around the end of the year at the earliest. Please comment if you think I’m too pessimistic, but I just don’t see how you get Re down below one in Liberia and Sierra Leone without a vaccine. Guinea is different, since their problem in recent weeks has been rural flare-ups due to infected citizens returning there from the other two countries. If Guinea can keep snuffing out these outbreaks — using the classic techniques of isolation, contact-tracing and monitoring —  it might be able to get its part of the epidemic under control before the vaccine arrives.

Boots on the Ground

President Obama announced his plan to send 3,000 U.S. troops to Monrovia on September 16, 2014. [CNN 9/16/14] The troops were outfitted and trained in record time and arrived in Monrovia on [wildly hopeful] October 16, 2014. At that time Monrovia needed [a wildly optimistic guess] 1,000 additional beds to accommodate all current Ebola sufferers. The troops set to work building facilities for 1,700 beds, which became ready for patients between [optimistically] November 1 and November 16. By then all the beds were needed, and new patients kept seeking treatment at an increasing rate since Re was still over one. The U.S. identified the problem early and built another 1,700 beds (and trained all necessary staff), also in record time. This time around they got ahead of the curve and Monrovia was finally able to offer isolated care to all Ebola sufferers.

This was the most difficult period of the epidemic, when cases were still growing exponentially, and civil order was progressively undermined. The arrival of Americans had a wonderful effect on the public mood, however. American know-how and money ensured the provision of reliable water, electricity, trash removal and in particular food supplies.While there were a few situations in which small mobs gathered around American installations it was never necessary for a U.S. serviceman to file a single shot, and nobody was injured.

Due to their excellent training and high discipline, only a handful of U.S. troops became infected with Ebola. Those who did fall ill were medevaced back to the U.S., where a combination of excellent care and their own fitness led to a much lower mortality rate than experienced in Africa. Political blow-back from these Ebola casualties was muted due to a national consensus that American needed to do whatever it could to help with the humanitarian crisis in Western Africa. Once the vaccine became available U.S. troops were protected against Ebola and this problem stopped.

Meanwhile, home care kits that had been sent to rural areas proved helpful in reducing Re somewhat, but the key to success in those areas was the addition of more beds, in this case provided and staffed by Médecins Sans Frontières.

The African Union played the same role in Sierra Leone as the U.S. did in Liberia, with the same happy effects. (This strains credulity. The U.S. may have to do the same thing in Sierra Leone itself, which will be exponentially harder the longer it is delayed.)

Guinea continued to experience flare-ups due to travelers from Liberia and Sierra Leone, but it was able to snuff each of them out, and prevent the disease from getting established in its cities.

And They Lived Happily Ever After

Is this a fairy tale or can it happen? There are a lot of ways in which it could fail. To mention just a few:

  • Every day counts when you’re battling an exponentially-growing problem. Any delay in any part of the process risks the numbers growing beyond anyone’s ability to manage them. Liberia may already be beyond the point of no return, but we’ll never know if we don’t try.
  • Sierra Leone is about as bad off as Liberia. Is someone else really going to step in there, or does the U.S. have to go there as well?
  • Political support for the U.S. intervention is likely to be tepid at the outset and could turn sharply against the project after there are casualties. This could force an early withdrawal even if the program seems to be working.
  • There could be a further breakdown of civic order that would make it impossible to get the situation under control.
  • Mistrust and rumor, or arrogance and privilege, could sabotage the program.

The scenario certainly could fail, but it might just work. We must hope against hope that it will succeed.