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 Violence has been so serious that the CDC has withdrawn three of its Ebola experts to Kinshasa, 1,500 kilometers away.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.

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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.

Great News From Liberia

The news from Liberia is wonderful: the last known Ebola patient has been discharged from treatment! [NYT 3/6/15] This doesn’t make Liberia “Ebola free” – that requires 42 days (twice the incubation period) with no new cases. Many contacts are still being monitored, and others may not have been identified, so Liberia may still have to deal with a few more local outbreaks before it can declare victory. Also, so long as Ebola continues in neighboring countries the disease may be brought back to Liberia by travelers (though note this heartening item about an effective Liberian border control operation: [IOM 2/4/15]). And the risk of an unrelated jump to a human from an animal reservoir will continue indefinitely. Nevertheless, this is a moment to be savored!

Update 3/24/15: A new patient has been identified in Liberia, who probably was infected by her boyfriend, an Ebola survivor. [NYT 3/24/15]. This is disappointing, but the fact that only one instance has come to light suggests that this mode of transmission is rare.

Ongoing Transmission in Sierra Leone and Guinea

Sierra Leone initially showed a similar pattern of precipitous decline in patients, but since the end of January weekly cases have stabilized between 60 and 100. [WHO 3/4/15] This is better than exponential growth, but it’s not on track to ending the epidemic. Guinea didn’t have as sharp a peak, but it also hasn’t experienced such a dramatic improvement: about 50 cases are continuing to arise each week. In both countries the steady rate of new cases implies an Effective Reproduction Rate of about 1. Pushing this down just a little would eventually end the epidemic, while letting it rise would allow exponential growth to resume. Liberia has shown that it’s possible to snuff out the epidemic, but Sierra Leone and Guinea are not yet following in Liberia’s footsteps.

I don’t claim to know how Liberia did it, but somehow the Effective Reproduction Rate dropped to about 1 in September, then fell much lower from October on. Sierra Leone’s peak and fall were similar, but occurred about two months later, and the decline has now leveled out. While the opening of new treatment centers certainly helped in recent months, my own best guess is that the main factor in both countries is that people simply “got religion.” That is, a large enough fraction of Liberians came to accept that Ebola is caused by a virus, not a curse; that people who fall ill need to be cared for in safe settings, rather than at home; and that corpses need to be handled with extreme care. I suppose that a comparable fraction of Sierra Leone’s population reached similar conclusions, but the epidemic is now continuing there and in Guinea within sub groups that haven’t fully accepted the message.

Devilish Details

The last Ebola patient in Liberia, Beatrice Yardolo, came from a worrisome cluster of cases “in a community called St. Paul’s Bridge, located in what was one of the biggest Ebola hot spots in Monrovia, New Kru Town.” [NYT 3/6] The New York Times reported that, “[t]he outbreak was unusually violent and far-reaching, in part because it involved criminal gangs that did not cooperate with the authorities and fears that it could be spread through a knife fight with one member nicknamed Time Bomb.” Even more troubling was the fact that known contacts on several occasions left Monrovia for other parts of the country. [FrontPageAfrica 2/3/15] One of the escaped contacts died in Margibi County, and required the tracking of 256 contacts there. [GNN Liberia 2/4/15]

Ebola came into the Yardolo family from Beatrice’s cousin Steve, who probably became infected at an Ebola treatment center where he worked. [AllAfrica 3/6/15]  Steve infected several other members of the family, eventually including his daughter Amanda. Beatrice took responsibility for Amanda’s care, but again and again Amanda was mis-diagnosed and rejected from Ebola treatment centers. Beatrice was left responsible for bathing and otherwise caring for her. After Amanda died Beatrice went immediately to a treatment center started showing symptoms, which probably saved her life.

Ebola didn’t end in Liberia because people behaved well, but because the strategies of isolation and contact tracing worked despite much bad behavior and many mistakes.

Sierra Leone’s experience is vividly described in another New York Times piece. [NYT 2/18/15] The epidemic was re-ignited by three sick fishermen who landed in a poor area of Freetown in early February. Two dozen people in the area ended up contracting Ebola from this initial group before transmission was brought under control. A quarantine was imposed but was frequently broken. One shopkeeper fell ill but was afraid to go to a hospital in Freetown. Instead he broke quarantine and traveled three hours to his home village, where he visited a traditional healer, then died. He caused the infection of some 42 people in the district.

Endemic Ebola?

Ebola is still being actively transmitted in Sierra Leone and Guinea, and may yet recur in Liberia, or spread to other countries. But the Liberian experience gives every reason to hope that the techniques that worked there can eventually end this epidemic altogether. The possibility must be acknowledged, however, that the epidemic will continue indefinitely, neither growing exponentially nor definitively ending. In this case Ebola would become “endemic” to West Africa — just one of the typical diseases that people get there. I can’t disprove this — indeed it seems to be happening now in Guinea — but I have several reasons for doubting that this will happen with the current strain of Ebola:

  • It’s too deadly. A cluster of a less lethal disease might go relatively unnoticed, but this can’t happen with Ebola. The deaths of family and friends, one after another, cannot be ignored. The presence of Ebola in a community will not be tolerated for long.
  • Its incubation period is too short. A disease that takes months or years to emerge (e.g. AIDS, leprosy, tuberculosis) can hide in a human population, but Ebola emerges quickly, or not at all.
  • It’s only transmitted from person to person. Aside from the wild animal reservoir (discussed below) Ebola appears to be transmitted only from person to person. A disease that could also infect some more familiar animal, like fleas or rats, could hide in the animal reservoir and reemerge unpredictably. Fortunately, Ebola shows no sign of doing this.
  • It’s only transmitted by direct contact. Fortunately, Ebola isn’t airborne; it’s transmitted only by direct contact with bodily fluids or contaminated surfaces. This makes contact tracing and isolation so effective. It’s much more difficult to contain a disease like the flu that spreads through the air.
  • People are infectious only when they are ill.  Update 3/24/15: (except for the semen of male survivors). There is no indication that there are “Typhoid Marys” who can transmit Ebola without themselves falling ill, except for one instance in which a male survivor appears to have infected his partner, presumably through semen, which is known to contain Ebola virus for several months after recovery. [NYT 3/24/15] This will make the disease a bit more difficult to eradicate, but is not cause for panic. As noted above, the fact that just one infection of this type has come to light suggests that this mode of transmission is infrequent. Additionally, now that an example exists one might expect many “discordant couples” (in which the male is a survivor and the female is not) to use condoms, which should further reduce the risk. One question that calls for further research is how long the virus can persist in the semen of a male survivor, and whether a negative semen test is sufficient to make unprotected intercourse safe for the survivor’s partners.

For these reasons I think it’s highly unlikely that Ebola will become endemic based on human-to-human transmission (absent mutation). So long as we don’t lose focus I expect that Sierra Leone, and eventually Guinea, will be able to end this epidemic using the standard techniques of contact tracing, isolation, funeral management and education.

The Wild Animal Reservoir

In one important respect Ebola already is endemic to East Africa: For forty years it has jumped every few years from its wild animal reservoir (probably fruit bats) into a human population. Just this year an unrelated Ebola outbreak in a rural area of Uganda flared briefly and was extinguished. [CDC]  There is every reason to expect this pattern to continue, since:

  1. even when we have a vaccine it will never be feasible to vaccinate the entire relevant population,
  2. contact with infected animals such as bush meat may be reduced through education but can’t be prevented altogether, and
  3. there is no conceivable way to eliminate Ebola from the animal reservoir.

This is too bad, but it’s a bearable situation, since most outbreaks start in remote rural areas, where they can be quickly snuffed out so long as they are detected early and the response is competent and decisive.

So far as we know the West African epidemic arose from a single jump between a wild animal reservoir and a human. There might be some reason why this was an isolated incident that won’t recur. But it seems much more likely that Ebola is now established in a West African animal reservoir, from which it will now jump periodically into humans, the same way it has for decades in East Africa. After the current epidemic is brought under control it will be essential for all West African countries to establish systems for early detection of new Ebola outbreaks, as has long been the case in East Africa.

We’re lucky that infective contacts between humans and the wild animal reservoir are so rare. If Ebola became established in an animal population that lived in closer contact with humans — rats, pigs, or even dogs — animal-human transmissions could be much more frequent. There is no evidence, however, that this is happening. Genetic evidence continues to indicate that the entire West African epidemic was sparked by a single animal-human transmission in Guinea, from a bat to a 2-year-old boy.

There are still great challenges and great dangers — more on that later — but the big news is the abatement of the epidemic in Liberia.

Miracle in Liberia

Here is WHO’s chart of new cases in the country as a whole, and in the Montserrado district (which includes the capital, Monrovia). [WHO Current Ebola Situation Report]

Liberia_New_Cases_20141203

The drop, starting in mid-September, is breathtaking, even when figures from the patient database are adjusted by more realistic situation reports. There is now a big oversupply of isolation beds in Monrovia, and in some other parts of the country. The ready availability of beds certainly contributed to the drop in new cases, but other factors must also be at work since the fall began while all available beds were still occupied. I speculated on the reasons for the apparent drop in my previous post: Too Good to be True? I don’t have much to add, except that behavior must have dramatically changed in Liberia. Changing people’s behavior is very hard, especially when it relates to deeply-rooted cultural norms such as caring for loved ones and religiously-mandated burial practices. The message from Liberia is that behavior change is possible, and it can stop Ebola (in its current form) in its tracks.

The magnitude of the change is dramatic. The Reproduction Rate (defined in The Ebola Chain Reaction) for Liberia had been estimated in September at 1.51 [NEJM 9/23/14] , which is consistent with the left half of the charts shown above — exponential growth. The right half of these curves implies a Reproduction Rate far below the steady state of 1.0, which means that the rate dropped by at least a factor of two in a period of just a few weeks. It’s marvelous that such a large change was possible in such a short time frame. This affords a solid basis to hope that the same can be accomplished in the other affected countries.

The epidemic is by no means over in Liberia! We must not let down our guard, or infection rates could jump up again. But we can certainly take heart. It might also be reasonable to mothball the construction of new isolation facilities in Monrovia, keeping open the option of finishing them if they are ever needed. To the extent possible, new facilities should be constructed in Sierra Leone and Guinea, or perhaps under-served parts of Liberia,  rather than in Monrovia.

Steady Rate in Guinea

The rate of new cases jumped dramatically around the end of August and has continued at more or less the same level. This is a continuing severe epidemic, with Reproduction Rate around 1, but it is growing slowly if at all.

Guinea_New_Cases_20141203

WHO’s helpful situation report breaks the results down by region and points out a particular vulnerability in the northern area adjacent to Mali, which may lead to further spread to that country.  [WHO Current Ebola Situation Report] This is still a desperate crisis, but the slow rate of growth gives us time to get ahead of the situation. And the example of Liberia shows that control is possible.

Exponential Growth in Sierra Leone

The big worry now is Sierra Leone, where the rate of new cases is continuing to grow exponentially.
Sierra_Leone_New_Cases_20141203

Growth in Sierra Leone is country-wide, but the capital of Freetown presents the most acute problem because it is running out of beds. Once again, the WHO situation report describes what’s happening and the management plan: [WHO Current Ebola Situation Report]  We just have to hope that the miracle in Liberia can be replicated in Sierra Leone.

Concluding Observations

Just a few weeks back Liberia was the greatest worry, and the focus was on building isolation facilities there, especially in Monrovia. Now many of those facilities stand empty. Like a wily prize fighter Ebola ducked the roundhouse punch we had planned for it there, and is continuing to fight in other parts of the ring. This doesn’t mean that our plans were mistaken, or even unnecessary, since nobody could have foreseen the dramatic drop in transmission in Liberia. But it does mean that we need to be nimble in responding to where the greatest need currently is — Sierra Leone and the northern districts of Guinea. The need to redeploy resources is problematic, since it takes time and effort to design, build and staff a new facility. We have no choice, however: we must follow the epidemic wherever it goes.

So long as there is active transmission we are still exposed to two big risk factors:

  • spread to another country with crowded slums, traditional practices and a weak healthcare system, and
  • mutation to become more contagious.

I’m optimistic at this point that we can control the epidemic before either of these disasters occurs, but the need to end Ebola is still urgent.

 

 

 

 

For months treatment centers in Monrovia have been turning away patients, who are then cared for at home, which places household members at high risk of infection. New treatment facilities have been filled as soon as they become available. Projections showed the need for ever increasing numbers of beds, for at least the next several months.

But suddenly, around the middle of October, reported cases and burials in Monrovia have started to drop. Some Ebola clinics are less than half full! [NYT 10/31/14]  [Economist 11/1/14] Can it be that the epidemic is waning? Or are appearances deceiving? On the same day Yale researchers warn that deaths could skyrocket, consistent with the earlier models of exponential growth. [Yale Daily News 10/31/14]

I don’t have a crystal ball, but I will just throw out a few ideas:

  • Home treatment kits started being distributed around the middle of October. [Reuters 10/20/14] This is a desperate stopgap, since patients become so highly contagious in the last stage of illness that caregivers and others in a household are likely to be infected. But is it possible that many people are using home treatment kits instead of taking patients to clinics? If so, the epidemic could be roaring ahead unnoticed. Except for this: where are the burials? To make sense of this hypothesis you would have to also assume that families were secretly burying their dead members (thus creating more opportunities for infection). While this has been reported it seems implausible that it would occur widely enough to impact statistics, especially in an urban context.
  • More hopefully, the worst Reproduction Rate seen for Ebola in this epidemic was 2.2, which, though ample to fuel exponential growth, is not that much above the steady-state level of 1.0. (See my earlier post for details). Also, transmission of Ebola is a function of human behavior: primarily incautious care-giving and the handling of dead bodies. It’s difficult to change people’s behavior but the crisis in Liberia may just have been sufficiently acute for this to happen. Many individual decisions just may have added up to success: not to touch someone who seems ill; to use a barrier when touch is necessary; to sterilize objects with chlorine bleach; to allow a body to be taken away without traditional cleaning and funeral rites.
  • This report is from Monrovia, the capital of Liberia. We must not lose sight of what’s happening in other parts of Liberia, and in the other countries with active transmission: Guinea, Sierra Leone, and now quite possibly Mali.

Meanwhile, a new 200-bed treatment unit opened on October 31 in Monrovia. This is a big addition to the 500 beds previously available. “The daily management of the treatment centre will be taken care of by the Liberian Ministry of Health and Social Welfare, with support from African Union and Cuban foreign medical teams.” [WHO 10/31/14] I hope it is never needed, and that unused Ebola facilities may perhaps become the nucleus of an improved ongoing healthcare system in these desperately poor countries.

Ebola Resources