Dr Ernest Bai Koroma, the President of the Republic of Sierra Leone, was having trouble ‘getting to zero’, and his underlings were getting antsy. “We need one more push,” said Major Palo Conteh, the commander of Sierra Leone’s National Ebola Response Centre (NERC) and a former Olympic quarter miler. “It’s like in the 400 metres when you’re 20m from the finish line, that’s the time to kick hard.”
Brigadier General David Taluva, a jovial officer with the physique of a shot putter, had other ideas. “Perhaps we should quarantine Port Loko,” he mused to a group of officers gathered outside a Portakabin by the Special Court building in Freetown, now transformed into an Ebola situation room. “No, wait, then we would have to quarantine the whole country.”
The officers shuffled their feet awkwardly, then parted to make way for an official late for that evening’s briefing.Newsletter:
Taluva was joking, but of course Ebola is no laughing matter. Port Loko is one of the most populous districts in Sierra Leone and the site of Lungi International Airport. Quarantine Port Loko and you effectively cut the flow of international health workers and aid to President Koroma’s beleaguered administration. The problem is that Port Loko, or to be more precise, Lokomasama – the district to the north of Freetown – is scored with shallow swamps and twisting rivers perfect for evading the Ebola control measures. And, since February, that is exactly what fishermen and recalcitrant villagers in Lokomasama have been doing. The result has been new clusters of infection up and down the country, frustrating the effort to ‘get to zero’, as the World Health Organization (WHO) calls the elimination of Ebola transmissions (getting to zero requires no new cases to be reported in a country for 42 days, double the maximum incubation period of the virus).
“I fear that people have grown complacent,” sighed Professor Monty Jones, the president’s Special Adviser, when I caught up with him in early March at the State House, an imposing stone building with uninterrupted views over Freetown to Susan’s Bay and Destruction Bay. “The epidemic has been going on too long. They just want life to return to normal.”
It was a refrain I was to hear again and again during an 11-day tour of the country that took me from the sun-kissed beaches of Aberdeen – where during daylight hours fishermen reel in glistening barracudas and pots stuffed with outsized lobsters – to a surreal meeting of tribal chiefs and frustrated British officials at Port Loko, to an overgrown graveyard in Kenema, the district in the far east of the country where Ebola first erupted in Sierra Leone in May 2014. On the way I met traumatised survivors, inspiring community activists and stressed-out scientists doing their best to launch trials of experimental vaccines and drugs in difficult conditions.
Everyone I spoke to seemed to have the best interests of the Sierra Leonean people at heart: after all, Ebola is one of the deadliest diseases in nature – a ‘molecular shark’ according to The Hot Zone author Richard Preston. Who wouldn’t want to tame the beast and find a cure to make the fear go away? But while there was no doubting the humanitarian motivations of the international responders, I could not help feel that Sierra Leoneans were now passengers and that it was global health policy makers who were in the driving seat. And as my car sped towards ground zero of the epidemic, a terrible thought nagged at me: Had Sierra Leone exchanged one form of terror for another?
In 1959 the French microbiologist René Dubos warned that for all that vaccines and therapeutic drugs had neutralised many of the microbial threats of the past, the attempt to eliminate infectious disease was a ‘mirage’. This, he argued, was not only because microbes are part of the environment and part of our ecology, but also because radical public health measures that aimed to destroy germs all too often failed to take account of social factors and the wider economic and environmental context. This was particularly true in ‘underdeveloped countries’, where Dubos thought such interventions were “bound to bring about biological disturbances and to give rise to new population problems before there [had] been time for achieving compensatory changes in the rest of the environment”.
Dubos was writing in a period when most of the infectious disease scourges of the past, from cholera to tuberculosis to polio, had been or were at the point of being overcome thanks to vaccines, antibiotics and better public hygiene, and his public health colleagues – with a few honourable exceptions – were no more receptive to his message then than they are today. Moreover, by 1980, with WHO’s declaration that it had eliminated smallpox, Dubos’s message looked positively redundant. Initiated by WHO in 1967, the drive against smallpox led to the first and, to date, only time that the deployment of a vaccine, coupled with rigorous epidemiological contact tracing, has culminated in a zero transmission state. Despite similarly Herculean efforts, albeit in the absence of a vaccine, this never happened with malaria, and since the 1980s we have seen the emergence of a series of new infectious disease threats, from HIV to SARS, bird flu and MERS, as well as the re-emergence of old diseases such as polio.
Nevertheless, WHO and its global partners cling fast to the ‘getting to zero’ mantra – the current international theme for World AIDS Day, for instance, is also ‘getting to zero’, which UNAIDS defines as “zero new HIV infections, zero discrimination and zero AIDS-related deaths”. The zero campaign against Ebola, announced by World Bank president Jim Yong Kim in December, is similarly ambitious, though in this case there is, as yet, no drug or vaccine that can guarantee zero deaths. Zero transmission of Ebola is theoretically achievable, however. Indeed, it is argued nothing less will do, and that unless and until the last case is found and safely isolated, there will always be a threat of Ebola rebounding. That is surely right. The question is, at what cost will containment be achieved?
© Parkin Parkin
A major exporter of diamonds and iron ore, Sierra Leone is rich in natural resources and until Ebola had one of the fastest growing economies in the world. Now mechanical diggers lie idle beside the red African earth, and investment from China and other foreign sources has stalled. Even so, landing at Lungi Airport within sight of fishing skiffs riding the majestic Atlantic breakers, I was reminded that Sierra Leone was once a popular tourist destination: the airport is just metres from a gorgeous sandy beach, and it was just a few miles from here that in the 1980s Mars filmed its famous advertisement for Bounty, ‘A Taste of Paradise’.
That image was all but erased by the country’s brutal 11-year civil war, which only ended in 2002 when British troops helped expel rebel forces from the outskirts of Freetown. Then came a second blow: Ebola.
One of the tragedies of the outbreak in Sierra Leone is that it might have been avoided had WHO acted more decisively at the beginning of the epidemic. The first official acknowledgment of Ebola came on 23 March 2014 when WHO was notified of 49 cases and 29 deaths in Guéckédou, a small village bordering a forested area of southern Guinea inhabited by wild bats, the presumed reservoir of the virus. Within a week Médecins Sans Frontières (MSF) was reporting an epidemic of ‘unprecedented’ magnitude and the spread of infections to Liberia. Kailahun, Sierra Leone’s most easterly province, which shares a border with both Guinea and Liberia, was the obvious next port of call for the virus. Indeed, in April, Dr Sheik Humarr Khan, the chief physician on the Lassa fever ward at Kenema Hospital, who at the time had the only laboratory in the country capable of testing for Ebola, began warning nurses that Ebola was ‘coming’ and they had better be ready. But by the time Dr Khan confirmed the first positive blood sample on 24 May, from a nurse who had attended the funeral of a traditional healer in Koindu in northern Kailahun, it was too late: staff had already admitted a pregnant woman infected with Ebola to the maternity ward. Within days the ward was overrun with Ebola cases, the majority of them other funeral goers or their contacts. In all, ten staff would die battling the virus between May and August, including Dr Khan and the hospital’s chief nurse, Mbalu Fonnie.
Kailahun was Sierra Leone’s ‘shark in the water’ moment. Knowing that a deadly predator had strayed into its territory, the Ministry of Health should have closed the road between Koindu and Kenema and flooded Kailahun with health workers and contact tracers – epidemiological teams equipped to rapidly trace and isolate infectious patients and their contacts. But at the time Sierra Leone had just 1,000 nurses and midwives for the whole country. Besides, at this stage few of the so-called experts, including WHO, seemed to think there was a danger of Ebola reaching a major town or city – and those WHO officials in Geneva who did see the danger thought an international health alert would be counterproductive, stoking needless fear and hysteria at a time when the agency was already overstretched fighting polio and MERS in the Middle East, and when what the world needed was calm. As Dr Oliver Johnson from King’s College London, who had arrived in Sierra Leone the year before to set up a health partnership with Freetown’s Connaught Hospital, told me: “Everyone was saying there had never been a major urban outbreak of Ebola before and that no country in Africa was better prepared to cope than Sierra Leone. The feeling was ‘We’ve dodged a bullet, everything’s going to be fine.’”
But, of course, everything was not fine. To date there have been 12,223 Ebola cases in Sierra Leone – more than any other country in West Africa – and though Liberia has suffered more fatalities (4,486 to Sierra Leone’s 3,865), in Liberia the epidemic peaked in mid-September, whereas in Sierra Leone infections climbed steadily throughout the autumn before peaking at a much higher level in early December. As new Ebola treatment centres came online and burial squads, backed by an army of international contact tracers and outreach workers, descended on rural communities to promote safe hygiene messages, cases declined, but at the end of January that decline stalled. Since then the Ebola reduction effort has plateaued, with the weekly case totals stuck in the mid-70s for most of February and the mid-50s in March.
At the NERC you will hear many theories as to why getting to zero is proving so difficult. There is little doubt that people are weary of the constant reminders not to touch or wash dead bodies and to report suspicious deaths to the country’s Ebola hotline. However, conspiracy theories also abound – when Ebola first invaded Kenema, it was rumoured the virus was a biowarfare experiment that had originated in Dr Khan’s lab. Now the persistence of infections is taken as evidence that President Koroma is deliberately prolonging the epidemic in order to keep international aid flowing to his administration. But perhaps the key reason getting to zero is proving such a challenge is people’s resistance to Western biomedical messaging and their belief that they are immune to or somehow exempt from Ebola. “Every single person in Sierra Leone knows about Ebola and how it is transmitted, but some people just do not care,” said Professor Jones. “They do not think Ebola will affect them.”
© Parkin Parkin
To get a measure of the challenges facing President Koroma on what many officials are calling the ‘bumpy road to zero’, I headed to Port Loko, where the coordinator of the local District Ebola Response Centre, Raymond Kabia, had called a meeting of the district’s 12 political leaders, known as paramount chiefs, in order to address the continued flouting of quarantine measures and restrictions on ‘unsafe’ burials. The idea was to get the chiefs to take ‘ownership’ of Ebola control, but as we sped through unattended checkpoints and past banners scrawled with fading Krio messages (“Ebola nor touch am” – “Ebola don’t touch”), the auguries were not good. A few weeks earlier, a fisherman from Lokomasama infected with the virus had ignored the official requirement to report to an Ebola assessment unit, and instead had persuaded three friends to ferry him to a remote island in the Rhombe swamps. There he consulted a traditional healer before continuing along Port Loko’s mosquito-infested coast to Freetown, where he alighted at a wharf in Aberdeen, a stone’s throw from the Radisson Blu Mammy Yoko, the city’s premier hotel, then host to more than 50 staff from the US Centers for Disease Control and Prevention (CDC).
By now the fisherman was a walking virus bomb, and on disembarking made straight for an Oxfam-built toilet block, where he vomited haemorrhagic fluids. As a result, 20 villagers in the Tamba Kula district of Aberdeen were also infected with Ebola, prompting the quarantining of the community for 21 days. In theory that should have been the end of the transmission chain, but despite the best efforts of contact tracers one of the contacts got away, hitching a ride on the back of a motorcycle to Makeni, three hours from Freetown, where he infected three more people, including a traditional healer. All four were now being ‘offered’ life-saving treatment at an Ebola treatment centre in Makeni operated by the International Medical Corps (IMC). I say offered because, according to a nurse from Public Health England I spoke to, several patients were refusing treatment, fearing IMC medical staff were trying to murder them with what the healer, who has been keeping up a running commentary on the ward, calls their ‘Ebola guns’ – the hand-held electronic thermometers that nurses use to record patients’ temperatures.
For Kabia, a former North American fundraiser for President Koroma’s All People’s Congress party, such beliefs are par for the course in Sierra Leone. Sitting in his office at the end of a low bungalow, Kabia could be mistaken for any middle manager shuffling papers and barking orders. He explained that in an effort to crack down on Ebola refuseniks he had banned night-time fishing in Lokomasama and instituted regular temperature checks on foot passengers at Barlo Wharf, the main ferry point for Freetown. He’d also instructed harbour masters to keep a look out for fishermen slipping ashore in barges under cover of darkness. But for the main he depended on the good will of the paramount chiefs and their section heads. In Kailahun, Kenema and Bo this method had proved successful, with chiefs using their authority to ensure that village headmen reported the arrival of suspicious visitors promptly to the authorities. But in Port Loko, headmen had been actively concealing Ebola patients from the authorities and turning a blind eye to secret burials. As a result, epidemics had flared in villages where Kabia thought he had an accurate head count and there was no risk of further outbreaks. “So far we have sacked ten section chiefs and ten village headmen and fined them over 500,000 leones [about $100] each, but nothing seems to work,” he lamented. “We don’t know what more we can do. The government and international partners have provided everything for this district.”
Inside the response centre, the control room was already heaving with UK Department for International Development (DFID) and WHO officials. Two rows of desks had been set aside for the paramount chiefs near the front, the better to view the presentations. As the chiefs, dressed for the most part in traditional African robes, took up their places, the air of expectation mounted. The commander of the control room – a well-built DFID official whose name I didn’t catch – was clearly hoping to inspire the chiefs with a tub-thumping speech, but the wind was rather knocked from his sails when he realised he would have to pause between phrases for the Krio translator.
“When I took up this post I made a promise to you that we would isolate the sick within 24 hours and give them a safe and dignified burial [pause]. We have done that, but I’m sorry to say we are not at zero yet, we are not even close [pause]. There is nothing more that I and my colleagues in this control room can do [pause]. We are looking to you – the paramount chiefs – to lead the next stage of this fight.” The official ended his oration with a proverb: ‘Cometh the hour, cometh the man.’ “This is the hour and you are the men,” he declared. But though familiar to the Englishmen in the room, the proverb did not translate well, and the applause was muted.
Thankfully, in the next presentation the numbers told their own story: 1,393 confirmed Ebola cases in Port Loko since the epidemic had begun, a total exceeded only by the Western Area (3,270). A WHO epidemiologist flashed up a flow chart showing a typical transmission chain. The lines were linked by coloured blobs marked ‘SB’, ‘HM’ and ‘TH’ – WHO code for ‘secret burial’, ‘headman’ and ‘traditional healer’. The idea, presumably, was to draw attention to entrenched behaviours and practices that, in the official’s opinion, were continuing to fuel disease clusters. If so, his message backfired – or, perhaps, the chiefs grasped its coercive intent better than he did. “We should flog them,” declared Bai Lamina Ngbathor II, the paramount chief of Lokomasama. “Believe me, if we flog these people they will not do it again.”
Other chiefs were more concerned about the situation of Ebola convalescents (people who had survived Ebola). The government had recently launched a campaign warning that the virus can persist in semen for up to 90 days after recovery. “How are we supposed to stop people from having sex?” asked one chief entirely reasonably. “You need to keep them in the Ebola holding centres for longer.”
In response, the DFID official mumbled something about a ‘condom distribution’ plan, but the meeting had clearly veered way off script. It was hard to resist the conclusion that the chiefs understood the hygiene issues perfectly and were now exposing the flaws in the public health messaging. Similar criticisms could be levelled at the NERC’s standard operating procedures for burials. These require that deaths are reported promptly to the authorities so that people can be buried in a ‘safe and dignified’ manner within 24 hours. But as a social anthropologist who had been studying the burial teams for some time told me: “The teams are not as safe and dignified as the NERC and their partners would have us believe. Some are the problem rather than the solution. Burials have become a lucrative business.” The result is that in some parts of the country people have been refusing to cooperate with the burial squads or exhuming the bodies of Ebola victims and reburying them in accordance with local traditions, infecting themselves and others in the process.
For all that these behaviours may be frustrating international efforts to get to zero, Sierra Leone’s bumpy road also represents an opportunity for scientists. One of the paradoxes of Ebola control is the less you are able to reduce transmission, the more patients there are available for vaccine trials and drug studies. In this respect, contact tracing and biomedical interventions that aim at improving treatment outcomes are antagonistic. However, to the extent that both depend on the mobilisation of the same technological resources – principally, laboratories and rapid ways of diagnosing the disease – the interests of contact tracers and those enrolling patients in trials coincide.
This April the CDC and Sierra Leone’s College of Medicine hope to begin recruiting for a trial of a recombinant vector vaccine that uses a vesicular stomatitis virus (VSV) to deliver glycoproteins from Ebola Zaire, the strain currently circulating in West Africa. Developed by NewLink Genetics, Merck and the US National Institutes of Health, the plan is to enrol between 6,000 to 8,000 health workers in the Western Area and Bombali. Instead of a classic placebo control arm, the CDC will recruit subjects on rolling basis, meaning that some will receive the vaccine ahead of others, thereby generating robust data while meeting ethical concerns that every trial participant should be offered the same protection.
Close on the CDC’s heels is a team from the London School of Hygiene & Tropical Medicine, which is in negotiations to test a prime-boost vaccine developed by Janssen, a Belgian subsidiary of Johnson & Johnson, that combines proteins from three strains of Ebola, plus the Marburg virus. The first part of the vaccine aims to ‘prime’ the immune system; the second part, acts as the ‘boost’. The team would seek to recruit 40 volunteers at first, rising to 400, but in different districts of Sierra Leone to the CDC trial. If all goes well, it would then offer the vaccine more widely. Finally, a team from the University of Oxford has just launched a phase II study of an experimental drug, TKM-Ebola, at a Danish-run treatment centre in Port Loko. Developed by Tekmira Pharmaceuticals, TKM-Ebola works by blocking the genes that control viral replication and has proved 100 per cent effective in non-human primates. As of 20 March, four patients had been enrolled.
One of the advantages of the Oxford study is that, unlike a vaccine trial, there is no need for a control group: patients are recruited until such time as the intervention is shown to be successful or it fails, at which point the study is halted. By contrast, the vaccine trials require finding comparable population groups with statistically similar chances of contracting Ebola, a task that becomes harder as case numbers fall and when social and cultural behaviours in some populations produce clusters of infection that are not random at all.
In an ideal world an effective vaccine or drug would be a win–win situation, persuading people that the conspiracy theories are wrong and that it makes sense to comply with the government’s Ebola regulations. But in a world in which between half and 70 per cent of those entering Ebola treatment units do not come out alive and international health workers are mysteriously airlifted to the USA and the UK for life-saving treatment, where they enjoy much better clinical outcomes, it is little wonder suspicion persists. “The people in these populations know something that you don’t,” explains Dr Armand Sprecher, an emergency physician with MSF and a veteran of several Ebola outbreaks. “We, MSF, are brought there at the behest of political organisations that do not always help keep the best interests of the rural African community at mind.” In short, Dr Sprecher argues, the West has a marketing problem: “We get off on the wrong foot pretty much in each and every outbreak.”
If so, the only way to get to zero may be to get onto the right foot, and quickly. After a poor start, progress is now being made in community engagement through the efforts of organisations like UNMEER (the UN Mission for Emergency Ebola Response) and charities like Restless Development and Street Child. The result is that in many districts of Sierra Leone trust has been restored and there have been no new cases of Ebola for several weeks, while Liberia recorded no cases anywhere in the country in the first three weeks of March. (Unfortunately, on 21 March it was reported that a 44-year-old woman in Monrovia had been diagnosed with Ebola, most likely as a result of sexual contact, forcing WHO to reset the clock on Liberia’s countdown to zero.)
The fact is that without a vaccine or treatment, getting to zero is probably going to require ever more coercive measures, but coercion is an imperfect science, and fishermen will always find a way to slip the net. Either way, it’s bad news for research scientists. As Dr Sprecher puts it, the best response to the West’s marketing problem is to produce ‘good advocates’, survivors who can bear witness to what happens inside treatment units, but “in order to have survivors you need patients and in order to get patients you need survivors”. In other words, it’s a catch-22.
© Parkin Parkin
The further you go from Freetown, the fewer Ebola patients you encounter. On the outskirts of Bo we passed a huge MSF Ebola management centre, deserted save for a few orderlies and a skeleton medical staff, and in Kenema it was the same. Except for the triage tents at the entrance to the hospital, you would never know Ebola had once cut a swathe through the maternity ward here, bringing misery to a place of life. But while Ebola has now returned to the forest, Dr Khan’s Lassa fever unit remains open for business. Kenema’s diamond mines are a breeding ground for rats, the carriers of Lassa, and technicians have been processing and storing Lassa blood samples here for several years. Those stores are proving to be a serological goldmine: retrospective studies by Tulane University researchers using Ebola reagents have revealed antibodies in the blood of several ‘Lassa’ patients. The first of these seropositive Ebola samples dates back to 2006. In other words, Ebola may have visited Kenema before but no one noticed. “The scientific question for us now is why that didn’t turn into an outbreak”, said Dr Joseph Fair, a Lassa expert and US Army Researcher from USAMRIID who helped set up Kenema’s diagnostics platform.
Answering that question will require not only a better understanding of the ecology and the biology of the virus and its interaction with the immune system, but also what Dubos would have called ‘social and environmental factors’. As Dr Fair recalled: “When I first came to Kenema in 2006 there was no Chinese highway, just a dirt road, and the journey from Freetown took eight hours. Now, it takes three, and instead of jungle all you see are cassava fields. That’s got to have had an effect.”
© Parkin Parkin
One of the reasons Ebola has proved so difficult to eradicate in Sierra Leone is the attachment to traditional burial customs. These dictate that the families of the deceased should be able to kiss and wash the bodies of their loved ones before laying them to the rest. But, of course, such customs also risk spreading the virus further, and in an effort to get to zero the NERC has mandated that the bodies of victims be disposed of within 24 hours – an edict that, in the case of the Western Area, usually means interment in a hastily dug grave in Freetown’s King Tom cemetery. At Kenema’s Dama Road cemetery, however, perhaps because it is further from the centre, the rules were not applied so strictly and people had time to place markers on the last resting place of the nurses and technicians who were among Ebola’s first victims. On a broiling hot afternoon in March I asked Mohamed Sow, a driver with the Tulane Lassa fever programme, to take me there. Sow did not need to ask directions: when Ebola struck it was all hands to the pumps, and instead of ferrying Lassa patients to the hospital he found himself transporting victims of Ebola, many of them former colleagues, to the cemetery.
Unlike at King Tom, there was no one guarding the gates at Dama Road and no one insisting we submit to a temperature check. We simply parked by the entrance and walked in. Although it had been scarcely nine months since Ebola swept through Kenema, the graves were already overgrown with tropical vegetation. As we picked our way gingerly between the plots, at first it was hard to distinguish one from another. Then we came across a marker commemorating the death of a local pastor. According to Sow, the pastor had contracted Ebola after visiting Kenema’s maternity ward to read the last rites to a patient. He was just 34. “He was a Christian, a man of God, so it was his duty,” Sow told me matter-of-factly. “He could not refuse.”
Soon, we realised, we were standing in a thicket of Ebola graves. The majority had crosses like the pastor’s, but in some cases the names were Muslim and the epitaphs were in Arabic. All seem to have died in a three-month period between July and September 2014. Sow wanted to show us other graves, but by now both my driver and I had seen enough. The earth may have been dry and cracked, but the fear was still palpable: it was the closest we had come to the virus in 11 days.
On the drive back to Freetown neither of us said very much for the first half hour. The highway was empty and, even though we were now speeding toward the epicentre of the epidemic rather than away from it, we were both relieved to be leaving Kenema. Eventually, however, we reached a checkpoint and had to stop to show our credentials and submit to the obligatory temperature check.
“People are sick and tired of Ebola,” said my driver as we pulled away. “Do you think these vaccines will really make a difference?” I replied that I didn’t know, but that scientists had a duty to try, if not for now then for the next time. He paused, considering my words. Then, smiling, he pointed to a phrase painted on the bumper of the bus in front of us. It read: “No condition is permanent.”
Two weeks after my return from Sierra Leone, I learnt that President Koroma had finally bowed to expert advice and ordered a 72-hour nationwide lockdown, stating he would do “whatever it takes” to get to zero. Suddenly, Taluva’s off-the-cuff remark had become official policy. The lockdown lasted from 06.00 on Friday 27 March to 18.00 on Sunday 30 March, imprisoning six million Sierra Leoneans in their homes all weekend. The only people who were exempt were health workers. “We are embarking on active case-finding in all the hotspots in the country,” said Major Conteh. “We understand that people are tired and want to get back to their normal life, but we’re not there yet. It’s the final metres in the race,” said Roeland Monasch, a spokesman for UNICEF. In central Freetown and Lumley Beach Road, where most of the luxury hotels are located, the regulations were by and large observed, but in the dense slums of eastern and central Freetown the lockdown resulted in angry confrontations with police, and tear gas was fired. According to press reports, residents in these areas were hungry and had taken to the streets in search of food.
Following the lockdown Sierra Leone recorded no Ebola cases for several days, raising hopes that it had reached the end of the road to zero. But the hiatus was short-lived, and by the end of the first week of April a new case had appeared in Port Loko, followed, a week later, by eight further cases in Kambia and the Western Area.
Mark Honigsbaum is a Wellcome Trust Research Fellow who has received funding from the Trust for an oral history of the Ebola epidemic.