Mar 2, 2015

How Did Liberia Escape Ebola?

In August last year Liberia's situation was desperate, seemingly almost hopeless. Ebola was ravaging swathes of the country. Bodies were being dumped in the streets. The country's health system was overwhelmed as doctors and nurses fled their institutions after seeing their colleagues fall victim to the disease. Political leaders abandoned their posts. Societal breakdown loomed as troops were sent in to put down unrest in Monrovia's quarantined slum, West Point (Liberia set to overtake Sierra Leone in Ebola cases.). We looked at them with some pity from Freetown and thought, "Thank God, that's not us."

Today, Liberia is almost free of Ebola. The latest (Feb 25, 2015) WHO update  reveals how far it has progressed. In the week leading up to the update Liberia recorded just one new case of Ebola, whilst its neighbours Guinea and Sierra Leone had a total of 98. What's more, the single case was from a known contact of a previous Ebola patient, and had been under surveillance, meaning precautions were already in place to prevent the further spread of the disease through this patient. American troops, sent in by President Obama last year to help salvage the situation, are completing their withdrawal.

Liberia felt confident enough to recently reopen its borders, after closing them soon after the start of the outbreak. Its schools also recently reopened. Contrast that with Sierra Leone, the worst affected country, where schools remain shut (the government has announced a tentative reopening date at the end of March, but this is dependent on substantial improvemnet in the Ebola picture) and in the latest week 63 new cases were reported, scattered across the country. Even worse, in Sierra Leone, many recent cases have emerged out of the blue, not from contacts who were already under surveillance, meaning there are still unknown chains of transmission snaking through the society. Corpes reported within communities, routinely tested for Ebola, have tested positive, meaning exposure to Ebola for family members and neighbours.

How has Liberia managed this dramatic improvement? A country that, to its Sierra Leone neighbours at least, is renowned for a happy-go-lucky, carefree lifestyle, without a great attention to detail or learning. How has it managed to so clearly outperform its supposedly more serious neighbours?  Has it simply been good luck and nothing more? Has it been a latent or previously unappreciated streak of seriousness and efficiency not present in its neighbours? Has it been the presence of the Americans?

The US government, in September of last year, when the epidemic was at its height in Liberia, rather curiously decided to send a large consignment of US troops to assist in the fight. Why exactly it was felt that troops were needed, as opposed to medics, and what exactly these troops would be doing, was and to a certain extent still is unclear. It was made clear that the troops would not be directly involved in the treatment of Ebola patients. The official line was that the troops were needed to construct treatment centers, to set up labs, to assist in logistics and to train medical workers in the use of Personal Protective Equipment. These would not appear to be tasks for which the US military is uniquely qualified.

Whatever the reasons for the decision, what can not be denied is that a dramatic improvement in Liberia's situation began within weeks of their arrival. By November, the WHO was reporting  that Liberia, which some previous estimates had predicted would have more than a million new infections by the end of the year, appeared to have passed the peak of the outbreak, with declining numbers of new cases. Early in 2015, Liberia reported that only a handful of Ebola patients remained in its treatment centers. By February, it felt confident enough to send three ambulances and a team of experts to assist Sierra Leone in its battle with Ebola.

Meanwhile, the US military has pulled out of Liberia, just as quickly as it went in.  Major-General Darryl Williams, head of the little-known USARAF, described as the US army in Africa, told reporters (Civilians ready to take over Ebola fight: US army) that the US military contingent in Liberia was ready to ".transition to civilian control." The commander was speaking at a conference of the US miliary and  military representatives from 36 African countries held in Senegal from February 9 - 13 this year. The conference, to all intents and purposes unrelated to the American mission in Liberia, provided a convenient backdrop for the US military to showcase its success in the country.

What else might be responsible for Liberia's remarkable recovery in its battle with Ebola?

A look at the key performance indicators given by WHO in its situation reports over the months reveals similar performance in most key indicators from all three countries. When one compares case fatality rates or the numbers of treatment center beds, labs or trained burial teams, there is little difference between Liberia's indicators and those of the other two. From the most recent data, Liberia may be conducting fewer unsafe burials than the other two, although the source of this data, apparently relying on reports received from communities, is uncertain.  However when one looks at the number of contacts listed per new case one does see a marked difference in the numbers between the threee countries. From the first date WHO tracks this indicator by country (WHO Situation Report 26 Nov) Liberia records far higher contacts traced than either Sierra Leone or Guinea: "On average, 6 contacts were listed per new case in Guinea during the past week, 21 in Liberia, and 6 in Sierra Leone. These numbers are relatively low..." The pattern continues over the next several months as Liberia's weekly new cases plummet. For the Situation Report of 14 Jan: "On average, during the past 21 days, 14 contacts were listed per new confirmed case in Guinea, 43 in Liberia, and 11 in Sierra Leone." The trend is consistent throughout, with Liberia way out in front and Sierra Leone bringing up the rear.

On average, then, Liberia has been tracing  3 to 4 times as many contacts per new case as Guinea or Sierra Leone. Could this be the key difference that accounts for Liberia's more successful effort? How they were able to achieve this in populations with broadly similar characteristics is unclear, but the experts have told us from day one that a thorough contact tracing programme is key to the elimination of Ebola. Defeating Ebola, then, as the experts and past experience (What Can We Learn from the Uganda Experience?) have told us all along is not so much a question of sophisticated equipment and advanced medicines and vaccines (although of course these make a difference), not so much a question of doctors and treatment centers, but more a question of applying simple, organized, thorough foot soldiers to trace contacts of known Ebola patients, track them on a daily basis and isolate them if they fall ill. This is what Liberia appears to have done so well.