The End of Ebola in Liberia?

As the media reports the purported “end of Ebola” in Liberia, some caution may be warranted. Liberia’s Ebola case count statistics are highly unusual:

Saturday marks 42 days since Liberia’s last Ebola case -- the benchmark used to declare the outbreak over because it represents two incubation periods of 21 days for new cases to emerge. The World Health Organization [WHO] on Saturday called the milestone a ‘monumental achievement for a country that reported the highest number of deaths in the largest, longest, and most complex outbreak since Ebola first emerged in 1976.’

The politics surrounding the Ebola outbreak are intense – and it is exactly for that reason we need to keep a far more critical eye on what is really going on.

The Centers for Disease Control (CDC) maintains a website keeping track of cumulative Ebola cases (using WHO data) in Liberia, Sierra Leone, and Guinea. From this CDC/WHO data, it is clear that there have been a large number of reported cases during the last six weeks. Actually, there have been 962 new cases of Ebola in Liberia since the March 25 situation report. But this is where we need to distinguish between suspected, probable, and confirmed cases. The CDC data sums all three categories.

WHO is reporting that there has been no confirmed Ebola case since the week of March 22, and “the last confirmed case in Liberia died on 27 March and was buried on 28 March.” This would indicate that the 1,000 suspected and probable cases of Ebola reported in Liberia since March 22 were all false positives. Given the track record of the disease in West Africa, that seems like an extraordinarily high ratio.

As of the March 25 situation report, Liberia had seen a cumulative total of 3,151 confirmed Ebola cases, 1,879 probable cases, and 4,572 suspected cases -- for a total of 9,602 cases and 4,301 deaths from Ebola.

Fast forward to the latest May 6 situation report, and Liberia still has a cumulative total of 3,151 confirmed cases, still has 1,879 probable cases, while the number of suspected cases has increased by 962 up to 5,534 -- for a total of 10,564 cases and 4,716 deaths from Ebola. Two conclusions are apparent: (1) all 962 cases of Ebola since the week of March 22 are suspected; and (2) 415 Ebola deaths have apparently occurred since March 22 despite the fact that “the last confirmed case in Liberia died on 27 March and was buried on 28 March.”

As for the second point, perhaps these are all individuals who lived a particularly long time (i.e., at least six weeks) with Ebola before dying? This would seem unusual since we know that “[p]atients with fatal disease die typically during days six to 16, usually of hypovolemic shock and multi-system organ failure.” Alternatively, these deaths could be historical “reassignments” from non-Ebola deaths to Ebola deaths, but the information to resolve this discrepancy does not appear to be readily available.

What is equally unusual is that the WHO (and the mainstream media) reports that Liberia has had 3,151 confirmed cases of Ebola, but that 4,716 people have died from Ebola. How can an individual be a death from Ebola without being a confirmed case of Ebola? The deaths from Ebola in Liberia are 50 percent higher than the confirmed cases of Ebola in this country.

Compare that to Guinea, where there are 25 percent fewer total deaths from Ebola than there are confirmed cases of Ebola. And in Sierra Leone, there are 55 percent fewer deaths from Ebola than there are confirmed cases of Ebola. In other words, the exact opposite trends as what is being reported in Liberia.

The WHO does include the following caveat on its data: “Data are based on official information reported by ministries of health.” This should raise serious concerns for these three nations, since they are all authoritarian regimes with high levels of corruption and minimal press freedom. In other words, we shouldn’t trust this data at all.

The high percentage of probable and suspected Ebola cases in Liberia to date also contrasts sharply with what is reported out of Sierra Leone and Guinea. More than 70 percent of Liberia’s total Ebola cases to date have been placed in the probable and suspected categories. In Sierra Leone and Guinea, the corresponding numbers are just 31 percent and 12 percent, respectively. Another large red data integrity flag goes up.

As I’ve noted previously, the time-trend for Ebola cases in Liberia is also highly unusual compared to these neighboring countries, and this anomalous trend continues up to the present. Sierra Leone and Guinea have classic sigmoidal cumulative case counts over time. Liberia does not -- its trend was initially the first half of a sigmoidal curve, but then this was followed by a large step-jump in cases, and since late 2014 the trend has been linear. What explains this behavior compared to its West African counterparts?

Up to March 22, one-third of all total suspected, probable, and confirmed cases of Ebola in Liberia were confirmed cases. During the past six weeks, this percentage has magically dropped to zero -- with no new confirmed cases but an additional 1,000 suspected cases. That is a very odd “tipping point.”

Is Ebola really over in Liberia? It is difficult to say, but even a cursory examination of the WHO’s data should cause concern about what is really going on there. Given the political and socio-economic pressures for a nation to be declared “Ebola free,” especially when coupled to scathing criticism over the WHO’s Ebola response and its desire for positive public relations on this file, some healthy skepticism is in order.