[PA Engineer]

The New England Journal of Medicine Article Ebola Virus Disease in West Africa — The First 9 Months of the Epidemic and Forward Projections, provided some interesting insights into the numbers.

The growing numbers of cases reported from Guinea, Liberia, and Sierra Leone in August and early September suggest that the Rt remains above 1 in a still-expanding epidemic (reliable estimates of Rt could be obtained only to early September owing to reporting delays). As of September 14, the doubling time of the epidemic was 15.7 days in Guinea, 23.6 days in Liberia, and 30.2 days in Sierra Leone (Table 2). We estimate that, at the current rate of increase, assuming no changes in control efforts, the cumulative number of confirmed and probable cases by November 2 (the end of week 44 of the epidemic) will be 5740 in Guinea, 9890 in Liberia, and 5000 in Sierra Leone, exceeding 20,000 cases in total (Figure 4FIGURE 4 Observed and Projected Case Incidence. The true case load, including suspected cases and undetected cases, will be higher still.

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We estimate the R 0 to have varied between 1.71 (upper boundary of the 95% confidence interval, 2.01) in Guinea to 2.02 (upper boundary of the 95% confidence interval, 2.26) in Sierra Leone.

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Our estimates of case fatality are consistent in Guinea (70.7%), Liberia (72.3%), and Sierra Leone (69.0%) when estimates are derived with data only for patients with recorded definitive clinical outcomes (1737 patients).

Frankly, I think the numbers are twice the case rate reported in this study.

[Covenantor]

The waterfall effect of determined runners will also increase exponentially. How many more Duncans are already on the way?

[Cvengr]

You probably aren’t too far off. John Hopkins is using a 2.5x error factor of actual to reported cases.