Ebola in Graphics: Toll of a Tragedy
THE first reported case in the Ebola outbreak ravaging west Africa dates back to December 2013, in Guéckédou, a forested area of Guinea near the border with Liberia and Sierra Leone. Travellers took it across the border: by late March, Liberia had reported eight suspected cases and Sierra Leone six. By the end of June 759 people had been infected and 467 people had died from the disease, making this the worst ever Ebola outbreak. The numbers keep climbing. As of November 2nd, 13,042 cases and 4,818 deaths had been reported worldwide, the vast majority of them in these same three countries. Many suspect these estimates are badly undercooked.
The rate at which cases give rise to subsequent cases, which epidemiologists call R0, is the key variable in the spread of Ebola. For easily transmitted diseases R0 can be high; for measles it is 18. Ebola is much harder to catch: estimates of R0 in different parts of the outbreak range from 1.5 to 2.2. Although there are some signs that the virus is gradually being brought under control in Guinea and Liberia, any R0 above 1 is bad news. The very high mortality rate of the disease, estimated at 70% in this outbreak, means that Ebola can quickly claim more lives than other, more established killers.
The inadequacies of the health-care systems in the three most-affected countries help to explain how the Ebola outbreak got this far. Spain, which has gone 21 days without a new case following its first locally transmitted case in early October, spends over $3,000 per person at purchasing-power parity on health care; for Sierra Leone, the figure is just under $300. The United States, which suffered its first Ebola fatality on October 8th, has 245 doctors per 100,000 people; Guinea has ten. The particular vulnerability of health-care workers to Ebola is therefore doubly tragic: as of November 2nd there had been 546 cases among medical staff in the three west African countries, and 310 deaths.