Initially from early June to mid-September 2014, the outbreak of Ebolavirus disease (EVD) in Guinea, Liberia and Sierra Leone grew exponentially, with national doubling times of between 16 and 30 days. The authors originally predicted a cumulative total of 21,000 cases in these three countries by November 2nd. However, the outbreak changed course in September with the increase in case incidence halting in Guinea and Sierra Leone and reversing in Liberia. The authors examined the epidemiology up to 14th December and found that in the preceding 4 weeks the number of confirmed or probable cases of EVD ranged from 77 to 154 per week in Guinea, 73 to 138 in Liberia, and 327 to 537 in Sierra Leone. By 14th December there had been a total of 18,625 confirmed, probable or suspected cases in eight affected countries (the three mentioned above, plus Mali, Nigeria, Senegal, Spain and the United States), with 6971 deaths. With the scale-up of case isolation and safe burial measures the case reproduction numbers for all three countries have now fallen to 1. Therefore while the worst fears of persistent exponential growth beyond September were not realised, EVD still presents a huge challenge in the coming year in West Africa.
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