Challenges and opportunities in disease forecasting in outbreak settings: A case study of measles in Lola Prefecture, Guinea

Between January 23 and April 4, 2015 (weeks 4–13 of the year), 284 cases of measles were identified in Lola, a prefecture of approximately 180,000 people in southeast Guinea within the Nzerekore region (Figure 1). Given healthcare system disruptions caused by the Ebola outbreak, there was concern that reductions in measles vaccination may have increased susceptibility in the younger population.1 A supplementary immunization activity, aimed at decreasing measles susceptibility, was planned for Guinea in 2014. However, this campaign was interrupted by the Ebola outbreak and never reached Lola prefecture. In addition, within the Nzerekore region of Guinea, measles vaccination coverage has been relatively low (reaching only 61% of children aged 9–59 months in 20122), suggesting that a large proportion of the population aged less than 5 years was susceptible to a measles outbreak. These factors raised concerns that these 284 reported cases heralded a large and potentially deadly measles outbreak (e.g., the estimated case–fatality ratio of measles cases in Africa was 3.7%).3 Open in a separate window Figure 1. (A) Map of Guinea, with regions outlined and the Nzerekore region highlighted. (B) Zoomed in, we see the number of susceptible individuals in the Nzerekore region of Guinea if a 25% interruption of measles vaccination due to the impact of Ebola on the healthcare system is assumed. Lola prefecture is in the lower right-hand corner of the map and is seen in (C) with labeled subprefectures. The color of each subprefecture coincides with the number of reported measles cases up to week 13 of 2015. This figure appears in color at www.ajtmh.org.