Ebola Virus Epidemiology and Evolution in Nigeria

Folarin, Onikepe A.; Ehichioya, Deborah; Schaffner, Stephen F.; Winnicki, Sarah M.; Wohl, Shirlee; Eromon, Philomena; West, Kendra L.; Gladden-Young, Adrianne; Oyejide, Nicholas E.; Matranga, Christian B.; Deme, Awa Bineta; James, Ayorinde; Tomkins-Tinch, Christopher; Onyewurunwa, Kenneth; Ladner, Jason T.; Palacios, Gustavo; Nosamiefan, Iguosadolo; Andersen, Kristian G.; Omilabu, Sunday; Park, Daniel J.; Yozwiak, Nathan L.; Nasidi, Abdusallam; Garry, Robert F.; Tomori, Oyewale; Sabeti, Pardis C.; Happi, Christian T.

In the limited Nigeria EVD outbreak, it was also possible to reconstruct a nearly complete transmission chain based on contact tracing alone ( Figure 2B ). Such a reconstruction is feasible in this case because (1) EBOV spreads primarily through direct contact, (2) there were few cases (multiple exposures were uncommon), and (3) intensive efforts were made to trace and monitor all suspected contacts. The contact tracing information resulted in a transmission tree similar to that suggested by genetic data, with the index case responsible for a majority of transmissions. This data also revealed that 1 individual (case patient 18) traveled from Lagos to Port Harcourt while infected with EBOV, where he acted as the index patient in a small secondary outbreak containing 4 additional EVD cases.