Recrudescence of Ebola virus disease outbreak in West Africa, 2014–2016

Lee, Hyojung; Nishiura, Hiroshi

OBJECTIVES: There have been errors in determining the end of the Ebola virus disease (EVD) epidemic when adhering to the criteria of the World Health Organization. The present study aimed to review and learn from all known recrudescence events in West Africa occurring in 2014–2016. METHODS: Background mechanisms of five erroneous declarations in Guinea, Liberia, and Sierra Leone during 2014–2016 were reviewed. RESULTS: Three cases of recrudescence were suspected to have been caused by sexual contact with survivors, one to be due to international migration, and one was linked to a potentially immunocompromised mother. The three sexual transmission events involving survivors—the first two in Liberia and one in Sierra Leone—required 164 days, >150 days, and approximately 180 days, respectively, from discharge of the survivors to confirmation of the recrudescent case. CONCLUSIONS: The events of recrudescence were associated with relatively uncommon routes of transmission other than close contact during burial or care-giving, including sexual transmission, possible immunocompromise, and migration. Recognition of the sexual transmission risk among survivors could potentially involve discrimination, which may lead to under-ascertainment.