In June 2015, NIAID and the Ministry of Health of Liberia launched the PREVAIL III study to evaluate people in Liberia who have survived Ebola virus disease (EVD) within the past two years. Investigators hope to better understand the long-term health consequences of Ebola virus infection, determine if survivors develop immunity that will protect them from future Ebola virus infection, and assess whether previously EVD-infected individuals can transmit the virus to close contacts and sexual partners. The five-year study is expected to enroll approximately 7,500 people, including 1,500 people of any age who survived EVD and 6,000 of their close contacts.
Preliminary findings from the study presented in February 2016 indicate that both Ebola survivors and their close contacts have a high burden of illness. However, the prevalence of eye, musculoskeletal, and neurological complications was greater among the individuals who survived EVD. Thirty-eight percent of the 97 male survivors who provided one or more semen samples for analysis had Ebola detected in their semen at least once. In one case, Ebola was detected in participant’s semen sample 18 months after he had EVD symptoms. In a subset of 126 contacts who reported sexual activity with a survivor, only four percent reported regular condom use, raising concerns about potential sexual transmission of EVD. However, no cases of sexual transmission have been detected in this study thus far.