Ebola Eludes Drug Testing Once More as Outbreak Tapers Off

As the Ebola outbreak ebbs in central Africa, the lethal virus has once again evaded testing that’s crucial to developing a cure.

The last suspected case in a contagion that began in May in the Democratic Republic of Congo tested negative on June 12, the World Health Organization said by email this week. If no new patient emerges by July 25, the outbreak will be officially over. The WHO estimates that 24 people survived the infection and 29 died. By contrast, more than 11,000 died in the West African epidemic that ended in 2016.

By the time experimental medicines developed ...