Hidden transmission

Winter 2017

More than a year after the Ebola epidemic in West Africa ended, researchers have identified 14 people who tested positive for the virus but had not been identified previously as having the infection. Twelve of them said they were asymptomatic; the other two recalled having a fever.

“The study corroborates previous evidence that Ebola is like most other viruses in that it causes a spectrum of manifestations, including minimally symptomatic infection,” says lead author Gene Richardson, MD, a former fellow in Stanford’s Division of Infectious Diseases and Geographic Medicine who is now a PhD candidate in anthropology at the university. “This shows there was a lot more human-to-human transmission than we thought.”

It is unclear whether asymptomatic individuals can transmit the virus.

In the Sierra Leone village where they conducted the study — an Ebola “hot spot” — researchers calculated the prevalence of minimally symptomatic infection at 25 percent. They say the results demonstrate the need for better public health efforts to contain the virus.

The study was published in November 2016 in PLOS Neglected Tropical Diseases.