As Ebola kills some, it may be quietly immunizing others

As Ebola continues to spread in West Africa, it may be silently immunizing large numbers of people who never fall ill or infect others, yet become protected from future infection. If such immunity is confirmed, it would have significant ramifications on projections of how widespread the disease will be and could help determine strategies that health workers use to contain the disease, according to a letter published Tuesday in the Lancet medical journal.

Dr. Steve Bellan, a postdoctoral researcher, and Dr. Lauren Ancel Meyers, a professor, both in the Department of Integrative Biology at The University of Texas at Austin, were two of the authors on the letter, which calls on public health authorities to determine how commonplace it is for people to be infected by Ebola without ever developing symptoms or spreading the disease, and whether these individuals are then protected from future infection.

"Ultimately, knowing whether a large segment of the population in the afflicted regions are immune to Ebola could save lives," Bellan noted. "If we can reliably identify who they are, they could become people who help with disease-control tasks, and that would prevent exposing others who aren't immune. We might not have to wait until we have a vaccine to use immune individuals to reduce the spread of disease."

The letter notes that researchers have found evidence of asymptomatic Ebola infections in the aftermath of prior Ebola outbreaks, but it is not yet known whether such infection provides immunity. They conclude that resolving this question and identifying naturally immunized individuals could prove critical in public health efforts to contain the disease, as well as in accurately estimating the likely spread of the disease.

"Understanding the prevalence and immunological effects of these silent Ebola infections is critical to making reliable epidemic projections and improving control efforts," Professor Meyers said. "We believe that we can and should investigate this phenomenon as soon as possible."