Via The New York Times, a report by Sheri Fink: Tracing the Ebola Outbreak, Scientists Hunt a Silent Epidemic.
Scientists are using blood samples collected throughout the Ebola outbreak to map the virus’s spread from country to country by tracking tiny mutations in its gene sequences.
The picture is not yet complete, but intriguing discoveries have been made. Virus mutations first detected in Sierra Leone last spring were found later in Liberia and Mali, and scientists are examining whether this resulted from the chance movements of people across borders.
While some scientists think it is unlikely that the mutations made a difference in how the virus functioned, others are looking at whether this version of the virus had properties that made it more capable of causing infection.
Scientists look for viral mutations because of their potential influence on the effectiveness of diagnostics or treatments. Researchers have changed Ebola diagnostic tests and experimental treatments based on information about how the virus has evolved from previous outbreaks to the one in West Africa.
Genetic mutations are also beginning to serve as a tool to understand the overall course of the epidemic, which could offer insights into how to improve the response to outbreaks. “They let us trace history,” said Daniel J. Park, group leader of viral computational genomics at the Broad Institute of M.I.T. and Harvard.
Tracking changes in the virus’s genetic sequence is an objective endeavor, unlike interviewing people on the ground. “We can tell you with a high likelihood that this sequence is derived from this other sequence,” said Jeffrey R. Kugelman, the chief of the bioinformatics branch of the Center for Genomic Sciences at the Army Medical Research Institute of Infectious Diseases.
But epidemiologists’ interviews rely heavily “on the quality of your conversations with people, and whether they’re telling the truth and whether they understood the situation properly,” he said.