Scientists are using blood samples collected throughout the Ebola outbreak for tracking the spread of the virus from one country to another by tracking small mutations in its gene sequences. Promising progress has been made so far but the picture is not yet complete.
Virus mutations detected in Sierra Leone last spring were found in Mali and Liberia later. Scientists are trying to find out whether this resulted from movement of people across borders.
Scientists are searching for viral mutations owing to their potential influence on effectiveness of treatment or diagnoses. Ebola diagnostic tests experimental treatments have been changed on the basis of information about how the virus evolved from the previous outbreaks to the one in West Africa.
Genetic mutations is also being used for understanding the overall course of the epidemic. Daniel J. Park, group leader of viral computational genomics at the Broad Institute of MIT and Harvard said "They let us trace history."
Jeffrey R. Kugelman, the chief of the bioinformatics branch of the Center for Genomic Sciences at the Army Medical Research Institute of Infectious Diseases said "We can tell you with a high likelihood that this sequence is derived from this other sequence."
He also informed that the interviews of the epidemiologists rely heavily on the "quality of your conversations with people, and whether they're telling the truth and whether they understood the situation properly."
Making sense of scientific evidence from sequencing depends on efficient records about where and when the samples were taken. According to Edward C. Holmes, a fellow at University of Sydney in Australia, both the strategies are required to tell a complete story.
During the first year of the West Africa outbreak, sequences of viruses from only about 250 patients were made publicly available.
The researchers have assigned sequences to three clusters along with original versions of virus discovered in Guinea last year. Three clusters are somewhat mutated descendants of the Guinean virus. Two to three months later, they were found circulating in Sierra Leone.
Viral descendants of cluster two have been found in samples of all the Liberian Ebola patients whose viruses have been sequenced and have been made public. It was also found in patients in Mali who have traveled from and lived in Guinea.