Despite Headlines, Ebola Doesn't Yet Register Strongly in the Scientific Literature

Fabrizso Bensch/Reuters

The crisis of Ebola virus disease (EVD) in West Africa, at this writing, continues to deepen, with the World Health Organization (WHO) now reporting more than 3,600 cases, and deaths exceeding 1,800. And yet, despite the headlines and the notes of alarm, Ebola as a research topic remains a comparatively limited presence in the scientific literature.

The Thomson Reuters Web resource ScienceWatch tracks trends and performance in research, based on the company's coverage, in the Web of Science, of more than 12,000 scientific journals and other scholarly sources.

In a recent article, ScienceWatch's medicine correspondent, David Sharp, examines foundational literature on Ebola since the initial outbreak in 1976. Some 2,000 papers explicitly mentioning "Ebola" in their title, abstract, or keywords have been indexed since the virus first emerged nearly four decades ago. As a point of comparison, roughly 4,000 papers indexed over the same period mention the tropical disease "dengue fever" (although, as a general benchmark, neither total approaches the nearly half-million articles since 1976 that feature permutations of "diabetes").

As Sharp notes, the topic of Ebola has thus far failed to attain the critical mass that characterizes more populous, active fields of research. One measure of this current shortfall involves citations -- those markers of the essential scholarly activity undertaken by scientists when they read and footnote each other's work. These citations, when studied in aggregate, demonstrate links between related research and establish distinct areas of specialized investigation. Thomson Reuters tracks these citation-based groupings with its Research Fronts. Each of these clusters, identified through automated analysis of citation patterns, forms itself into a "core" of papers that are frequently cited together by later papers, thus marking a discrete specialty area.

In the current edition Essential Science Indicators, a tool within Thomson Reuters' research analytics suite, InCites, only one Research Front is devoted to Ebola. And only three papers form the cluster's core of foundational research. Even Middle East respiratory syndrome (MERS), identified less than two years ago, has already accounted for its own Research Front, with a comparatively crowded core of 39 reports. Influenza, by contrast, including studies of the H1N1 outbreak in 2009, is the subject of 42 Research Fronts. (As with the numbers of published papers discussed above, prevalent diseases account for the greatest quantities of biomedical Research Fronts: roughly 80 expressly devoted to diabetes, and nearly 500 centering on cancer.)

A similar imbalance is evident when assessing the impact of individual papers. Essential Science Indicators tracks papers that register among the top 1 percent most cited for their given specialty and year of publication (in other words, the papers most frequently read and footnoted by other scientists). These papers are officially designated as "highly cited." Ebola research accounts for eight such papers over the last decade, while MERS (again, the notably more-recent phenomenon) has already occasioned 14 highly cited papers, with influenza underlying more than 370.

As Sharp observes, the comparatively small number of Ebola cases over the years registers below what would typically attract pharmaceutical companies to undertake conventional R&D efforts. Sharp also notes, however, that the current crisis is the largest outbreak to date and is still unfolding. Perhaps we are witnessing the last moment that Ebola will not register as a central, active topic of worldwide investigation.

To read the complete ScienceWatch story, please click here.