News media are extraordinarily effective in creating public panic, say researchers who analyzed Twitter feeds and Google searches following the limited outbreak of Ebola in the U.S. in October 2014.

The researchers wanted to understand the impact of news outlets and social media on people's behavior, especially as Ebola stories dominated U.S. media coverage for weeks, even though just five people were ultimately infected.

"Social-media data have been suggested as a way to track the spread of a disease in a population, but there is a problem that in an emerging outbreak people also use social media to express concern about the situation," says study leader Sherry Towers from Arizona State University  "It is hard to separate the two effects in a real outbreak situation."

The researchers from ASU, Oregon State University and Purdue University said the U.S. Ebola cases and the public response to news coverage of them provided a rare opportunity to study how news media can sow panic in a population.

The researchers collected and analyzed millions of Google searches and tweets during that October, looking for trending phrases on social media such as, "Do I Have Ebola?" and "Ebola symptoms."

"When we compared the temporal patterns in these data to the patterns in the number of Ebola-related news stories that ran on major news networks, we found that the peaks and valleys in both almost exactly matched," says researcher Carlos Castillo-Chavez of the ASU School of Human Evolution and Social Change. "We were amazed at how incredibly similar the temporal patterns were."

Changing trends in the news coverage could explain nearly all of the variations in social media searches and tweet subjects, the researchers found.

Public concern was especially incited by news videos, the study showed, with each broadcast news clip generating tens of thousands of Internet searches and tweets related to Ebola.

The researchers also noted that their study uncovered what they termed a "boredom" effect, showing that, as weeks passed, news stories related to Ebola became less likely to inspire people to conduct Ebola-related Google searches or sent tweets.

The study suggests tracking social media could be useful in future outbreak situations to provide significant insight into just how strongly news media may be manipulating public attitudes and responses, Towers says.

The study, "Mass Media and the Contagion of Fear: The Case of Ebola in America," was published in the PLOS One.