Tweets about Ebola appearing in Nigeria dramatically increased in the days leading up to the official announcement of an outbreak of the deadly disease there, according to a new study.
The study published in the American Journal of Infection Control suggests that a social media platform such as Twitter "can support and contribute to early warning systems in outbreak surveillance"—and potentially help stop the spread of a disease—even in less-developed countries of the world.
"Although Twitter adoption and use in resource-limited settings are lagging, there was an increase in the frequency of [Ebola]-related tweets in the days leading up to the official news alert," the authors of the study wrote.
The Ebola outbreak, which is still ongoing in Guinea and Sierra Leone, is the worst epidemic in the disease's recorded history. The United Nations on Wednesday noted that as of May 31, there have been 27,181 Ebola cases, most of them in West Africa, with 11,162 deaths.
One of those deaths, of Liberian national Thomas Eric Duncan, happened in Dallas, last October, after Duncan traveled there to visit family. Two nurses who cared for Duncan contracted Ebola, but recovered, as did several other Americans who had developed the disease in the U.S. after becoming exposed to the virus while in West Africa.
On July 24, 2014, two days before official word that Nigeria had joined several other African countries in having an Ebola case, there were 101 Twitter messages about a case in Nigeria—and those tweets reached nearly 1.2 million people, according to the study by Michelle Odlum and Sunmoo Yoon, researchers at the Columbia University School of Nursing.
The tweets included messages such as "#EbolaVirus 1st case discovered Lagos, pls spread the word," and "Guys, #EbolaVirus in Lagos. Be informed. Be careful." Another said, "Let us all be aware of this killer virus and advocate its prevents...HANDWASHING. That's one #Ebola."
Within two days, on July 26, there were 1,010 tweets related to an Ebola case in Nigeria, which reached more than 58 million people, according to the study.
"These tweets were not tweets from any health officials," said Odlum.
That day, Nigerian officials announced the probable case of Ebola involving Patrick Sawyer, a 40-year-old naturalized American who died on July 24. Sawyer had collapsed upon arrival after flying into Lagos from his native Liberia on July 20.
On July 30, more than 120.5 million were reached by tweets discussing news of Ebola in Nigeria, "a hundred times higher than the initial number," according to the study.
Nigeria ended up having 19 confirmed cases and nine deaths from the disease. The country was declared free of Ebola on Oct. 20.
It is not clear why people on Twitter were able to reveal the Ebola outbreak before it was announced publicly.
"I'm not really sure what actually went on," Odlum said.
She told CNBC that she and Yoon discovered the advance-warning tweets by accident, when they were asked to write a paper on infectious diseases and informatics, the use of information data in health care
Odlum said that she and Yoon, whose doctoral dissertation was on Twitter, decided to look at tweets as a method for "surveillance," or tracking such diseases.
"We had absolutely no idea" that they would find advance warning tweets about Eblola, Odlum said.
Yoon began downloading tweets written in English on July 24, which, coincidentally turned out to be the day that Sawyer had died in Nigeria.
Many of the tweets the researchers found ended up referring to sexually transmitted diseases.
But as a research assistant was sorting through the tweets, and "cleaning" them to get rid of messages that were not related to diseases, she "said 'why am I getting all of these Nigerian tweets?'" Odlum recalled.
When the researchers examined those tweets, and compared them to a timeline of Ebola news, they realized that messages about the virus had began spiking in the days before the official announcement of a case being found in Nigeria.
Odlum said she does not know if the tweets in advance of the announcement were merely a coincidence and reflected the fact that there were Ebola cases elsewhere in Africa at the time. But the first tweets on July 24 identified the city in Nigeria where the outbreak actually occurred, and that the tweets were "very personal" in showing concern for the people they hoped to reach with the news, she said.
And even if the tweets were spurred by actual advance knowledge of the case in Lagos, "it didn't keep the case from happening," she said.
But the widespread use of Twitter to discuss Ebola there in the week of the announcement "shows the power of social networks and the power of dissemination of information," she said.
The use of aggregated data online to track an outbreak isn't new. Google has a flu trends tool that monitors online searches for terms related to flu to track the spread of the virus.
Twitter's low cost, coupled with the increased use of social media in African countries, can be leveraged by governments and health agencies "to support either early detection or outbreak control," Odlum said.