By Bahar Gholipour
The reasons why the Ebola outbreak in West Africa has grown so large, and why it is happening now, may have to do with the travel patterns of bats across Africa and recent weather patterns in the region, as well as other factors, according to a researcher who worked in the region.
The outbreak began with Ebola cases that surfaced in Guinea, and subsequently spread to the neighboring countries of Liberia and Sierra Leone. Until now, none of these three West African countries had ever experienced an Ebola outbreak, let alone cases involving a type of Ebola virus that had been found only in faraway Central Africa.
But despite the image of Ebola as a virus that mysteriously and randomly emerges from the forest, the sites of the cases are far from random, said Daniel Bausch, a tropical medicine researcher at Tulane University who just returned from Guinea and Sierra Leone, where he had worked as part of the outbreak response team.
“A very dangerous virus got into a place in the world that is the least prepared to deal with it,” Bausch told Live Science.
In a new article published today (July 31) in the journal PLOS Neglected Tropical Diseases, Bausch and a colleague reviewed the factors that potentially turned the current outbreak into the largest and deadliest Ebola outbreak in history. Although the focus is now on getting the outbreak under control, for long-term prevention, underlying factors need to be addressed, they said.
Here are five potential reasons why this outbreak is so severe:
The virus causing this outbreak is the deadliest type of Ebola virus.
The Ebola virus has five species, and each species has caused outbreaks in different regions. Experts were surprised to see that instead of the Taï Forest Ebola virus, which is found near Guinea, it was the Zaire Ebola virus that is the culprit in the current outbreak. This virus was previously found only in three countries in Central Africa: the Democratic Republic of the Congo, the Republic of the Congo and Gabon.
Zaire Ebola virus is the deadliest type of Ebola virus — in previous outbreaks it has killed up to 90 percent of those it infected.
But how did the Zaire Ebola virus get to Guinea? Few people travel between those two regions, and Guéckédou, the remote epicenter of first cases of disease, is far off the beaten path, Bausch said. “If Ebola virus was introduced into Guinea from afar, the more likely traveler was a bat,” he said.
It is also possible that the virus was actually in West Africa before the current outbreak, circulating in bats — and perhaps even infected people but so sporadically that it was never recognized, Bausch said. Some preliminary analysis of blood samples collected from patients with other diseases before the outbreak suggests people in this region were exposed to Ebola previously, but more research is needed to know for sure.