Last fall as the Ebola epidemic continued unabated, experts started discussing something that had never before been bandied about: the idea of Ebola becoming endemic in parts of West Africa. Endemic diseases, like malaria and Lassa fever in that region of Africa, are constant presences. Instead of surfacing periodically, as it always has before now, Ebola in an endemic form would persist in the human population, at low levels of transmission, indefinitely. The debate was stoked by a paper written by the World Health Organization (WHO) Ebola Response Team and published in October in the New England Journal of Medicine. The sentence that grabbed the world’s attention was saved till near the very end: “For the medium term, at least, we must therefore face the possibility that EVD [Ebola virus] will become endemic among the human population of West Africa, a prospect that has never previously been contemplated.” What would it mean exactly for Ebola to become endemic, and how would it change things? Still Fighting Christopher Dye, an author of the WHO paper, told Scientific American that, “To say it is endemic is, in one sense, to admit failure… Our goal, and our expectation, is that we will eliminate infection from the human population.” Agencies in the U.S. agree. “CDC doesn’t believe that Ebola has reached a point of being endemic in West Africa,” said Dr. Jordan Tappero, Director of the Centers for Disease Control and Prevention (CDC) Division of Global Health Protection. The CDC does not officially designate diseases as endemic; in the U.S. that is typically done by state agencies. On the international level the classification is made by the WHO, which has not yet classified Ebola as endemic. “The effort remains to get to zero cases of Ebola, and there are many efforts in place to accomplish that goal,” Tappero said. “We trust that sustained international support will result in an Ebola-free West Africa.” But the truth is that with the current epidemic now having lasted over a year, the line is blurring between an ongoing outbreak and the “new normal.” A Global Scourge? The implications of an endemic Ebola are equally muddled. Epidemic risk management consultants Jody Lanard and Peter Sandman wrote on their website about one worst-case scenario: that visitors to the region will always be at risk of Ebola, which could result in “sparks” unpredictably landing in other countries and causing catastrophic economic and public health effects. However other serious diseases, some of them more contagious than Ebola, have long been endemic in various developing countries. For example tuberculosis is endemic in major trade and tourism destinations including India, China and Brazil. But so far large-scale transmission to the U.S. has been avoided, even after drug-resistant cases of tuberculosis surfaced. And Ebola’s high mortality rates of 60 to 90 percent could actually prevent it from becoming endemic. (Mortality in the current epidemic has been pegged at about 70 percent.) Ebola’s victims are likely to die quickly rather than spreading the virus for years, as happens with HIV, hepatitis C and other endemic infections. Microbiologist Peter Piot, who co-discovered Ebola in then-Zaire in 1976, agrees. As he told the L.A. Times: “We (humans) are a very bad host from the virus’ point of view… A host that’s killed by a virus in a week or so is absolutely useless. So in all other outbreaks it eventually just disappeared from the human host and retreated into animals.” And once Ebola goes to ground in the West African animal population, it will make forays into local humans whenever they become hungry enough to eat some nice bushmeat. The virus may regret its foolish impulse to infect yet another dead-end host, but hey, what choice did it have?
Posted on: Wed, 21 Jan 2015 06:25:54 +0000
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