The Ebola epidemic in West Africa could cause more than 1 million casualties unless improved isolation and treatment of patients are put in place, new projections of the outbreak suggest. Without drastic improvements, weekly cases of Ebola should increase from hundreds to thousands, World Health Organization officials and others report in the New England Journal of Medicine September 23. In less than six weeks, the scientists say, the number of infections could surpass 20,000.
The report’s authors also calculate that the fatality rate of this year’s infections is about 71 percent, substantially higher than earlier estimates of around 50 percent.
Worrisome projections also come from the Centers for Disease Control and Prevention. Experts there now predict that within a week, the reported outbreak numbers could top 8,000 cases. But owing to underreporting, the actual infection numbers might be 2.5 times as high as that, a team from CDC says. If that is true, the 20,000-case mark might be reached by September 30, a month earlier than the WHO team projected in earlier estimates.And, if the epidemic continues unabated, the reported number of Ebola cases in Liberia and Sierra Leone could reach 550,000 within four months, the CDC team warns. That would translate to an estimated 1.4 million cases when underreporting is taken into account, the scientists say September 23 in Morbidity and Mortality Weekly Report.
The WHO report also suggested the chilling possibility that Ebola in this region might escape full eradication. Endemic Ebola raises long-term public health and economic issues, says Tara Smith, a microbiologist and epidemiologist at Kent State University in Ohio. “That would be a destabilizing force for these countries. They have already lost industry and tourism.” But she commends CDC and WHO for “trying to come to grips with this” by spelling out the potential downsides. If the transmission rates remain high, getting the epidemic under control will only get harder.
Ebola spreads when a healthy person becomes exposed to infected fluids such as urine, blood or saliva from a sick patient. If the ill person lives in a city and can’t get to a hospital, the chance that he or she will infect someone else is high. There are more sick people than hospital beds in which to put them in West Africa, WHO reports.
As of September 23, the death toll was 2,811, making this Ebola outbreak deadlier than all earlier ones combined. Health officials are losing the “numbers game” against the virus, the WHO team notes. If each sick person infected no more than one person, the size of the epidemic would remain stable or start to fall. But instead, each sick person on average has been infecting more than one person, and the epidemic continues to grow, the WHO panel finds.
If the transmission rates remain high, getting the epidemic under control will only get harder. “You can’t do contact tracing if you have 30,000 people infected,” Smith says.
The WHO and CDC scenarios assume that no changes in disease control will take place. As public health officials in Liberia, Sierra Leone and Guinea fail to contain transmission of the lethal virus — and as wide use of experimental vaccines and drugs for Ebola still appears months away — the outlook has become more pessimistic. CDC estimates that getting 70 percent of infected people into Ebola treatment units could stem transmission and halt the epidemic. But the three countries hit hardest have not been able to effectively quarantine the sick. So the number of Ebola cases is doubling every 15 to 20 days in Liberia and every 30 to 40 days in Guinea and Sierra Leone, CDC researchers say.
Yet control is still possible, health care officials say. Key to stemming the outbreak will be isolating the sick from the healthy, and soon.
“A lot of it is getting the political will. As it is, things have to come to the attention of the world before changes get made,” Smith says. The better approach is proactive, she says, “spending the money before you get to this horrific tipping point.”