Mothers wait for their children to receive vaccinations last month at Redemption Hospital, formerly an Ebola holding center in Monrovia, Liberia. (John Moore/Getty Images)

As the unprecedented Ebola outbreak slowly fades in West Africa, it has left plenty of other public health worries in its wake.

One of the biggest threats: measles.

The massive disruptions Ebola caused to the health-care systems in Liberia, Guinea and Sierra Leone led to a significant drop in the number of children getting vaccinated for a range of diseases, including whooping cough and polio. In a study published Thursday in the journal Science, a group of researchers has calculated the potential fallout in the region if there was a measles outbreak. The measles virus is highly contagious and has surfaced in the wake of other humanitarian crises.

"It's so transmissible, and it's one of the first diseases you often see when there are crises leading to reductions in the vaccination rates," Justin Lessler, an assistant epidemiology professor at the Johns Hopkins Bloomberg School of Public Health and the study's lead author, said in an interview.

Lessler and his colleagues used data-backed mathematical models to simulate how quickly a measles outbreak could spread through vulnerable West African populations. Before the Ebola epidemic, they estimated, the region had about 778,000 children between 9 months and 5 years old who had not received a measles vaccine. Eighteen months after the Ebola outbreak began, there could be more than 1.1 million unvaccinated children — an increase of 45 percent.

The researchers found that a large measles outbreak could affect 100,000 more people in West Africa than it might have before the Ebola outbreak, or more than 200,000 overall, with most of the victims being young children. They estimated that such a catastrophe could cause 2,000 to 16,000 deaths. By contrast, the Ebola outbreak, which triggered a slow but massive global response last year, officially has led to 24,247 confirmed or suspected cases and 9,961 deaths, according to the latest figures from the World Health Organization.

Lessler acknowledged that the measles estimates in the Science study amount to an educated guess. As with Ebola, it's nearly impossible to predict whether a measles outbreak will happen, whether it would originate in crowded cities or rural countrysides, and how long it might last. In addition, he said researchers initially assumed in their models that 75 percent fewer children in West Africa were receiving vaccines as a result of the Ebola epidemic. That figure was in line with the best information available at the time, he said, but that "new information indicates that was probably a touch pessimistic."

Source: Johns Hopkins Bloomberg School of Public Health

The actual drop in vaccination rates appears to be between 25 and 50 percent, Lessler said. But even that less ominous scenario "still translates to tens of thousands of additional cases," he said.

The threat isn't merely hypothetical.

Lessler noted that a measles outbreak from 2010 to 2013  in the Democratic Republic of Congo — a country long plagued by political instability and civil unrest — led to nearly 300,000 cases and more than 5,000 deaths, many of them children under 5. Measles accounted for scores of childhood deaths during a famine in Ethiopia in 2000. 

Mit Philips, a health policy analyst for the international aid group Doctors Without Borders, said Liberia has reported 180 suspected measles cases this year, and it's likely that here are cases that haven't been reported because of overburdened or nonexistent disease surveillance systems in the region.

"We don't have a full assessment of the situation," Philips, who recently returned from West Africa, said in an interview from Belgium. "But here's an indication that there's something going on."

Beyond the obvious suffering Ebola has inflicted on the region, the epidemic also created a less obvious but no less tragic crisis. The outbreak destroyed the already fragile health-care systems in West Africa, shutting down hospitals and clinics and leaving entire populations without access to routine medical care.

The result was people dying of otherwise treatable or preventable conditions such as pneumonia, malaria, diabetes and strokes. Victims of heart attacks or those injured in car or bike accidents often had nowhere to turn. "If you broke a leg and you needed surgery, sorry," Sister Barbara Brillant, national coordinator of the Liberian Catholic Church's health council, told a Post reporter in September. "If you had appendicitis and needed surgery, sorry. It's not available."

Pregnant women have been particularly vulnerable. Even as more hospitals and clinics have reopened, Philips said she witnessed cases of women not being admitted unless they first tested negative for Ebola. Health workers, traumatized by the risk of infection and the deaths of their colleagues, remain reluctant to participate in procedures involving a lot of blood, such as C-sections and other surgeries.

"It's a huge challenge," Philips said.

Doctors Without Borders and other aid groups, along with ministries of health in each country and outside agencies such as the WHO and the Centers for Disease Control and Prevention, have been working to help reopen medical facilities and supply them with protective gear, basic medications and trained staff.

Officials also are meeting to discuss the feasibility of national vaccination campaigns, something the authors of Thursday's Science paper say is needed as soon as possible to combat a potential measles outbreak. Philips said worries remain about the lack of reliable surveillance efforts for a range of other diseases, including meningitis, cholera, yellow fever and Lassa fever. While cases of those disease likely exist in the region, she said, officials worry they might not be able to spot an outbreak quickly.

Lessler, the Hopkins researcher, agreed that Ebola left behind a long list of public health problems. But he said finding a way to vaccinate as many West African children as possible against measles could help prevent one major risk.

"Measles is not the only health threat that's been made worse by the Ebola crisis. It may not even be the worst," he said. "But it's certainly one we can do something about."