When several people died suddenly late last month in Liberia after attending a funeral in the southern county of Sinoe, alarm bells sounded: Had Ebola returned to West Africa? In 2014 and 2015, the largest known outbreak of the deadly disease killed more than 11,000 people in Liberia and two neighboring countries. But instead of signaling the return of that virus, the outbreak—which so far has sickened 30 people and killed 13—may have highlighted its legacy: a disease-monitoring system put in place after Ebola. Although the public health response was far from flawless, it rapidly stilled Ebola fears and now points to a different disease: meningitis.
On Monday, just 13 days after the first cases were reported, the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta announced that samples from four patients tested positive for Neisseria meningitidis serotype C, a bacterium that infects the membranes surrounding the brain and, if untreated, can kill up to half the people it sickens. The disease spreads through close contact such as kissing and often causes devastating epidemics across what is known as the meningitis belt stretching across Africa. But it is unfamiliar in Liberia.
The first patient, an 11-year-old girl, arrived at the F. J. Grant Memorial Hospital in Greenville, a regional capital, on 23 April, suffering from vomiting and diarrhea but also mental confusion and hallucinations. Within an hour she was dead. Another patient with similar symptoms came the next day. Then, on the morning of 25 April, 14 patients arrived. At that point, the “integrated disease surveillance and response,” a framework established post-Ebola, kicked in. At least one health worker in every district has been trained to monitor and report any suspicious events, says Alex Gasasira, the World Health Organization representative in Monrovia. They then inform county officials, who pass the information up to the national level.
“Turn-around time for transportation and results have dropped drastically,” says Thomas Nagbe, director of the epidemiology and infectious diseases division at the National Public Health Institute of Liberia. The alert reached Monrovia in a matter of hours. That same day, an investigative team, which included scientists from CDC stationed in Monrovia, drove to Greenville, an 8-hour car ride in the current rainy conditions. At the same time a motorcycle courier carrying patient samples set out from the hospital, arriving in Monrovia at about 7 p.m. that evening, Gasasira says. Later that night the National Reference Laboratory ruled out Ebola, to widespread relief.
Tests also ruled out Lassa fever, and the main hypothesis became poisoning, because all the patients had attended the same funeral on 22 April, except for a woman who died in Monrovia. Her husband, who also died, did attend, and investigators speculated that he may have brought home food or taken food from his home to the funeral. Those investigations continue. CDC is also testing urine, blood, and serum samples for metals and some environmental poisons, according to a spokesperson. “We are not ruling out anything yet,” Gasasira says.
But the evidence for meningitis is mounting. A Kenyan pathologist who did autopsies this weekend on two of the bodies noted signs consistent with meningitis, Nagbe says. Although few patients had fever, a common sign of meningitis, other symptoms and the short time between onset of disease and death are typical. “The clinical presentation was very unusual, that is why meningitis was not at the top of our list,” Gasasira says. Samples from the other patients will be tested for N. meningitidis as well, Gasasira says. “Then we’ll be much more confident.”
A big question is why N. meningitidis should suddenly appear in Liberia. Since a new vaccine was introduced in 2010, the number of meningitis cases in Africa has dropped dramatically. But that vaccine protects only against serotype A. The number of infections with serotype C has gone up; Nigeria and Niger are now battling a large outbreak. “Meningitis C is filling the vacuum created where meningitis A was a problem,” Gasasira says. “But we never had Type A.” Another possibility is that the disease was present in Liberia but just wasn’t picked up in the past.
Some of the precautionary measures that have already been taken could help limit any further spread. For instance, patients were given prophylactic antibiotics, and lists of people who had contact with cases were quickly drawn up. The response suggests that Liberia’s capacity for detecting a disease outbreak has greatly improved in the wake of Ebola, says Vincent Munster, a virologist at the National Institute of Allergy and Infectious Diseases’ Rocky Mountain Laboratories in Hamilton, Montana. But West Africa, with all the international resources poured into it, is a special case, he adds. “There are number of countries that are nowhere near that situation.”