A mystery illness has claimed at least 18 lives over the past few days in Nigeria, killing victims within a mere 24 hours of infection, the BBC reports. Health officials are scrambling to identify the illness—which is not Ebola or any other known virus—but have concluded that it's not contagious. Symptoms include headaches, blurred vision, and loss of consciousness. One theory is that it's ethanol poisoning from drinking home-made booze, the Premium Times of Nigeria reports. The victims, who are "commercial motorcyclists," fell ill after stopping at "local joints to take [an] alcoholic substance," says a health official. The drink was "mixed with roots and some other local herbs on the eve of the outbreak of the disease," he adds. Officials now plan to test that theory by giving toxicology tests to the five surviving victims. (More Nigeria stories.)