OHANNESBURG (AP) — The global health community gulped Thursday with the announcement that a case of Ebola had been confirmed in a city of more than 1 million in Congo, bringing the latest outbreak of the often deadly hemorrhagic fever out of remote rural areas. "Confirmation of urban #Ebola in #DRC is a game changer in this outbreak - the challenge just got much much tougher," the World Health Organization's emergencies chief, Dr. Peter Salama, said on Twitter. Here's a look at the outbreak. ___ WHAT IS EBOLA? Ebola is a virus that without preventive measures can spread quickly between people and is fatal in up to 90 percent of cases.