The fatal Ebola outbreak in DR Congo is spreading rapidly, the WHO warned Friday, despite accelerating efforts to tackle the virus. The WHO said it was still racing to catch up with the worsening situation gripping northeastern DR Congo. "The outbreak remains serious" and is "evolving so fast", said Marie-Roseline Belizaire, the WHO Africa emergencies chief. "However, I have seen a response that is growing stronger every day," she told reporters in Geneva, speaking from Bunia, the capital of DR Congo's Ituri province, the outbreak's epicentre. The outbreak was declared on May 15, though transmission had been going undetected for some time beforehand. It is caused by the rare Bundibugyo strain of the virus, for which there is no vaccine or specific treatment. Read moreNo vaccine for new highly lethal Ebola outbreak, DR Congo warns, as death toll hits 80 There have been 896 confirmed cases so far in DR Congo, including 232 confirmed deaths, with 21 new cases in the last 24 hours, according to the latest WHO update. More than 90 percent of known cases in DR Congo have been in conflict-wracked Ituri. The outbreak has also spread to North Kivu and South Kivu provinces. Belizaire said the epidemic was evolving so quickly that the response was racing to keep pace with the virus, which spreads by close contact and infected bodily fluids.